Évolutions du document - Portail des Opérations de Recherche

Transcription

Projet ALZIRA
Alerte Locale et personnalisée en Zone à
Importants Risques d’Accidents
Etude sur les alertes et
la prévention des accidents
Analyse bibliographique sur Internet
ALZIRA Etude sur les alertes et la prévention des accidents – 12-2002
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SODIT
Évolutions du document
Date
12/12/01
Indic
Auteur
e
1.0 Yves DELANNE Création
LCPC Nantes
Objet
Pages / §
Toutes
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SOMMAIRE
1 - PRESENTATION DE L’ETUDE CONDUITE ............................................................................. 4
1 - PRESENTATION DE L’ETUDE CONDUITE ............................................................................. 4
2 - METHODE DE TRAVAIL .............................................................................................................. 5
3 - LES THEMES.................................................................................................................................. 5
3.1 - PREVENTION DES SORTIES DE ROUTES ................................................................................... 5
3.1.1- Données des documents ................................................................................................. 5
3.1.2- Données du WEB sur la prévention des sorties de route ........................................... 6
a - Action sur l’infrastructure .............................................................................................. 6
b - Panneaux à messages variables .................................................................................. 6
c - Guidage sur ligne de rive (lane trackers) ................................................................... 6
d - Signaux d’alerte ................................................................................................................ 6
3.2 - PREVENTION DES COLLISIONS EN CROISEMENT ...................................................................... 7
3.3 – CONCLUSIONS .......................................................................................................................... 7
EXTRAITS DES DOSSIERS DU WEB............................................................................................. 8
EU PROJECTS ..................................................................................................................................... 9
Work-package 1 of the EU project GADGET ........................................................................... 9
Car dynamics safety devices .................................................................................................. 9
Alcohol control systems (ACS). .............................................................................................. 9
Driver alertness monitoring (DAMS) ...................................................................................... 9
Work-package 2 of the EU project GADGET ........................................................................... 9
Advisory speed limit ................................................................................................................. 9
SHOULDER RUMBLE ......................................................................................................................... 10
Rumble strip effectiveness, drift-off-road accident reductions............................................. 10
VARIABLE MESSAGE SIGNING ........................................................................................................... 10
Effects of weather-controlled variable message signing on driver behaviour ................... 10
An Evaluation of Dynamic Curve Warning Systems in the Sacramento River Canyon:
Final Report ................................................................................................................................. 12
AVOIDANCE DEVICES TEST AND ACCEPTANCE ................................................................................ 15
DOT To Test System Designed To Prevent Run-off-the-Road Crashes ........................... 15
Customer acceptance of crash avoidance devices ............................................................... 15
GUIDING SYSTEMS ............................................................................................................................ 16
The new" road angel gps system from blackspot .................................................................. 16
Lane Tracking System: "Road Scout" ..................................................................................... 16
LANE TRACKING ................................................................................................................................ 16
AURORA...................................................................................................................................... 16
Run-Off-Road Collision Countermeasures program ............................................................. 16
Lane Drift Warning System (LDWS)....................................................................................... 17
SAVETRAC ......................................................................................................................................... 17
INTELLIGENT STABILITY AND HANDLING SYSTEMS ......................................................................... 18
INTELLIGENT VEHICLE INITIATIVE (NHTSA).................................................................................... 18
Reducing Motor Vehicle Crashes with the DOT's Intelligent Vehicle Initiative (NHTSA) 18
DETECT DROWSY DRIVERS ............................................................................................................. 21
SIEMENS SYSTEM ........................................................................................................................ 21
INFRASTRUCTURE INTERSECTION COLLISION AVOIDANCE ............................................................ 21
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1 - Présentation de l’étude conduite
L’étude PREDIT 2 ALZIRA qui s’achève a montré qu’un conducteur abordant un virage
réputé accidentogène peut être prévenu par une alerte personnalisée dans son véhicule du
danger qu’il encourt si son comportement n’est pas en accord avec la topologie du site et les
conditions météorologiques locales du moment.
L’annexe technique (page 3) donne une définition plus large du concept d’alerte et cite les
applications suivantes :
-
Virage : Le conducteur aborde un virage dangereux avec peu de visibilité : à l’entrée de
la zone une balise lui transmet la vitesse limite admise dans ce virage. Si la vitesse
courante du conducteur à ce moment là est excessive, le système de bord lui transmet
une alerte pour lui faire prendre conscience du danger et lui faire réduire sa vitesse.
-
Verglas : Le conducteur pénètre dans une zone réputée dangereuse pour ses risques de
verglas l’hiver. A l’entrée de la zone, la balise lui transmet la température de la route et la
vitesse limite admise associée. Le conducteur est alors éventuellement alerté sur la
présence de verglas.
-
Tunnel : A l’entrée d’un tunnel, une balise informe les conducteurs sur les incidents à
l’intérieur du tunnel, sur une distance inter-véhicule non respectée, une vitesse
excessive, etc. Les incidents peuvent notamment être détectés automatiquement par un
traitement de l'information issue des balises (rupture dans le débit des véhicules).
Egalement, dans ce cas, l’allumage et l’extinction des phares peuvent êtres pilotés
automatiquement.
-
ACC navigation : Si le véhicule est équipé de systèmes électroniques d’aide à la
conduite type ACC, systèmes de navigation, systèmes de suivi de trajectoires, la balise
peut également transmettre des informations utiles sur la topologie particulière de la
route en amont (virage important, côte, interdiction de voie et déviation associée, etc.).
-
Passage à niveau : un véhicule arrive à un passage à niveau le conducteur est averti
qu’il croise une ligne de chemin de fer le message peut être renforcé si l’on a
connaissance d’un train à l’approche.
Ce rapport correspond au lot 7 de l’annexe technique
Il s’agit d’effectuer :
- une étude sur les travaux en cours ou récemment réalisés abordant la question des
alertes « circonstanciées » sur la base d’investigations INTERNET et de contacts
directs avec certains organismes européens et nord américains.
- une étude sur les possibilités de généraliser ce concept d’alerte ciblée à d'autres sites
Une analyse des statistiques d’accidents extraites de la détermination des sites a priori
accidentogènes permettra de lister un certain nombre de points noirs sur lesquels le concept
ALZIRA pourra être transposé.
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2 - Méthode de travail
La recherche a été conduite :
- par la lecture d’une série de documents collectés dans des études antérieures de
sécurité.
- par des interrogations INTERNET en ciblant de façon progressivement
« convergente » les domaines abordés (moteur GOOGLE et utilisation de
COPERNIC PRO)
- par contact par courrier électronique avec certains auteurs d’études
Pour la recherche INTERNET un dossier annexé a été établi à partir des fichiers
téléchargés. Ce dossier a été structuré par thème et par sujet.
3 - Les thèmes
3.1 - Prévention des sorties de routes
3.1.1- Données des documents
Ce type d’accident représente une part importante des accidents (de l’ordre de 40%) .
Ce sujet a fait l’objet d’un rapport récent du Laboratoire d’Accidentologie et de Biomécanique
commun à RENAULT et PSA PEUGEOT CITROËN :
« Les sorties de voie involontaires »
par François Bar et Yves Page - mai 2002
Sur la base d’études détaillées d’accident et d’une identification par scénarios types les
auteurs proposent trois grands types de mesures :
1.
des mesures qui alertent le conducteur sur son état ou sur l’état de l’environnement
2.
des mesures correctives qui rectifient le déport ou la perte de contrôle (détection de
l’angle de déport par rapport à une trajectoire de référence)
3.
des mesures de récupération qui pourraient se substituer aux actions confuses et/ou
trop amplifiées des conducteurs sur le volant et la pédale de frein
La première mesure concerne les alertes d’état d’hypovigilance et/ou l’inadéquation
dynamique probable dans des zones à sollicitation plus importante. Seule ce dernier cas est
traité dans le concept ALZIRA alors que les défauts de guidage (conserver une trajectoire
« sure ») sont les cas le plus fréquents : 63% dans l’étude du LAB dont tous ceux qui se sont
produits en ligne droite et 50% des cas en courbe.
Un étude finlandaise du programme SAFESTAR du Transport RDT Programme of the 4iéme
framework programme EU :
« Head on and run-off-the road accidents on rural roads in Finland”
confirme que la mesure la plus efficace en réduction d’accident serait une alerte d’état du
conducteur (santé, vigilance, alcool , drogue,..). Selon ce rapport, cette mesure concerne
60% des pertes de contrôles (8% des cas sont considérés comme des suicides !…).
Les études américaines s’orientent plutôt vers une solution de guidage latéral (voir dossier
WEB)
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3.1.2- Données du WEB sur la prévention des sorties de route
Mots clés principaux : Drift-Off-Road, Run Off Road, Single Vehicle Accidents Prevention,
active safety systems for road-departure prevention, lane drift warning systems
a - Action sur l’infrastructure
Les différentes études lues confirment l’efficacité du traitement des bandes de rives.
Les marquages « sonores » en rive se sont avérés efficaces à condition toutefois qu’une
partie de la rive soit revêtue et permette le contrôle d’urgence de la trajectoire.
b - Panneaux à messages variables
Une étude finlandaise et une étude américaine récente concluent à l’efficacité de cette
mesure.
Sur la base de ces études il semble préférable d’afficher une vitesse limite avec
simultanément l’affichage de la vitesse pratiquée par le véhicule en approche de manière à
lui faire prendre conscience de la réduction de vitesse nécessaire. Cette dernière disposition
a été mise en œuvre avec succès en Californie (dossier WEB).
Pourtant, divers autres travaux sur le sujet indiquent la difficulté d’obtenir un changement
« circonstancié » sur la base de l’affichage d’une vitesse recommandée pour une situation
particulière.
La problématique « psychologique » de l’alerte est traitée dans un document WEB dont des
extraits ont été annexés à ce rapport. L’idée essentielle développée est qu’une alerte
parvient assez rarement à modifier une attitude.
Un certain doute demeure sur l’efficacité de ce mode d’alerte pour des routes fréquemment
utilisées par les usagers.
c - Guidage sur ligne de rive (lane trackers)
C’est la méthode qui, au sens de l’ « ITS » américain, semble la plus prometteuse.
Le programme “Intelligent Vehicle Initiative (IVI)” a abouti à différentes solutions dont les
tests sont en cours (2001-2003).
Le paragraphe « IVI » de l’annexe décrit les travaux conduits. Sur le sujet qui nous concerne
il est signalé qu’une communication intitulée :
« Analysis of Off-Roadway Crash Countermeasures for Intelligent Vehicle Applications”,
a été présentée at the Society of Automotive Engineers World Congress in Detroit, Michigan
en mai 2002. Cette article a été commandé.
Une interrogation du type “road lane tracking”donne un nombre très important de documents
américains confirmant les choix pris dans le programme IVI 1995-1997.
d - Signaux d’alerte
Drowsy driver detection:
Le système est compris dans son principe par les usagers mais la crainte est qu’il soit
perturbé par le port de lentilles ou de lunettes de soleil.
Ce sujet est particulièrement traité pour les véhicules lourds
Lane-drift warning system
Une caméra montée sur le miroir intérieur permet de suivre le marquage latéral par
ailleurs, des capteurs suivent les mouvements du véhicule et les actions du conducteur
avec ces données le risque de sortie de route est établi.
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Le système enclenche :
- une alarme sonore
- la mise en vibration du volant
- une commande d’assistance au conducteur pour redresser la trajectoire
Mitsubishi Motors Corporation
De nombreux systèmes de ce type sont décrits sur le net.
L’alerte donnée est souvent le « rumble strip sound » (AutoVue™ Lane Departure Warning
(LDW) system by Iteris, lane trackers by Williamson Associates, etc…)
3.2 - Prévention des collisions en croisement
Ce problème nécessite des systèmes qui alertent les conducteurs d’un risque potentiel de
collision. Il est donc nécessaire de définir la position des véhicules et leurs vitesses pour
pouvoir alerter en temps utile.
Plusieurs solutions sont proposées dans un dossier de l’US Department of Transportation.
L’utilisation de balise DSCR est une solution envisagée.
3.3 – Conclusions
Une recherche à l’adresse http://www.its.dot.gov/ivi/ivi.htm permet d’éditer toutes les études
en cours aux USA.
Pour les sorties de route (ou de voie) considérées comme une cause majeure d’accidents
mortels, la solution mise en œuvre dans l’étude ALZIRA n’est pas envisagée.
Par contre pour les croisements c’est une possibilité envisagée.
Les recherches INTERNET sur les tunnels n’ont pas donné d’informations utilisables pour
cette étude.
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Extraits des dossiers du WEB
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EU projects
Work-package 1 of the EU project GADGET
Telematics - Report (WP1):
Schulze, H., Christ, R., Heijer, T., Mäkinen, T., Nilsson, L. In Vehicle Safety devices. GADGET
Work-package report. BASt, Bergisch-Gladbach, 1999.
Car dynamics safety devices
Four types of systems belong to the category car dynamics: Anti-block systems (ABS),
Traction control systems (ASR), Electronic stability program (ESP) and Adhesion monitoring,
and Heading control systems (HCS).
Alcohol control systems (ACS).
Systems helping to prevent driving under influence of alcohol are called alcohol control
systems (ACS). When a breath alcohol ignition interlock device in the vehicle is installed,
prior to starting, the driver is required to provide a breath sample by blowing into the device.
If the alcohol content of the breath sample exceeds a pre-set limit, the starter will be locked
out and the vehicle cannot be driven. Once the vehicle is in motion, the driver is required to
provide additional breath samples at random intervals. In the USA, drivers who lost their
license because of driving drunk, get the license back if they agree to drive only with their car
fitted with an alcohol control unit. These units are recommended for novice drivers.
Driver alertness monitoring (DAMS)
Dealing with systems of Driver alertness monitoring (DAMS) you find two classes of
methods which are used to monitor the driver's state of drowsiness, methods which analyse
the stability of the driver’s steering actions (lane-related measures), and methods which use
physiological parameters to estimate the condition of the driver (physiological measures).
Whenever the performance, observed with one or both methods, falls below a certain
threshold, the driver is supposed to be drowsy and a series of countermeasures are
activated.
Work-package 2 of the EU project GADGET
Road environment - Report (WP2):
Sagberg, F., Hakkert, S., Larsen, L., Leden, L., Schmotzer, C., Wouters, P. Visual modification of
the road environment. Deliverable D2 from the EU project GADGET. Oslo: Institute of Transport
Economics, TØI, 1999.
Advisory speed limit
At special sites or under special conditions advisory speed limit signs are used. The main
advantage of the advisory character is that drivers are not enforced to lower speeds when
the actual situation does not fit the mandatory limit. This can be the case for seasonal or
temporary changes in weather conditions. The idea is that drivers tend to ignore regulatory
information in general, when discrepancies between situation and demanded behaviour
occur very often. Sometimes the combination of warning signs together with advisory speed
limits has been suggested. Additional advisory speed signs have not been shown to be more
effective in motivate drivers to reduce their speeds through curves than the curve warning
sign alone. New installations of speed limits at sites with an existing curve warning sign
should be given low priority. The implicit information of curve warning signs to reduce speed
seems to be sufficient. There exists no information about the principal functionality of
advisory speed limits. A problem could be that the ("weak") advisory information is neglected
completely because of the yet well established selective obedience of the ("strong")
mandatory speed limits.
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Shoulder Rumble
Rumble strip effectiveness, drift-off-road accident reductions
To help decrease the number of accidents caused by drowsy drivers, engineers for the
Pennsylvania Turnpike developed and installed an innovative type of shoulder rumble strip
called the Sonic Nap Alert Pattern (SNAP). A distinct warning sound and vibration are
produced when drowsy or inattentive drivers' vehicles drift so their tires cross this pattern of
recessed grooves along the shoulder of the roadway. Various lengths and depths of grooves
were tested to select a design with enough sound and vibration to be perceptible in a truck
cab and yet not too severe for cars or motorcycles. Design features, testing and initial results
were presented at the TRB Annual Meeting in January 1994. After installation of SNAP, driftoff-road accidents per month decreased by 70 percent. This study reviews those initial
results, adds traffic exposure to compare accident rates per vehicle-distance-traveled,
adjusts for a decline in all accidents during the years considered, and revises the initially
reported accident reduction to 65 percent. Follow-on results are developed for reportable
accidents from 1990-1995, singling out those that could be directly affected by SNAP. About
12 percent of all accidents were considered fully susceptible to SNAP treatment. A reduction
of 60 percent in treatable accidents, or a decline in rate by 2.3 accidents per 100 million
vehicle miles (1.43 per 100 million vehicle kilometers) was documented for 53 segments
totaling 348 mi (560 km) of roadway.
Variable message signing
Effects of weather-controlled variable message signing on driver
behaviour
Author: Pirkko Rämä
Series: VTT Publications 447
Nordic Road & Transport Research No 1 2002
Language: English
The publication is also available as a pdf file on site
http://www.inf.vtt.fi/pdf/publications/2001/P447.pdf
This doctoral thesis summed up six field studies. The concept of weather-controlled speed
limits and displays proved successful. Lowering the speed limit decreased both the mean
speed and the variance of speed. The slippery road condition sign and minimum headway
sign also contributed to safer driving in slippery conditions.
The purpose of the study was to investigate the effects of local and frequently updated
information of adverse weather and road conditions on driver behaviour. The information was
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transmitted by several VMS (Variable Message Sign) types including slippery road condition
signs, minimum headway signs, temperature displays and speed limits.
Variable warnings
For control of the VMS, traffic management centre operators classified the road surface
conditions in three categories based on data from road weather stations. The slippery road
condition sign and the minimum headway sign were controlled manually). The categories
were (a) good, (b) possibly slippery and (c) verified slippery. The slippery road condition sign
was off, in steady mode or in flashing mode, respectively. The minimum headway sign was
always on and the recommended headway depended on vehicle length, driving speed and
road surface condition. The signs were tested at three sites, and the evaluation covered
approximately one year.
The slippery road condition sign and the minimum headway sign improved traffic safety by
decreasing the mean speed in addition to the effect of worsened weather and road condition.
Specifically, the signs decreased the mean speed by 1–2 km/h at a distance of 500–1,100 m
after the signs (Table 1). Earlier research has not shown similar effects for fixed warning or
information signs.
However, the speed effect of the sign was the opposite at one site, suggesting that the sign
may not be effective in all road environments. The effect of the minimum headway sign was
of the same magnitude as the effect of the slippery road sign. In addition, the minimum
headway sign decreased the proportion of short (less than 1.5 seconds) headways in
queues. The slippery road condition sign and minimum headway sign did not substantially
affect the standard deviation of speed.
In a complementary interview study, effects on speed and headways were among the most
frequently reported effects. The interview with drivers who had passed the signs also showed
other potential effects such as refocusing of attention to seek cues on potential hazards,
testing the slipperiness of the road, and more careful passing behaviour.
Figure 1. Schematic diagram showing (a) the slippery road condition sign and (b) the
minimum headway sign (‘suositus’ is Finnish for ‘recommendation’).
Figure 2. Schematic diagram showing a fibre-optic speed limit sign (A1 and B1),
electromechanical speed limit sign (A2), fixed speed limit sign (B2), and general warning sign
with supplemental sign (B3).
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Variable speed limits
On the weather-controlled road including variable speed limits the control of VMS was
automatic. The control categories of the road and weather conditions were good, moderate
or poor. The effects of lowering the posted speed limit on the weather-controlled road were
greater than the effects of the warning and information VMS. In winter, the change of the
speed limit from 100 km/h to 80 km/h decreased the mean speed by 3.4 km/h, whereas
changing the speed limit from 120 km/h to 100 km/h in summer led to a mean decrease of
5.1 km/h. When poor road conditions were difficult to detect, the effect was 2 km/h higher.
Consequently, the system proved to be most effective when adverse weather and road
conditions are not easy to detect, such as black ice conditions when the accident risk is
highest. The system also decreased the standard deviation of speed.
The variable speed limits proved to be more efficient than the warning or information signs
because they affected both the mean speed and the speed variance in the desired direction,
and the speed effect was much greater.
Lowered speed limits due to poor weather and road conditions are on the whole well
accepted. In several roadside interviews, drivers recalled the variable fibre-optic signs
reasonably well. Specifically, 83–91 percent of the drivers recalled the posted speed limit and
66 percent recalled the slippery road sign. Ninety-five percent of the drivers indicated that
variable speed limits are useful.
In conclusion, the concept of weather-controlled speed limits and displays was successful.
The signs were shown to improve traffic safety. However, the effects can not be regarded as
sufficient to compensate for the high accident risk caused by adverse weather and road
conditions.
This calls for more effective measures like in-vehicle speed control. However, a clear
advantage of the VMS is that it provides the same information to all drivers with no
substantial differences in interpretation, thereby contributing also to increased homogeneity
of driver behaviour. The use of effective signs is motivated by the high accident risk on
slippery roads. However, the danger of information overload prevents the use of effective
fibre-optic signs in complex traffic environments. Optimisation of the strength of information
must be taken into account when planning traffic control.
The slippery road condition sign is recommended to be used carefully at critical spots,
whereas a system including variable speed limits is recommended for somewhat longer
problem sections. The use of fibre-optic signs is recommended for weather controlled
applications. The placement of effective variable warning signs has to be considered
carefully. In addition, the findings suggest that it is extremely important to set the variable
speed limits carefully. A sophisticated and error-free data collection and control system is
necessary.
An Evaluation of Dynamic Curve Warning Systems in the Sacramento
River Canyon: Final Report
Authors: Tribbett, Lani, Patrick McGowen and John Mounce
http://www.coe.montana.edu/wti/wwwshare/curve_warning/FINAL%20REPORT.pdf
This report summarizes an evaluation of an advanced curve warning system installed at 5
curves along Interstate 5 in a mountainous portion of rural northern California. Traffic
volumes through the curves are low, ranging from an average daily traffic of 7,650 to 9,300
vehicles. The advanced warning systems consisted of variable message signs installed
before each of the curves displaying warning messages about the upcoming curves. Using
data from a radar unit mounted near the signs, the system also displays the actual speed of
vehicles approaching the curves. Several other alterations to the conditions at the curves
may have influenced the results of the evaluation. The speed limit for passenger cars was
raised from 55 to 65 mph at 3 of the 5 locations. The California Department of Transportation
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added median barriers at 2 locations and the resurfaced the roadway at 2 of the curves. Rain
and wet pavement conditions may also have impacted the speed measurements taken at 2
of the installation sites during the final speed collection visit. The evaluation consisted of a
comparison of speed data gathered before and after installation of the warning system, and
surveys taken approximately 2 months and 10 months after installation. Speed data was
collected using stopwatches to determine the speed of vehicles approaching the curve as
they traveled over measured distances. Speed measurements were collected 9 months prior
to the system's installation and again 2 months, 5 months and 10 months after operation
began. 153 truck drivers completed surveys regarding the system 2 months after it began
operation and 162 completed the second survey, 8 months later. Drivers of passenger cars
completed 89 surveys during the first visit of the evaluation team to a rest area in the
corridor, and 77 completed the survey during the second visit. The report also discusses the
crash statistics for the curve during the 5 years proceeding installation of the warning system,
but the short evaluation period following installation make comparison of accident statistics
invalid
For 3 of the 5 installation sites, the reduction in the speed of trucks traveling through the
curves was statistically significant for at least 1 of the 3 data collection periods after the
warning signs began operation. The two sites that demonstrated a significant reduction in
truck speeds for all three visits after installation had downgrades greater than 5%. The speed
reductions were smaller for the later visits to the sites, possibly indicating the drivers were
becoming accustomed to the signs and paying less attention to them. Passenger vehicles
also demonstrated significant speed reductions at 2 of the 5 curves. One curve recorded
statistically significant speed reductions during the three site visits after installation of the
warning system, while two of the post-implementation visits to the second curve revealed
significant speed reductions.
Survey results indicated that truck drivers in the corridor generally drove it frequently and
were familiar with the curves, while passenger car drivers were most often infrequent
travelers unfamiliar with the curves. 73% of truck drivers responding to the first survey and
70% responding to the second survey indicated that the signs were useful. During the two
visits 76% and 69%, respectively, indicated that they reduced their speed in response to the
signs. 78% of the passenger car drivers responding to the first survey and 85% in the second
survey stated that the system was useful. 60% participating in the first survey and 69% in the
second survey indicated that they reduced their speed in response to the signs. The authors
note a potential flaw in the survey. The number of drivers who reduced their speed in
response to the signs may not accurately represent the effectiveness of the signs because it
fails to assess the impact of the sign on travelers who were already traveling below the
advisory speed displayed on the signs.
The Psychology of Warnings1
Warning signs and labels are everywhere. Many factors are conspiring to fill the world with
more injunctions against our desired behavior.
Unfortunately, warnings often fail to change people's behavior. Either the warning goes
unnoticed, or, as increasingly happens, the warning is seen but ignored.
For many years, designers focused their concern on sensory aspects of warnings: color,
shape, location, pictures vs. text, size and so on. However, recent research suggests that
effective warning design depends as much on the contents of the viewer's head as on the
contents of the warning's message.
People who see a warning must decide whether or not to comply. However, "warning
viewers" (people for whom the warning is intended) are not blanks slates but rather start with
a mental model containing three components. First, the viewer has general knowledge about
the world and how it works. Second, s/he has a set of beliefs and expectations based on
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experience with the same or similar environment, product or technology. Lastly, the viewer
enters the situation with a goal and strategy for achieving that goal. The goal can be specific
("I want to arrive at my destination as soon as possible") or more diffuse ("I want to feel good
about myself"). Understanding what the viewer "brings to the table" is critical for creating
effective warnings.
The Cost-Benefit Analysis
If a warning tells the viewer to refrain from behavior which will enable him/her to easily and
directly achieve a goal, then the viewer makes a cost-benefit analysis.
A driver deciding whether to comply with a speed limit sign might calculate the costs of
arriving later. However, the benefit of compliance is the sense of safety and lowered anxiety
("I won't be as likely to get in an accident," "I won't have to spend time and effort looking for a
radar trap," etc.) There may be other psychological benefits, such as the sense of being "a
good citizen" or "a team player."
The size of the benefits depends on another psychological factor, perception of danger,
which has two components, hazard and risk. Hazard is the "badness" of the possible
outcome. For example, being in a major auto accident is a greater hazard than getting a
speeding ticket. Risk is the probability of the outcome. Being killed by a falling meteorite is
certainly a severe hazard, but it is also a very small danger because the risk probability is
tiny. (Note: much of the research literature confuses the terms risk and danger, using the
term risk to cover both. However, the difference is important for understanding viewer
perception.)
The viewer then must take both hazard and risk into account when making the cost-benefit
analysis. If the person believes that there is great danger, then s/he will see a larger benefit
in compliance. Conversely, perception of small danger means low benefit and compliance
will decrease.
Finally, decision-making factors affect compliance. Two people could make the same costbenefit analysis, but one might ignore the warning and the other doesn't. People accept
different danger levels, have different attitudes about their ability to control danger and are
differentially affected by social and cultural norms.
In sum, people who view a warnings use a mental model to perform a cost-benefit analysis.
The three main process components are 1) cost of compliance, 2) perception of danger level
and 3) personal and social and cultural decision-making factors.
Danger Perception
Perceived danger is the other side of the cost-benefit balance sheet: the greater the
perceived risk and hazard, the greater the likelihood of compliance. Studies have identified
several factors which influence the level of perceived risk.
Familiarization
Viewer history with the product or environment strongly affects danger perception. The
greater the experience with no negative outcome, the lower the level of perceived danger.
To gain compliance, the viewer must be convinced that there is a real personal benefit.
One of the ironies of warnings is that the more experience and skilled the viewer, the
stronger the familiarization effect and the more likely that the warning will be ignored.
Viewers can also acquire familiarization vicariously. You observe other people speeding
without incident, so you might as well, too. Conversely, if a viewer has personal, first-hand
knowledge of people being injured in a situation, then compliance increases.
Risk Taking
When the viewer ignores a warning, it could be because s/he viewed the cost of compliance
as very high or because s/he underestimated the danger. However, studies show that some
people engage in risky actions across a wide variety of circumstances. They likely have a
high tolerance for risk rather than a tendency to underestimate danger in specific
circumstances. Moreover, these risk takers were less likely to comply with warnings. In fact,
the prospect of danger may decrease their compliance because the viewer's goal might
involve courting danger. In some cases, viewers might acknowledge that significant danger
14/24
exists but attempt to control risk by behaving in a "safe" manner. In a sense, they are trying
to perform a "partial compliance" or compromise, where their goal or goal path is modified as
a tradeoff for more safety.
Conclusion
It is imperative to understand what the viewer is trying to achieve and how the warning
affects attainment of his/her goal. Next, the designer must consider the cost-benefit
calculations that the viewer is likely to perform. Finally, the designer must consider the
viewers experience and knowledge and how s/he fits into the social world.
1
A complete version of the article has been published in Occupational Health and Safety Canada.
Avoidance devices test and acceptance
DOT To Test System Designed
To Prevent Run-off-the-Road Crashes
Wednesday, October 31, 2001: The U.S. Department of Transportation (DOT) today
announced the start of an intelligent vehicle operational test of a system designed to help
drivers avoid run-off-the-road crashes. The system warns drivers when they are about to drift
off the road and crash into an obstacle or are traveling too fast for an upcoming curve.
"Too many lives are lost on our nation's highways, and this initiative is another step toward
improving highway safety through the use of new technologies," U.S. Transportation
Secretary Norman Y. Mineta said. "The Intelligent Vehicle Initiative (IVI) system studied in
this test is intended to help save lives and reduce injuries by preventing crashes before they
occur."
The test will involve about 120 drivers, ranging in age from 18 to 70, who will use 10
equipped cars for several weeks each in the Detroit region of southeast Michigan. The test
will last three years, with on-road testing starting in 2003. The test will assess the maturity of
system technology to support its commercial deployment, predict driver acceptance, and
evaluate the safety implications of deployment. The technology warns of an imminent
collision, but the driver retains control of the vehicle. The system operates on straight and
curved paved roads as well as day or night and in light rain.
Run-off-the-road crashes account for more than 20 percent of all police-reported crashes
(1.2 million a year) and more than 41 percent of all in-vehicle fatalities (15,000 a year).
The test system has the potential to prevent run-off-the-road crashes caused by driver
inattention, distraction, drowsiness, and excessive speed.
Partners in the project are the University of Michigan Transportation Research Institute,
Visteon Corp. in Dearborn, MI, and AssistWare Technology, Inc. in Wexford, PA. Navigation
Technologies, a company based in Chicago, will supply the map database, a critical
component of the system. The $18.5 million cost of the test is split between public and
private sector partners. DOT's contribution of $10.5 million is 57 percent of the project's
allocated funding.
The conference report of the fiscal year 2001 Transportation Appropriations Act designated
IVI funding for "an operational test to advance collision avoidance technologies in the light
vehicle platform." IVI is a key component of DOT's Intelligent Transportation Systems (ITS)
program. ITS saves lives, time, and money through combining advanced communications
and transportation technologies to manage and operate transportation systems.
For additional information, visit DOT's ITS Website: http://www.its.dot.gov
Customer acceptance of crash avoidance devices
Charles Rivers Associates Incorporated for the US department of tansportation
Boston 1996
Drowsy drivers detection: responses are positive particularly among the old drivers.
However, there was a good deal of questioning and scepticism about how drowsy dri=vers
detection system would work (for example: questions about contact lenses and sun glasses)
15/24
Guiding systems
The new" road angel gps system from blackspot
Road Angel is designed to provide you with instant critical information to enhance the safety
of your journey. Using the latest GPS technology and the most comprehensive database of
countrywide danger areas, Road Angel compares your position to that of known danger
spots. When nearing a location the units audible alarm sounds and the two tone LCD display
shows the type of hazard and proximity.
Lane Tracking System: "Road Scout"
Road scout lane tracking system determines location and characteristics of a roadway in
real time onboard a moving vehicle
using a camera that looks through the front windshield of a car. The information extracted
is:
- lateral offset of road lines
- angular offset of host vehicle relative to lane
- road curvature
- road incline
- road type (line type, exit ramp, entrance ramp, split lanes, etc.)
Setup of the system is simple and can be used in any vehicle. Lane features are reported
at a rate of 10Hz. Data can be
requested serially by an external computer.
This will be the first system of its type to accurately and reliably track lanes on a highway
and in cities, in daytime as well
as nighttime, and during clear weather and stormy weather. Other lane trackers make false
predictions based on roadway
anomalies such as exit ramps, intersections, and other nearby vehicles. This system
handles all of these cases with no
problems.
Lane Tracking
AURORA
AURORA is a vision-based system designed to warn a wehicle driver of possible impending
road-way departure accidents. It employs a downward looking color video camera with a
wide angle lens, a digitizer, and a portable Sun Sparc workstation. Using a binormalized
adjustable template correlation algorithm, it reliably detects lane markers on structured roads
at 60 Hz. A time-to-lane-crossign (TLC) measurement is calculated for each image based on
the estimation of vehicle-s lateral position and velocity. This measurement is used to trigger
an alarm when the TLC falls below a preset threshold. Promising results have been achieved
under a variety of weather and lighting conditions, on many road types.
A vision roadway based departure warning system
Run-Off-Road Collision Countermeasures program
Robotics Institute
Head: Charles ThorpeCarnegie Mellon University
5000 Forbes Avenue
Pittsburgh, PA 15213
Project Description
Unlike previous Navlab projects, the Run Off Road Collision Countermeasures program is
not aimed at autonomous driving, but rather at driver assist. The goal is to have a computer
vision system monitor the vehicle's position in the lane while a person drives. Then, if the
16/24
person starts to fall asleep and drift off the road, the computer can wake the driver before a
collision occurs. The first phase of this project is now complete. It consisted of statistical
analysis of the accident data to determine the causes of accidents, computer simulations of
accident trajectories to identify the opportunities and times for intervention, prototyping of a
vision system for determining lane position, and experiments in a driving simulator to
measure human reaction to various warning systems.
The results of this first phase are very interesting. Of the nearly 42,000 highway fatalities
each year in the US, nearly 1/3rd of them are caused by single vehicle roadway departures.
Frequent causes of these road departures are driver inattention, driver impairment due to
fatigue or alcohol, and excessive speed, particularly when approaching curves. To combat
these problems, we have developed several prototype collision warning systems. The first,
called RALPH, is a vision system that tracks the vehicle's position in the lane even in
inclement weather. RALPH warns the driver if he begins to drift off the road, or is weaving
excessively due to drowsiness or impairment. The second is a combination GPS and digital
map system, that warns the driver if he is approaching a curve at too high a speed.
The next phase of the project is now under way. This consist of building a new test vehicle,
the Navlab 8, and performing on the road tests. The first set of tests will use RALPH in a
passive mode, to measure typical lane-tracking behavior of several test drivers on a variety
of roads. This will be used to set lane departure warning thresholds low enough to not
generate false alarms, but sensitive enough to provide ample warning. The next set of tests
will involve extended duration tests of the complete warning system, testing both drivers in
the Navlab 8 minivan and professional truckers.
Lane Drift Warning System (LDWS)
Sensors detect :
o vehicle position in lane
o lateral velocity
o upcoming road geometry
Warning algotithm estimates danger of lane departure
Driver interface alerts driver if subsrantial risk of departure
Savetrac
17/24
Intelligent Stability and Handling Systems
Today there are new technologies that are designed to help control your vehicle when you
cannot. We call them intelligent stability and handling systems. Among the newest
automotive safety advancements, they are now available on more and more vehicles as
either optional or standard equipment. Some names for intelligent stability and handling
systems that you may recognize are:
· Active Handling
· AdvanceTrac™
· Dynamic Stability Control
· Electronic Stability Program or ESP
· StabiliTrac
· Traxxar™
Intelligent stability and handling systems provide you with greater control of your vehicle
when loss of control is imminent.
They help you avoid obstacles and prevent the skidding that can occur in all kinds of weather
and on all kinds of roads; conditions in which even the best of drivers might struggle to keep
their cars on the road.
These systems have sensors that detect the direction your vehicle is going and compare it to
the direction you are steering the vehicle. When the system detects a discrepancy between
your intended path and the direction the vehicle is actually travelling, the system will
intervene to help bring the movement of the vehicle back in line with your intentions.
Intelligent stability and handling systems intervene before control is lost by automatically
braking specific wheels. In short, these systems help you maintain control when control might
otherwise - without such a system - be lost.
When the rear wheels of a vehicle lose traction, oversteer can occur. When the front wheels
lose traction, it's called understeer. Either way, the driver can lose the ability to turn the car
along the intended path.
.
When sensors in intelligent stability and
handling systems detect oversteer is
imminent, the outside front wheel brake is
automatically applied to prevent loss of
control.
Likewise, when the sensors detect
understeer is about to occur, they
automatically brake the inside rear wheel,
helping the driver make the turn and
continue forward in the right direction
Intelligent Vehicle Initiative (NHTSA)
http://www.volpe.dot.gov/infosrc/highlts/02/mayjune/d_focus.html
Reducing Motor Vehicle Crashes with the DOT's Intelligent Vehicle
Initiative (NHTSA)
Each year, more than 6 million vehicle crashes occur on our nation's highways. Crashes kill
more than 41,000 people, injure approximately 3.4 million others, and cost more than $150
billion per year. Over the last several decades, public information and education campaigns,
18/24
standard safety equipment, and improved vehicle crashworthiness and highway design have
all contributed to improved safety. Driver error, however, remains the leading cause of
highway crashes. Through the Intelligent Vehicle Initiative (IVI), the DOT hopes to reduce
crashes by helping drivers avoid hazardous mistakes. The goal of the IVI is to accelerate the
development and commercialization of vehicle-based driver assistance products that can
assess the driving environment in ways that drivers cannot. Such products will warn drivers
of dangerous situations, recommend actions, and even assume partial control of vehicles to
avoid collisions, ultimately reducing deaths and injuries.
The Volpe Center supports the DOT's Intelligent Vehicle
Initiative, whose mission is to accelerate the development,
introduction, and commercialization of driver-assistance
products such as Intelligent Cruise Control shown above. Such
products have significant potential benefits.
Helping Drivers Avoid Hazardous Mistakes
Some high-end "smart cars" already have add-ons such as
crash-avoidance systems that maintain a vehicle's position Driver error is the primary
cause of about 90% of reported
in the center of the lane; night-vision capabilities to detect
crashes involving passenger
people, animals, or objects in the dark; and cruise control
that automatically adjusts to maintain a safe distance from vehicles, trucks, and buses.
other vehicles. These and future advanced safety systems The Volpe Center supports the
IVI program in helping drivers
are expected to save lives, to lessen injuries, and to
avoid hazardous mistakes.
reduce financial losses by reducing the number and
severity of vehicle crashes. These safety improvements to
vehicles could also show secondary benefits such as increased transportation mobility,
productivity, and other operational improvements.
IVI products and services will encompass in-vehicle systems such as those mentioned
above; cooperative vehicle-to-vehicle systems, which enable cars to send and receive
information from each other about their relative locations; and cooperative vehicle-toinfrastructure systems such as traffic lights that send information to cars warning them of
upcoming red lights. IVI addresses four types of vehicles: light (passenger) vehicles, transit
and intercity buses, commercial trucks, and specialty vehicles such as emergency and road
utility vehicles. Moreover, the initiative includes the development of industry-wide architecture
and standards, integrated system prototyping, and field operational test evaluations. In this
way, government and industry can assess benefits, define the performance requirements,
and accelerate the deployment of effective driver assistance products and services.
Providing Technical Support to NHTSA in IVI Implementation
ALZIRA Etude sur les alertes et la prévention des accidents
19/24
The Volpe Center has been providing technical support to
Understanding How Crashes
the National Highway Traffic Safety Administration
Happen
(NHTSA) under the IVI for the light vehicle platform since
1999. The Center's studies include: an analysis of different Recognizing that the
development of effective driver
types of crashes (i.e., crossing-path, off-roadway, lane
assistance products requires a
change, and pedestrian and pedalcyclists); an analysis of
rigorous understanding of the
rear-end crashes; an assessment of traffic simulation
collisions themselves, NHTSA
models to evaluate the safety performance of intelligent
asked Volpe to analyze crash
vehicle systems; an analysis of how drivers respond to an
scenarios and identify
imminent rear-end collision when their cars are equipped
potentially effective
with intelligent cruise control systems; a study of
countermeasures.
countermeasures for intersection-crossing-path and offroadway crashes; a traffic safety evaluation framework for
IVI crash countermeasures; and the development of objective test procedures for crash
countermeasure systems. Details of recent analyses of crash types follow.
Lane Change Crashes
Recently, the Center's Accident Prevention Division
completed an analysis of lane change crashes for
NHTSA's Office of Vehicle Safety Research. Lane
change crashes are defined as two-vehicle crashes
that occur when one vehicle encroaches into the
path of another vehicle initially on a parallel path
with the first vehicle and traveling in the same
direction. These crashes include many vehicle
maneuvers such as changing lanes, passing,
Collisions during lane changes and merges
leaving a parking space, drifting, turning, and
account for 1 in 25 of all crashes. Volpe's analysis
merging. The Volpe study, which analyzed lane
of lane change crashes could enable the
development of effective crash-avoidance
change crashes reported in 1999, focuses on a
systems.
selected portion of these crashes to enable the
development of potential lane change, crash
avoidance systems. Dr. Wassim Najm and Mr. John Smith of the Division and Dr. Basav Sen
of EG&G Technical Services (a Volpe contractor) conducted this analysis, which was
completed in February 2002.
Off-Roadway Crashes
Off-roadway crashes occur when a moving vehicle
departs the travel roadway and then experiences a
harmful event. Mr. Jonathan Koopmann and Dr.
Wassim Najm of the Accident Prevention Division
analyzed off-roadway crash countermeasure
systems in support of IVI. They defined off-roadway
crashes and described their pre-crash scenarios
and crash-contributing factors, then used this
information to define countermeasure concepts and
functional requirements for technology to warn
Single-vehicle roadway departures account for 1
drivers of an imminent road edge crossing or a
in 5 of reported crashes. A Volpe team is
vehicle control loss on straight or curved roadways. analyzing countermeasure systems to help
The team performed a technology survey to assess prevent off-roadway crashes, which usually
involve a single vehicle.
the status of applicable state-of-the-art
technologies, and then forecast the progression of
future countermeasure systems. On March 5, 2002, Mr. Koopmann presented this work in a
paper titled "Analysis of Off-Roadway Crash Countermeasures for Intelligent Vehicle
Applications," at the Society of Automotive Engineers World Congress in Detroit, Michigan.
Dr. Najm co-authored the paper.
20/24
Detect Drowsy Drivers
Siemens System
Auburn Hills, Mich. -- Siemens Automotive has devised a system that measures the early
stages of driver fatigue and alerts the driver if they begin to fall asleep at the wheel.
The National Highway Traffic Safety Administration (NHTSA) estimates that approximately
100,000 police reported crashes annually involve drowsiness as a principal causal factor.
Siemens' Drowsiness Detection System links a video camera to an image and signal
processing system that monitors the eye lid movement of the occupant. The system
gathers signals from the driver, processes the responses into measurements of the driver's
blink rate, at which point the algorithm determines if the drowsiness threshold has been
exceeded.
Before an occupant falls asleep, the system recognizes measurable performance
decrements with associated psychophysiological signs, such as a substantial change in
blink rate. This behavioral change allows the system to send a waking signal to the driver.
Warning devices presently being tested include a synthetic voice, a buzzer or alarm,
flashing dome lights, a vibrating steering wheel or gradual bumping of the brakes. These
warning signs should alert the driver that they are in danger of falling asleep and need to
act accordingly to prevent a possible accident caused by drowsiness.
Siemens' Drowsiness Detection System is intended to address the needs of the average
commuter; focusing primarily on long-haul truck drivers, night-time drivers, people driving
long distances alone or people suffering from sleep deprivation.
Unaware of their state of fatigue, drowsy drivers will continue to drive enhancing their
inattentiveness to the road and surrounding conditions. Driver fatigue causes slowed
reflexes, impaired judgment and may lead to an increased number of auto accidents.
Siemens research shows that almost 30 percent of all trucking accidents are caused by
drowsy drivers. The 1995 Federal Highway Administration sponsored Truck and Bus
Safety Summit and other conferences have identified driver fatigue as the top-priority
commercial motor vehicle safety issue.
The Siemens system, which is involved in numerous test pilot programs in the European
trucking industry, is expected to be implemented on a trial basis as early as MY 1999.
Passenger car vehicles may include such a system after the year 2000.
Siemens Automotive is a first-tier supplier capable of providing the international automotive
industry's full spectrum of needs for the most advanced electronics and electrical systems
available to enhance safety, ensure optimum engine control, and ultimately increase
overall driving comfort. Siemens Automotive is a worldwide leader in the design,
manufacture and supply of more than 700 electronic systems and components
Document No. 1094
Siemens Automotive Corporation
Communications Department
2400 Executive Hills Blvd
Auburn Hills, MI 48326
Tel: (248) 209-4000
Fax: (248) 209-5800
Infrastructure Intersection Collision Avoidance
U.S. Department of Transportation
Intelligent Vehicle Initiative
Intersection safety has begun to receive new attention from traffic engineers, human factors
specialists, and others who see that emerging intelligent systems offer significant potential for
improvements (Ferlis, 1999). Crossing path crashes at intersections, as defined by Volpe
(Barr, 2001), involve one vehicle cutting across the path of another, both initially travelling
from either perpendicular or opposite directions, in such a way that they collide.
21/24
Infrastructure-based intersection collision avoidance systems use roadside sensors,
processors, and warning devices; roadside-vehicle communication devices; other roadside
informational or warning devices; and traffic signals to provide driving assistance to
motorists. The intersection collision avoidance systems can be classified as either
infrastructure-only or as infrastructure vehicle cooperative. Infrastructure-only systems rely
solely on roadside warning devices to communicate with drivers.
Cooperative systems communicate information directly to vehicles and drivers. Major
advantages of cooperative systems lie in their capabilities to improve the interface to the
driver, and hence to virtually ensure that a warning is received. This could also take advantage
of the potential to exert control over the vehicle, at least in situations where the system can be
confirmed as reliable and the driver cannot reasonably be expected to take appropriate actions
given the imminent
hazard and response time available.
The investments in roadside sensing and processing of infrastructure-based cooperative
systems will require only a minimal amount of in-vehicle equipment, which will include:
(1)a communications transceiver, possibly based on Dedicated Short Range
Communication
(DSRC) technology;
(2) an in-vehicle processor;
(3) the driver interface.
These functions could be provided through aftermarket devices that might be installed by the
motorist on the vehicle’s windshield or dashboard, similar to a radar detector. Such a device
might only cost $50 in volume. Alternatively, vehicle manufacturers could incorporate these
functions directly at time of manufacture.
This paper describes preliminary concepts for infrastructure-based intersection collision
avoidance systems, briefly assesses their deployment potential, and introduces a partnership
that plans to research, develop, evaluate, and deploy such systems.
SYSTEM CONCEPTS
Four infrastructure intersection collision avoidance system concepts are described here.
Traffic Signal Violation Warning
This countermeasure involves (1) warning potential violators of a traffic signal to recognize
the control device and (2) warning motorists on adjacent approaches of the potential conflict.
The target crashes reflect causal factors of “did not see”, “ tried to beat the light”, or
“deliberate violation”, for a total of 288,000 crashes per year (Barr, 2001).
The basic sensing requirements are to identify potential (very highly likely) violators by
determining the speed and possibly also the deceleration rate of each vehicle at a fixed
location.
Sensing of speed at a point can readily be accomplished with conventional magnetic “loop”
detectors, self-powered vehicle detectors (SPVD), optical sensors, or radar sensors. Sensing
systems capable of measuring deceleration would be more expensive, but could significantly
reduce the number of false detections.
The processing system would identify vehicles at an upstream control point that are unlikely
to stop at the intersection. Preliminary calculations suggest, for example, that a vehicle
traveling 30 mph at a point 100 feet upstream from the stop line will very likely be incapable
of stopping in time (at least without a severe braking event), and hence can be identified as a
potential violator. The processing logic will likely be incorporated in an Advanced Traffic
Controller (ATC), which might represent an upgrade to the signal controller at the
intersection. The ATC would operate the relatively simple algorithm for detecting potential
22/24
violators, and would also monitor the sensors and control the roadside warning devices and
any communication equipment (for a future cooperative system).
Once a violator is identified, warnings will be conveyed to the violator and also to other
drivers on adjacent approaches to the intersection. The violator could be warned by:
(1) Warning signs and lights activated once the potential violation is detected. For example,
“Stop Ahead” warning signs could be used with a flashing amber light to draw attention to the
signs, and located on both sides of the roadway to increase the likelihood that the subject
driver would readily receive the warning.
(2) A warning light could be incorporated directly
in the traffic signal display itself, again to draw attention to the traffic control device.
Forexample, strobe lights have been used to heighten the conspicuity of traffic signal displays
for rural intersections where motorists may not expect a signal.
(3) An intelligent rumble strip could be activated to warn the violator to slow down, and
possibly heighten awareness of the need to stop at the intersection. (4) Variable message signs
(VMS) could convey the warning to the driver.
Motorists on adjacent approaches also need to be warned of the potential violation and
conflict, and could be warned by:
(1) Warning lights activated to indicate a need for caution and possibly to indicate the
source of the conflict.
(2) (2) An intelligent rumble strip activated to warn the other motorists to slow down and
proceed cautiously at the intersection.
(3) (3) A VMS or graphic display sign used to warn drivers of the potential conflict with
the signal violator,
but these might only be effective only where there is sufficient time for the motorists to
comprehend the message and respond.
The costs for specific components needed for an infrastructure-only system are estimated as:
(1) Sensors, at $4,000 per approach.
(2) Controller upgrade, at $3,000.
(3) Warning lights for violators (two per approach) and other drivers (four per approach), at
$200 per light.
If engineering and other construction costs add $8,000, the total costs per intersection can be
estimated as $31,800. Costs for a cooperative system would also include the roadside
transceivers and antennas, and would increase the total costs for an intersection system to
$57,800, exclusive of in-vehicle equipment costs.
Stop Sign Violation Warning
This countermeasure involves (1) warning potential violators of a stop sign to recognize the
control device and (2) warning motorists on adjacent approaches of the potential conflict.
The target crashes reflect causal factors of “did not see” or “deliberate violation”, for a total of
79,000 crashes per year (Barr, 2001).
The basic sensing and processing requirements are similar to those previously described for
traffic signal violations, except that the processing system would likely consist of a
specialized controller, since a standard traffic signal controller will not be available.
Once a violator is identified, warnings will be conveyed to the violator and also to other
drivers on adjacent approaches to the intersection. The violator could be warned by:
(1) Warning signs and lights activated once the potential violation is detected.
(2) A warning light activated adjacent to the “Stop” sign itself, again to draw attention to
the traffic controldevice.
(3) An intelligent rumble strip activated to warn the violator to slow down, and possibly
heighten awareness of the need to stop at the intersection.
23/24
Motorists on adjacent approaches could be warned by:
(1) Warning lights to indicate a need for caution and the source of the conflict.
(2) A VMS to warn drivers of the potential conflict with the stop sign violator.
(3) An intelligent rumble strip.
The costs for specific components needed for an infrastructure-only system are estimated as:
(1) Sensors, at $2,000 per approach (for 6 x 6 foot loops or cameras). (2) Controller and
cabinet, at $4,000. (3) Warning lights for violator (one per approach) and other drivers (four
per approach), at $200 per light. If engineering and other construction costs add $5,000, the
total costs per intersection can be estimated as $21,000. Costs for a cooperative system would
also include the roadside transceivers and antennas, and would increase the total costs for an
intersection system to $47,000.
Traffic Signal Left Turn Assistance
This countermeasure involves warning motorists making a left turn at a traffic signal of a
potential conflict with vehicles approaching from the opposite direction. The target crashes
reflect an “insufficient gap” causal factor, with a total of 192,000 crashes per year (Barr,
2001).
The basic sensing requirements are to identify potential conflicts by determining the speed
and the acceleration or deceleration rate of each vehicle approaching the intersection from the
opposite direction, including vehicles executing through and right turn movements.
Simple point measurements will not be sufficient, since vehicles can assume various
trajectories and acceleration/deceleration/stopping movements, particularly when other
vehicles are present. As a consequence, the sensing of speed and acceleration/deceleration
must be accomplished either with vision-based or radar sensors that can operate over a
sufficiently broad field of regard.
The processor would determine whether each vehicle approaching from the opposite direction
is likely to conflict with a left turn movement by the subject vehicle. The processing system
would likely require an ATC, which might represent an upgrade to the signal controller at the
intersection.
This countermeasure is presumed to apply to intersections with permissive left turn phasing
only, and would convey whether a left turn can be safely initiated. Although the use of
supplemental VMS or other signals could conceivably be considered, a more obvious warning
device is the left turn arrow, modified for its new use. This application may particularly
benefit from cooperative communication, since an in-vehicle system should have many
advantages over roadside intervention methods.
Cooperative intersection collision avoidance systems suggests that an earlier deployment of
cooperative systems might nevertheless be possible. An analysis of the possible impacts of
these collision avoidance systems (Ferlis, 1999) suggested that the systems will likely be
installed first at intersections with relatively poor safety records, so the proportion of crashes
avoided may greatly exceed the proportion of intersections improved. This should further
justify early deployment of these innovative systems.
RESEARCH PARTNERSHIP
The Federal Highway Administration has partnered with the Departments of Transportation of
California, Minnesota, and Virginia to form an Infrastructure Consortium. The Consortium
will represent the interests of state and local highway transportation agencies in the
development and deployment of advanced highway safety technologies. The Consortium will
research, develop, evaluate, and deploy infrastructure and infrastructure-vehicle cooperative
systems, including intersection collision avoidance systems.
24/24
The development of effective intersection collision avoidance systems will require a
significant research effort. The Infrastructure Consortium members agreed that the research
effort would necessarily include tasks to:
(1) analyze crashes and mitigation concepts;
(2) develop intersection collision avoidance concepts and algorithms;
(3) develop analytical models to assess safety countermeasures;
(4) develop or adopt infrastructure-based sensors;
(5) examine human factors issues
(6) define vehicle-infrastructure (or vehicle-vehicle) communication methods
(7) assess benefits, costs, and institutional barriers to deployment
(8) develop in-vehicle systems
There was also agreement that promising concepts would need to be validated through field
operational tests and that design/deployment guidelines would also be needed. The members
of the Infrastructure Consortium are developing a detailed work plan to conduct the research
in partnership with universities in each of the three states, and plan to begin substantive work
in early 2002.
REFERENCES
1. Barr, L.C., daSilva, M.P., and Hitz, J.S. Safety Benefits/Cost Assessment of Potential IVI
Safety Systems. HW00Q Technical Information Exchange. Volpe National
Transportation Systems Center. September 2000.
2. Ferlis, R. Intelligent Transportation Systems, Analysis of Infrastructure-Based System
Concepts, Intersection Collision Avoidance Problem Area. Federal Highway
Administration, U.S. Department of Transportation. December 1999.
3. Hanscom, F.R. Evaluation of the Prince William County Collision Countermeasure
System. Virginia Transportation Research Council, Virginia Department of
Transportation. February 2001.
For further information, contact Bob Ferlis, FHWA at (202) 493-3268 or
[email protected].
October 29, 2001
25/24

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Transcription

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