Post on 09-Jul-2020
Drivers Responses Getting a Better
Number to Use and How to Apply It.
Jeff Muttart, Ph.D.
Crash Safety Solutions, LLC
© Jeffrey W Muttart 2018
Jeffrey W. Muttart, Ph.D.
2018
Symposium on Traffic Safety
© Jeffrey W Muttart 2018
DISCLAIMER
The information contained in this presentation is, to the best of our knowledge, authentic and reliable; the author gives no guarantee that he has exactly paraphrased prior research. The author acknowledges that other factors and procedures not discussed in this class may affect your conclusions and interpretation of these results.
We cannot teach you in one week what it took years to learn – this presentation is a very small sample and should be treated as a starter.
ACKNOWLEDGMENTSI would like to thank all those who have assisted in my research. This includes all co-authors, colleagues,
and professors at the Universities of Hartford and Massachusetts. I would also like to give credit to my
colleagues at Crash Safety Research Center, LLC including Lisa Ton, Erin Strout, Lynn Carangelo and
Swaroop Dinakar.
© Jeffrey W Muttart 2018
Copyright
These materials may be used by only the person who paid for attendance, or purchased the materials.
Thus, the materials are for a single user only.
Use of any part of this course material for any purpose other than reconstructing and investigating motor vehicle crashes by the single user is prohibited. No derivative works are allowed.
Therefore, do not use this material to…
teach a class,
write a study or article,
for any other purpose without the written permission of the author.
No materials herein may be shared without written permission. These materials are the intellectual property of CSS, LLC. If someone wishes to purchase these materials, please contact info@crashsafetysolutions.com
The cost for these materials is $100 per user unless provided as part of an authorized course of study provided by, or sponsored by CSS, LLC.
© Jeffrey W Muttart 2018
Correct application of
perception-response times
FOCUSING OUR ATTENTION ON THE RESEARCH OF DRIVERS RESPONSES TO EASILY IDENTIFIED IMMEDIATE HAZARDS (EMERGENCY RESPONSES)
© Jeffrey W Muttart 2018
Problem
Problems
“blanket” or “abstract” 1.5 seconds – not associated with THIS case
Unknown starting point (road edge, stop line, when 1st seen)???
Unknown end – 1st reaction? Brake reaction? Up to 0.4 g, up to 0.7 g???
In 2017, there were several Daubert hearings related to PRT
“…a blanket PRT of 1.5 seconds – such as was used by ##### in his analysis – was overly simplistic and inappropriate under the circumstances because PRT is a discipline that is very dependent on the specific environment and hazard presented to a particular driver.”
Must used accepted research
Must apply the research properly to the facts of the caseBlame a
similar study
PRT ~ Info to
driver
© Jeffrey W Muttart 2018
Musical ScaleGood information versus bad information
DIFFERENCE BETWEEN EXPECTED AND UNEXPECTED IS
BASED UPON INFORMATION!!!
© Jeffrey W Muttart 2018
More information is good
until….
Information… more
is better
Capabilities
Until we get too
much
BAD! BAD!
Minimum Threshold
© Jeffrey W Muttart 2018
Example of too much
information
Average PRT 0 to ∞
Normal range (Standard
deviation)
Texting
Add 0.7 s
(If they respond at all)
Minimum
necessary
Information for
recognition
Ped dart out when negotiating a curve or
intersection when involved in a hands
free argument
Text messaging and responding to an
unexpected hazard
© Jeffrey W Muttart 2018
© Jeffrey W Muttart 2018
Example of too little
information
Also, Pedestrian
dressed in black at night
Vehicle stopped facing forward in travel
lane on high speed highway
CANNOT apply PRT…
Cannot respond to something
That is unrecognizable
Minimum necessary
Information for
recognition
Vehicle or pedestrian more than 8 feet from road edge
© Jeffrey W Muttart 2018
Problem – so you know?
1. What is PRT and what phases are included?
2. When does PRT start?
3. When does PRT end?
4. How each of the above might change for
different crash types?
5. Otherwise… you are
6. Making up!
© Jeffrey W Muttart 2018
Each crash type should be
addressed separately
Path Intrusions:
Lead vehicle:
Lead vehicle stopped < 2 seconds
Lead vehicle stopped > 2 seconds
Lead vehicle traveling slower
Lead vehicle decelerating
CSRC, LLC Added Crash Types
??Human
error??
?? Human
limitation??
Both high speed
86S 88S
National Motor Vehicle Crash Causation Study Crash Types
© Jeffrey W Muttart 2018
Response to a vehicle
ahead
© Jeffrey W Muttart 2018
driver error - slips or errors of
execution or mistakes
Information? – Sudden change in following distance
Brake lights, traffic slowing, = BRAKE STUPID!
© Jeffrey W Muttart 2018
Naturalistic data from Muttart, 2003, 2005
N
PRT
(AVG)
PRT
(Median) 85th Percentile Crashes Nighttime
Routine
Rear-end 13 1.1 s 1.0 s 1.3 s 7 2
(not looming)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.6 s. 0.7 s. 0.8 s. 0.9 s. 1.0 s. 1.1 s. 1.2 s. 1.3 s. 1.4 s. 1.5 s. 1.6 s. 1.7 s. 1.8 s. 1.9 s. 2.0 s.
Low Speed Rear End & Close Following
Perception-Response Times (Day & Night)
30.7% - < 1.0 s
61.5% - 1.0 – 1.31 s
7.7% - > 1.32 s
© Jeffrey W Muttart 2018
Driver Response Times
Car Following Situations
Headway & Topography
Headway (seconds)
> 3.51.1 - 3.5< 1.1
Mea
n R
esp
on
se
Tim
e (
ms
.)
4000
3000
2000
1000
0
Straight & Level
Curves & Intersect.
1225
9291064
3118
1645
1001
Closing Speed is not at issue
at intersections
Muttart, Messerschmidt & Gillen, 2005
© Jeffrey W Muttart 2018
Human error - (Inability to
detect or diagnose closing speed)
© Jeffrey W Muttart 2018
Looming: > 40 mph Closing
on Straight Multi-lane Road
Average driver starts maneuver ~ 120 ft (36.6 m)
This driver was better than that
© Jeffrey W Muttart 2018
Path Intrusion Information
factors to consider
Information Factor A B
Where was hazard Directly ahead Right or left or ahead
Natural lighting Day Night
Movement Target was always
moving
Target was stationary
Topography Intersection, or area
where there was a
greater conflict
Straight road or
highway
Which scenarios offer drivers the least information?
© Jeffrey W Muttart 2018
Previously obstructed
Hazard 1st seen in the
roadSTART: APPROXIMATELY ½ THE OBJECT IS RECOGNIZABLE (3 FT OF FRONT)
END: BRT – BRAKING; PRT - ~0.4 G
AVERAGE PRT (PERCEPTION-RESPONSE TIME = 1.0 SEC +/- 0.36 SEC
85% OF DRIVERS RESPOND FASTER THAN 1.4 SEC
95% OF DRIVERS RESPOND FASTER THAN 1.7 SEC
© Jeffrey W Muttart 2018
What if the Principle Other Unit is
Already In the Road When First Seen?
Pupil SizeFixation
Location
Car
© Jeffrey W Muttart 2018
When to Start the PRT
Clock
© Jeffrey W Muttart 2018
Pre-recognition
© Jeffrey W Muttart 2018
Recognition
© Jeffrey W Muttart 2018
From between cars - day
© Jeffrey W Muttart 2018
Steers Left / Brakes 1.0 s later
Average = 1.0 s +/- 0.36 s
© Jeffrey W Muttart 2018
References: Sudden
appearing path intrusion Chisholm, S.L., Caird, J.K., Teteris, E., Lockhart, J., &
Smiley, A. (2006). Novice and experienced driving performance with cell phones. Proceedings of the 50th Annual Human Factors and Ergonomics Meeting, San Francisco, CA, October 2006. pp. 2354-2358.
D'Addario, P.M. (2014). Perception-Response Time to Emergency Roadway Hazards and the Effect of Cognitive Distraction, Master's Thesis. University of Toronto.
Jurecki, R., Stanczyk, T.L., (2011). The test methods and the reaction time of drivers, Eksploatacja I Niezawodnosc, 3, 16-23.
Stanczyk, T.L., Jurecki, R., Jaskiewicz, M., Walczak, S., Janczur, R. (2011). Researches on the Reaction of a Pedestrian Stepping into the Road from the3 Right Side from Behind an Obstacle Realized on the Track, Journal of KONES Powertrain and Transport, 18,(1), 615-622.
© Jeffrey W Muttart 2018
Rule of Thumb PRTs
Crash type Start End PRT
Sudden slowing LV Brake lights of LV or 0.006 r/s 0.4 g 1.0 +/- .32 s
High speed closing Looming threshold 0.4 g Expect ~ 120 ft of hard braking or
steering
Sudden appearance 3 ft. / 1 m of target in sightline 0.4 g 1.0 +/- .36 s
Requirements with all PRTs
- EASILY identifiable
- Know what it is
- Know where it is
- know that it is headed directly toward path
- Requires an emergency response
When were brakes applied?
Subtract 0.25 s Ising, et al., 2012
Mazzae et al., 1999
Muttart, 2003, 2005
Goudie et al. (SAE)
© Jeffrey W Muttart 2018
Left turn or through
movement intruderSTART: VEHICLE: STOP LINE OR SIMILAR LOCATION
PEDESTRIAN: .5 M (1.5 FT) FROM ROAD EDGE (I.E. , CURB)
END: BRT – BRAKE; PRT - ~0.4 G
© Jeffrey W Muttart 2018
Path Intrusion
An object that is traveling or facing a different
direction than the subject driver and enters the
driver’s path
Primary Factors
1. Intersection vs.
straight road
2. Eccentricity
1. How many
lanes
2. How fast is
the intruder
3. PRT, BRT, pRT???
4. Manual
secondary task
NOT Factors
1. Headway
2. Lanes
© Jeffrey W Muttart 2018
Side intrusion starting from
a near road edge/stop
lineDay Night
Straight 1.34 sec 1.80 sec
Curve, cued,
intersection
1.55 sec 2.05 sec
Plus or minus 35%
More information
to the driver
Less information
to the driver
© Jeffrey W Muttart 2018
Path Intrusion Intersection
Night – 1.6 seconds works!
© Jeffrey W Muttart 2018
1.6 s later – the only common crash
type where 1.5 - 1.6 s is correct
© Jeffrey W Muttart 2018
Pedestrian Intrusion –
Intersection - day
© Jeffrey W Muttart 2018
0.8 s – hard braking
© Jeffrey W Muttart 2018
0.8 s – hard braking
Expected ~ 1.1 s +/- 0.4 s
© Jeffrey W Muttart 2018
Straight road – dayAverage PRT – 1.8 sec
85% respond faster than 2.4 sec
95% respond faster than 3.0 sec
© Jeffrey W Muttart 2018
This driver’s PRT ~ 3.2 sec(much slower than average)
© Jeffrey W Muttart 2018
Path IntrusionPEDESTRIANS
© Jeffrey W Muttart 2018
Barrett et al 1968
- Started response time
when pedestrian
emerged from a
roadside shed
© Jeffrey W Muttart 2018
Started at the last landing foot before
entering road
© Jeffrey W Muttart 2018
One study started the
clock at the wallWhen PRT was measured as described earlier, Lubbe = IDRR
Lubbe et al, 2015 Intersection – day – expect BRT = 1.1 s –
he reported 1.4 s can you explain why he was higher?
PRT =
1.1 s
From
here
BRT =
1.4 s
© Jeffrey W Muttart 2018
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0 s. 0.5 s. 1.0 s. 1.5 s. 2.0 s. 2.5 s. 3.0 s.
Intersection Path intrusion – f/ Different Direction
Day Night
Naturalistic data from Muttart, 2003, 2005
(Other unit started from stop: Day 19; Night 7)
N PRT SD CV Crashes
Eccentricity > 12 deg.
(2 lanes)
Day 30 1.42 0.51 0.33 12 11
Night-lighted 16 1.56 0.73 0.41 8 9
MeanCV 0.36
© Jeffrey W Muttart 2018
References: Vehicle path
Intrusions Chang, S,H., Lin, C. Y., Fung, C., P., Hwang, J. R., and Doong, J., L. (2008). Driving
performance assessment: Effects of traffic accident location and alarm content, Accident Analysis and Prevention, 40, 1637-1643.
D'Addario, P.M. (2014). Perception-Response Time to Emergency Roadway Hazards and the Effect of Cognitive Distraction, Master's Thesis. University of Toronto.
Hankey, J. M., McGehee D. V., Dingus, T. A., Mazzae, E. N., & Garrott, W. R. (1996). Initial driver avoidance behavior and reaction time to an unalerted intersection incursion, Proceedings of the Human Factors and Ergonomics Society 40th Annual Meeting.
Mazzae, E. N., Barickman, F., Baldwin, G. H. S., & Forkenbrock, G. (1999). Driver crash avoidance behavior with ABS in an intersection incursion scenario on dry versus wet pavement. (SAE Paper No. 1999-01-1288) Warrendale, PA; Society of Automotive Engineers.
Lechner, D., & Malaterre, G. (1991). Emergency maneuver experimentation using a driving simulator. (SAE Paper No. 910016) Warrendale, PA: Society of Automotive Engineers.
Mazzae, E. N., Baldwin, G. H. S., & McGehee, D. V. (1999). Driver crash avoidance behavior with ABS in an intersection incursion scenario on the Iowa driving simulator. (SAE paper No. 1999-01-1290) Warrendale, PA; Society of Automotive Engineers.
Perron T., Chevennement J., Damville A., Mautuit C., Thomas C., Le Coz J.Y. (1998). Pilot Study of Accident Scenarios on a Driving Simulator, Proceedings of the 16th ESV Conference, June 1-4, 1998, Windsor, Canada, Paper n° 98-S2-O-02, pp. 374-385.
© Jeffrey W Muttart 2018
References: Pedestrian
path Intrusions Barrett, G., Kobayashi, M., & Fox, B. H. (1968). Feasibility of studying
driver reaction to sudden pedestrian emergencies in an automobile simulator, Human Factors, 10, 19-26.
Broen, N. L., & Chiang, D. P. (1996). Braking response times for 100 drivers in the avoidance of an unexpected obstacle as measured in a driving simulator, Proceedings of the Human Factors and Ergonomics Society 40th Annual Meeting, 900.
Fisher, D. L., Knodler, M., & Muttart, J. (2009). Driver-Eye-Movement-Based Investigation for Improving Work-Zone Safety. The New England Transportation Consortium. Project No. NETC 04-2.
Phelps, N. R., & Dunne, M. C. (2001). Factors that influence driver reaction times on a PC-based test, Proceedings of the 2001 Annual Conference of the Institute of Traffic Accident Investigators. 109-115.
Lubbe, N., Rosen, E. (2014). Pedestrian crossing situations: Quantification of comfort boundaries to guide intervention training, Accident Analysis and Prevention, 71, 261-266.
Lubbe, N., Davidson, J. (2015). Drivers' comfort boundaries in pedestrian crossing: a study in driver braking characteristics as a function of pedestrian walking speed, Safety Science, 75, 100-106. doi:10.1016/j.ssci.2015.01.019
© Jeffrey W Muttart 2018
Rule of Thumb PRTsCrash type Start End PRT
Sudden slowing LV Brake lights of LV or 0.006 r/s 0.4 g 1.0 +/- .32 s
High speed closing Looming threshold 0.4 g
Expect ~ 120 ft
of hard braking
or steering
Sudden appearance 3 ft. / 1 m of target in sightline 0.4 g 1.0 +/- .36 s
Straight – day *(lane side)
Ped – 1.5 ft (0.5 m) before curb
Vehicle – stop line or 6.5 ft (2 m) from
curb (edge of road)
0.4 g 1.8 +/- .63
Straight –night* 0.4 g 2.1 +/- .71
Intersection/cued – day* 0.4 g 1.3 +/- .51
Intersection/cued – night* 0.4 g 1.6 +/- .73
When were brakes applied?
Subtract 0.25 s Ising, et al., 2012
Mazzae et al., 1999
Muttart, 2003, 2005
Goudie et al. (SAE)
© Jeffrey W Muttart 2018
Where to start PRTWHAT IS STARTING FROM STOP… INTRUDER INITIALLY SLOW
WHAT IF INTRUDER IS COMING IN HOT! – SHOULD DRIVER RECOGNIZE THIS BEFORE INTRUDER REACHES STOP LINE?
© Jeffrey W Muttart 2018
If I wanted to measure the
time to fill a cup, would it
matter where I start?
Start
1.3 sec
2.5 sec
End
Study
A
Study
B
© Jeffrey W Muttart 2018
Study: Time to fill cupWhich study (A or B) best applies?
~ stop line ~ sudden appearance in road
Estimate the time it would take to fill each cup
© Jeffrey W Muttart 2018
Start at one of three locations
All 3 Experimenters stop the clock
here… when brake lights go on
C
B
A
Experimenter C starts the clock here
Experimenter A starts the clock here
Experimenter B starts
the clock here
DO NOT use a PRT that started at B to a starting point at A
or C
All Response Times are Not
The Same
© Jeffrey W Muttart 2018
Two phase stop – Consistent
with Harwood et al.
© Jeffrey W Muttart 2018
CDL Driver - Two phase
stop – secondary glance
© Jeffrey W Muttart 2018
High speed intrusionBOTH VEHICLES ENTER THE INTERSECTION AT SPEED
EXPECT 0.4 TO 0.7 SECONDS OF PRE-IMPACT BRAKING AND MOST WILL CRASH
© Jeffrey W Muttart 2018
What if a car comes in without
slowing? Do we recognize it earlier?... NO!
We assume drivers will obey the law.
© Jeffrey W Muttart 2018
Anticipation (hope?) – that side road drivers will stop
© Jeffrey W Muttart 2018
Braking 0.3 s before impact
© Jeffrey W Muttart 2018
Anticipation (hope?) – that side road drivers will stop
© Jeffrey W Muttart 2018
Braking 0.3 s before impact
© Jeffrey W Muttart 2018
Marshall et al, 2017; Perron
et al., 1998
Greater
eccentricity
Accounts for
Expectation that
Other driver will
obey the law
6.1 sec2.5 sec
Marshall Perron
POU Speed 45 mph 60 km/h – 37.3
mph
Visible 2.49 s 6.1 s
Warning at 1.2 s
before visible
Speed reduction
(median)
Not mentioned 5 km/h (3 mph)
Median response
before impact
0.4 s 0.7 s
Crashed 91% 89%
AT SPEED INTRUSIONS –
PRTs are fast,
but not fast
enough
© Jeffrey W Muttart 2018
References: High speed
path Intrusion Chang,S,H., Lin, C. Y., Fung, C., P., Hwang, J. R., and
Doong, J., L. (2008). Driving performance assessment: Effects of traffic accident location and alarm content, Accident Analysis and Prevention, 40, 1637-1643.
Marshall, D., Brown, T., Boyle, L.N., Wu, X. (2016). Connected vehicle alerts: One size doesn't fit all scenarios, Transportation Research Board Annual Meeting.
Perron T., Chevennement J., Damville A., Mautuit C., Thomas C., Le Coz J.Y. (1998). Pilot Study of Accident Scenarios on a Driving Simulator, Proceedings of the 16th ESV Conference, June 1-4, 1998, Windsor, Canada, Paper n° 98-S2-O-02, pp. 374-385
© Jeffrey W Muttart 2018
Rule of Thumb PRTsCrash type Start End PRT
Sudden slowing LV Brake lights of LV or 0.006
r/s
0.4 g 1.0 +/- .32 s
Sudden appearance 3 ft. / 1 m of target in
sightline
0.4 g 1.0 +/- .36 s
Straight – day *(lane side) Ped – 1.5 ft (0.5 m) before
curb
Vehicle – stop line or 6.5 ft
(2 m) from curb (edge of
road)
0.4 g 1.8 +/- .63
Straight –night* 0.4 g 2.1 +/- .71
Intersection/cued – day* 0.4 g 1.3 +/- .51
Intersection/cued – night* 0.4 g 1.6 +/- .73
High speed Intrusion Stop line or 6.5 ft (2 m)
from curb (edge of road)
0.4 g 0.8 +/- .7 sSpeed/
Accuracy
When were brakes applied?
Subtract 0.25 s Ising, et al., 2012
Mazzae et al., 1999
Muttart, 2003, 2005
Goudie et al. (SAE)
• See previously stated
requirements For PRT
© Jeffrey W Muttart 2018
Path Intrusion from same
directionVEHICLE CHANGING LANES OR CUT-OFF
START: 1ST LATERAL MOVEMENT OF THE INTRUDER
END: BRT-BRAKING; PRT – 0.4 G
© Jeffrey W Muttart 2018
Sideswipe - same
A VEHICLE that is traveling the same
direction as the subject driver and enters
the driver’s path
Primary Factors
1. No. Lanes
changed
2. Eccentricity
1. How many
lanes
2. How fast is the
intruder
traveling
3. Day versus night
NOT Factors
1. Headway
2. Intersection vs.
straight road
© Jeffrey W Muttart 2018
Path Intrusion from same
direction vehicle (Cut-off)
© Jeffrey W Muttart 2018
Noticeable deceleration
1.2 seconds –
how did he compare?
© Jeffrey W Muttart 2018
Path Intrusion - Principle Other from Same Direction
MeanCV = 0.35
N PRT SD CV Crashes
Day-Next lane 24 0.93 0.34 0.37 10
Day - >1 lane 28 1.13 0.41 0.37 20
Night - Next lane 6 1.32 0.49 0.37 1
Night - > 1 lane 22 1.40 0.45 0.32 11
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0 s. 0.5 s. 1.0 s. 1.5 s. 2.0 s. 2.5 s. 3.0 s.
Path Intrusion from Same Direction: Cut-off
Naturalistic data from Muttart, 2003, 2005
© Jeffrey W Muttart 2018
References: Path Intrusion
from same direction (cut-off) Chen, W-H, Fung, C-P, Chang, C-C, (2005). Study of
Driver Behavior as Motorcycles Mixed in Traffic Flow. Downloaded 12/29/09. http://www-nrd.nhtsa.dot.gov/pdf/esv/esv19/05-0296-O.pdf
Chisholm, S.L., Caird, J.K., Teteris, E., Lockhart, J., & Smiley, A. (2006). Novice and experienced driving performance with cell phones. Proceedings of the 50th Annual Human Factors and Ergonomics Meeting, San Francisco, CA, October 2006. pp. 2354-2358.
Currie, L. (1969). The perception of danger in a simulated driving task, Ergonomics, 12, 841-849.
Muttart, J. W. (2003). Development and evaluation of driver perception-response equations based upon meta-analysis, (Technical paper no. 2003-01-0885). Warrendale, PA: Society of Automotive Engineers.
© Jeffrey W Muttart 2018
Rule of Thumb PRTsCrash type Start End PRT
Sudden slowing LV Brake lights of LV or 0.006 r/s 0.4 g 1.0 +/- .32 s
Sudden appearance 3 ft. / 1 m of target in sightline 0.4 g 1.0 +/- .36 s
Straight – day *(lane side)
Ped – 1.5 ft (0.5 m) before curb
Vehicle – stop line or 6.5 ft (2 m) from
curb (edge of road)
0.4 g 1.8 +/- .63
Straight –night* 0.4 g 2.1 +/- .71
Intersection/cued – day* 0.4 g 1.3 +/- .51
Intersection/cued – night* 0.4 g 1.6 +/- .73
High speed IntrusionStop line or 6.5 ft (2 m) from curb (edge
of road)0.4 g 0.8 +/- .7 s
Same direction day - next lane
First lateral movement that lead directly
to the intrusion
0.4 g 0.9 +/- .34
Same direction day - 2 lanes 0.4 g 1.1 +/- .41
Same direction night - next lane 0.4 g 1.3 +/- .49
Same direction night – 2 lanes 0.4 g 1.4 +/- .45
When were brakes applied?
Subtract 0.25 s
• See previously stated
requirements For PRT
© Jeffrey W Muttart 2018
Left turn across path-opposite
direction / head-on / U-turnSTART: 1ST LATERAL MOVEMENT THAT LEADS TO THE
INTRUSION
END: BRT – BRAKE; PRT - ~0.4 G
© Jeffrey W Muttart 2018
D’Addario, 2014
Brake Resp Time = 2.05 s
Perception-Response Time to Emergency Roadway Hazards and the
Effect of Cognitive Distraction, Master’s Thesis, U. of Toronto
© Jeffrey W Muttart 2018
LTAP-OD Day – No
Intervening vehicle
© Jeffrey W Muttart 2018
LTAP-OD – Day – No Intervening vehicle 2.2 s
Average 1.8 s +/- 0.5 s (See D’Addario, 2015)
© Jeffrey W Muttart 2018
1st lateral movement to
start of steering = 1.8 s
© Jeffrey W Muttart 2018
Head-onStart- 1st lateral movement OR when it is clear
the vehicle is in lane – whichever is last
© Jeffrey W Muttart 2018
U-Turn
© Jeffrey W Muttart 2018
References
Hancock, P.A., DeRidder, S.N., (2003). Behavioural accident avoidance science: understanding response in collision incipient conditions, Ergonomics, 46, 1111-1135.
Unbeknownst to each driver, another live subject driver was approaching head-on in daylight at an average closing speed of near 72.1 mph.
From 1st visible over crest, steer response times were an average of 1.65 +/- 0.17 second.
Steering time was approximately 0.38 second
D’Addario, P. (2014). Perception-Response Time to Emergency Roadway Hazards and the Effect of Cognitive Distraction, Master’s Thesis, U. of Toronto
© Jeffrey W Muttart 2018
Rule of Thumb PRTs Crash type Start End PRT
Sudden slowing LV Brake lights of LV or 0.006 r/s 0.4 g 1.0 +/- .32 s
Sudden appearance 3 ft. / 1 m of target in sightline 0.4 g 1.0 +/- .36 s
Straight – day *(lane side)
Ped – 1.5 ft (0.5 m) before curb
Vehicle – stop line or 6.5 ft (2 m) from curb (edge of
road)
0.4 g 1.8 +/- .63 s
Straight –night* 0.4 g 2.1 +/- .71 s
Intersection/cued – day* 0.4 g 1.3 +/- .51 s
Intersection/cued – night* 0.4 g 1.6 +/- .73 s
High speed Intrusion Stop line or 6.5 ft (2 m) from curb (edge of road) 0.4 g 0.8 +/- .7 s
Same direction day - next lane
First lateral movement that lead directly to the
intrusion
0.4 g 0.9 +/- .34 s
Same direction day - 2 lanes 0.4 g 1.1 +/- .41 s
Same direction night - next lane 0.4 g 1.3 +/- .49 s
Same direction night – 2 lanes 0.4 g 1.4 +/- .45 s
Left turn from opposite direction / Head-on / U-turnsFirst lateral movement that lead directly to the
intrusion0.4 g Use straight road PRT
High speed closing Looming threshold 0.4 gExpect ~ 120 ft of hard
braking or steering
When were brakes applied?
Subtract 0.25 s • See previously stated
requirements For PRT
© Jeffrey W Muttart 2018
Want to be more precise
than rule-of-thumb? Learn when PRT cannot be used
Night recognition
CAPLETS
Contrast
Anticipation (relevance, experience, shape of object,…)
Account for more variables
Rules of thumb are very general
PRT will vary from Rules of thumb
Driver attention
Visual angle of the target
Speed of intruder
When the driver’s foot already rests on the brake
When not driving
When the driver knows what is coming (almost never in real-life)
© Jeffrey W Muttart 2018
Nighttime Recognition CONTRAST
ANTICIPATION
PATTERN
LIGHTING
ECCENTRICITY
TIME OF EXPOSURE
SIZE
CAPLETS
Information necessary
for recognition
© Jeffrey W Muttart 2018
High & Low Beam
Headlight aim (SAE J599)Left headlight
position
Peak Illumination
© Jeffrey W Muttart 2018
Nighttime Recognition Distance Unlit Open Roads
(test track tests result in much greater distances)
© Jeffrey W Muttart 2018
Balk, S. A., Tyrrell, R. A., Brooks, J. O., Carpenter, T. L., (2008). Highlighting human form and motion informationenhances the conspicuity of pedestrians at night, Perception, 37, 1276 – 1284.
No pattern & below
threshold –no
movement
Pattern created by only when
moving
Pattern & Movement
= easily identifiable
© Jeffrey W Muttart 2018
Pattern / Size
More information – A well marked trailer
ahead– or the underside of a trailer across the
road
Deceleration
started 1.62
sec before
impact
© Jeffrey W Muttart 2018
© Jeffrey W Muttart 2018
0.75 Sec. Before Impact
© Jeffrey W Muttart 2018Photo supplied by W. Cover
© Jeffrey W Muttart 2018
Family with Flashlight
© Jeffrey W Muttart 2018
Generally, age has made a difference
But what about THIS driver?
OlderYoungerNumber
Response Time
Theoretical distribution of responses for young
versus old driver participants.
This
Driver?
© Jeffrey W Muttart 2018
Summary of PRT / Night
RecognitionDRIVERS’ RESPONSES VARIED DUE TO ACTIONABLE
INFORMATION TO THE DRIVER
© Jeffrey W Muttart 2018
Rule of Thumb PRTs Crash type Start End PRT
Sudden slowing LV Brake lights of LV or 0.006 r/s 0.4 g 1.0 +/- .32 s
Sudden appearance 3 ft. / 1 m of target in sightline 0.4 g 1.0 +/- .36 s
Straight – day *(lane side)
Ped – 1.5 ft (0.5 m) before curb
Vehicle – stop line or 6.5 ft (2 m) from curb (edge of
road)
0.4 g 1.8 +/- .63 s
Straight –night* 0.4 g 2.1 +/- .71 s
Intersection/cued – day* 0.4 g 1.3 +/- .51 s
Intersection/cued – night* 0.4 g 1.6 +/- .73 s
High speed Intrusion Stop line or 6.5 ft (2 m) from curb (edge of road) 0.4 g 0.8 +/- .7 s
Same direction day - next lane
First lateral movement that lead directly to the
intrusion
0.4 g 0.9 +/- .34 s
Same direction day - 2 lanes 0.4 g 1.1 +/- .41 s
Same direction night - next lane 0.4 g 1.3 +/- .49 s
Same direction night – 2 lanes 0.4 g 1.4 +/- .45 s
Left turn from opposite direction / Head-on / U-turnsFirst lateral movement that lead directly to the
intrusion0.4 g Use straight road PRT
High speed closing Looming threshold 0.4 gExpect ~ 120 ft of hard
braking or steering
When were brakes applied?
Subtract 0.25 s • See previously stated
requirements For PRT
© Jeffrey W Muttart 2018
Nighttime Recognition Distance Unlit Open Roads
(test track tests result in much greater distances)