Behaviour of Road Users at Behaviour of Road Users at Development - - PDF document

Behaviour of Road Users at Behaviour of Road Users at Unsignali Unsignaliz zed Pedestrian Crossings ed Pedestrian Crossings in Poland in Poland

Piotr Olszewski, Witold Czajewski, Paweł Dąbkowski, Piotr Szagała Warsaw University of Technology Warsaw University of Technology Ilona Buttler Motor Transport Institute Motor Transport Institute

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Research Project MOBIS:

„Development of a method for assessing safety of pedestrian crossings using automatic video analysis” Consortium: Warsaw University of Technology, Motor

Transport Institute, Neurosoft Ltd.

Financing by Polish „National Centre for Research and Development” (Applied Research Programme) Time frame: 3 years 2012 – 2015

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Problem significance

Pedestrian road safety situation in Poland (2014):

– 1116 pedestrians killed (35% of all traffic fatalities) – 8398 pedestrians injured (20% of all traffic injuries)

During 6 years (2008-2013):

– 13% pedestrians were killed and – 26% were injured at unsignalized zebra crossings

Road safety situation is generally improving Accidents at pedestrian crossings have not decreased in the last 4 years

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Field surveys and tests

Aim: development of a method for assessing the safety of pedestrians using automatic video analysis Basis: identification of dangerous encounters (traffic conflicts - events which could lead to an accident) between vehicles and pedestrians Assessments based on surrogate measures can hopefully use relatively short observation periods During the project, four field tests were conducted at different crossings, using different safety improvement measures

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Test site POW in Warsaw

Zebra crossing with pedestrian refuge in the middle 4-lane 2-way road Temporary installation of SignFlash system – yellow lights flashing after detecting a pedestrian

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Test sites in Wrocław (CEN, SWO)

2 zebra crossings near tram stop 2-lane 2-way road Installation of system Levelite – LED lights embedded in pavement

CEN direction: continuous blinking SWO direction: blinking after pedestrian detection

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Data collection

Site Period No of days with video recording No of days selected for analyses Safety measure used from to Warsaw POW 23.09.2013 19.12.2013 49 23 SignFlash (SF) Wrocław CEN 01.08.2014 27.11.2014 103 18 LeveLite (LL)

Video recording system: an overview camera plus one directional camera per lane, terminal Only days with good conditions (no shadows, no traffic jam) were selected for processing

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Video data analysis

Motion trajectories of vehicles and pedestrians were determined based on video processing. Several parameters describing pedestrian-vehicle encounters were calculated, such as:

Speed profile of pedestrians at the zebra Speed profile of vehicles (30 m approach to zebra) Vehicle deceleration (average) Minimum distance between event participants PET value

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Classification of vehicle-pedestrian encounters

A1 - vehicle passes directly in front of a pedestrian who is on the zebra crossing; A2 - vehicle passes directly in front of a pedestrian who is on the sidewalk;

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Classification of vehicle-pedestrian encounters

B - vehicle passes immediately behind a pedestrian who is on the zebra crossing; C - vehicle slows down or stops before the crossing.

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Classification of vehicle-pedestrian encounters

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Site Safety Encounters A1 A2 B C Sum Warsaw POW (both lanes) without SF 7088 3,9% 16,2% 15,4% 64,5% 100% active SF 6418 4,6% 15,9% 14,5% 65,0% 100% Wrocław CEN without LL 11519 11,3% 41,7% 8.4% 38.6% 100% steady LL 3197 11.9% 33.8% 9.2% 45.1% 100% Wrocław SWO without LL 4425 15.1% 40.8% 7.2% 36.9% 100% active LL 3289 13.7% 33.9% 9.4% 43.0% 100%

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Yielding

Speed of vehicles and pedestrians

Mean speed profiles of vehicles over the distance of 30 m before the crossing were analysed Speed profiles for encounters A1 and C:

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Speed of vehicles and pedestrians

Speed profiles for encounters B and A2:

Generally lower speeds in Wrocław (higher flow) Levelite more effective than SignFlash

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Warsaw POW site Wrocław CEN site

* Speed measured 10 m from the zebra crossing

Effect of safety measures on approach speed

Situa- tion Time of day Without SF With SF Diffe- rence

• Sig. level

n V* [km/h] n V* [km/h] [km/h] A1 Day 197 45.0 237 41.4

• 3.6

0.01 Night 81 41.6 50 38.8

• 2.7

0.10 C Day 2647 15.0 3242 15.1

• 0.1

no Night 1909 15.5 917 15.7

• 0.2

0.05

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Situa- tion Time of day Without LL With LL Diffe- rence

• Sig. level

n V* [km/h] n V* [km/h] [km/h] A1 Day 1079 39.2 323 33.5

• 5.8

0.01 Night 222 41.8 56 32.7

• 9.0

0.01 C Day 3763 19.0 1161 16.9

• 2.1

0.01 Night 680 20.6 282 16.8

• 3.8

0.01

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Pedestrian speed distribution

Pedestrians tend to walk faster by ~2% (0.04 m/s) when vehicles are approaching

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0,70 0,75 0,80 0,85 0,90 0,95 1,00 1,05 1,10 1,15 1,20 1,25 1,30 1,35 1,40 1,45 1,50 1,55 1,60 1,65 1,70 1,75 1,80 1,85 1,90 1,95 2,00 2,05 2,10 2,15 2,20 2,25 2,30 Pedestrian velocity [m/s] Pedestrian count 0% 20% 40% 60% 80% 100% without vehicles with vehicles

• cum. dist. without vehicles
• cum. dist. with vehicles

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Survey of pedestrian risk perception

Video clips of vehicle-pedestrian encounters which seemed dangerous were extracted and used in a survey of pedestrian risk perception. Viewers were asked to rate the situations on a scale from 1 to 10 from the point of view of pedestrians

1 = very safe, no risk to pedestrian 10 = very dangerous, near accident

Viewers were students and traffic safety experts

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Encounter Risk Indicator

Formula calibrated by non-linear regression for encounters A1 and B:

Vv – vehicle speed at min. distance (m/s) S – minimum distance between vehicle and pedestrian (m) X – vehicle passes: 0 = in front of, 1 = behind a pedestrian Problem: the formula is not very sensitive to speed Calculated W show no positive effect of safety measures: SF and LL

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Distribution of calculated ERI

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Percentage of encounters with ERI W > 3.0: Warsaw POW = 15.0%, Wrocław CEN = 10.6%

Distributions of observed minimum distance

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Percentage of encounters with S ≤ 1.5 m:

Warsaw = 3.9%, Wrocław = 2.2%

Conclusions

Parameters which could be extracted from video: speed of pedestrians and vehicles, deceleration, minimum distance between users, PET value Classification of encounters is based on who passes first and on relative position on the zebra Levelite system considerably increases the percentage of yielding Levelite also causes a significant decrease of the approaching vehicle speed (at 10 m) – between 2.1 and 9.0 km/h

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Conclusions

User perception survey was conducted to rate the perceived danger of pedestrian-vehicle encounters The average risk scores correlate well with the following variables:

Minimum distance between vehicle and pedestrian Vehicle speed at minimum distance Type of encounter Maximum deceleration

Distribution of minimum distance can be used to identify the most safety-critical encounters

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