PEDESTRIAN COLLISION WARNING DEMONSTRATION … · PEDESTRIAN COLLISION WARNING DEMONSTRATION...

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PEDESTRIAN COLLISION WARNING DEMONSTRATION PROJECT Approach and Findings Presented by Harry Saporta Kelley Klaver Pecheux, PhD 2015 APTA Bus and Paratransit Conference May 5, 2015

Transcript of PEDESTRIAN COLLISION WARNING DEMONSTRATION … · PEDESTRIAN COLLISION WARNING DEMONSTRATION...

PEDESTRIAN COLLISION

WARNING DEMONSTRATION

PROJECT

Approach and Findings

Presented by

Harry Saporta

Kelley Klaver Pecheux, PhD

2015 APTA Bus and Paratransit Conference May 5, 2015

Study team

Study objectives

Technologies assessed/tested

Test approach

Evaluation approach

Findings

Overview of Presentation

Study Team

Study was funded through an FTA Cooperative Agreement

Study was conducted by

TriMet

Applied Engineering Management Corporation (AEM)

Portland State University (PSU)

Study Objectives

Demonstrate the ability of various commercially-available turn warning

systems to provide timely warning to pedestrians/cyclists that a bus is

turning or pulling into/away from a bus stop.

Determine the effectiveness of the turn warning systems at intersections and

bus stops.

Determine the benefit-cost ratios associated with the turn warning systems.

Define the environmental parameters under which advance warning should

be provided to pedestrians/cyclists at intersections and at bus stops.

Assess the effectiveness of an innovative warning sign at one intersection.

Technologies Assessed/Tested

Three commercially-available turn warning systems:

Turn warning system 1

Spoken warning activated by rotation of steering wheel

Included two LED strobe lights on either side of the bus

Turn warning system 2

Spoken warning activated by rotation of steering wheel

Turn warning system 3

Beeping warning activated through use of the turn signal

Included directional LED headlights

“BUS” blank-out sign

Activated by a bus waiting to turn at an intersection (signal actuation)

Concept for the sign was developed by AEM

Test signs were designed and built by TriMet

Signs were installed by the City of Portland

A fourth commercially-available turn warning system was assessed but not tested

Spoken warning activated through use of the turn signal

Demonstration Test approach

Evaluation approach

Study Approach

Test Approach

45 buses equipped with systems (15 buses with each of the 3 turn warning

systems).

All test buses call came out of one maintenance facility.

Each day, test buses were placed on 5 pre-selected test routes:

Pre-determined number of each system on each route (ranged from 2-4,

generally 3, depending on the total number of buses on each route)

One test route was replaced halfway through the test due to public complaints.

“BUS” blank-out sign placed at both ends of one crosswalk at a busy

intersection in downtown Portland.

Test ran 7 months (March-September 2014).

Turn Warning System #1 -

“Pedestrians, Bus is Turning.”

Turn Warning System #2 - “Caution,

Bus is Turning.”

Turn Warning System #3 - Beeping

Warning

Directional LED Headlights

“BUS” Blank-Out Sign

Evaluation Approach

Bus operator surveys

Daily surveys conducted 3 times per week for 13

weeks

436 completed surveys

Comprehensive bus operator survey

208 completed surveys

Pedestrian surveys

Field intercept surveys administered at 5

intersections

454 completed surveys

Evaluation Approach (cont’d)

Bus operator focus groups

4 focus groups with 27 operators

Pedestrian focus groups

3 focus groups with 27 pedestrians

Analysis of pedestrian behaviors

80 hours of video data collected at 4 intersections

Interviews with TriMet staff

Cost-benefit analysis

Findings

Overview of Findings

There were a number of common themes that emerged

throughout the study.

There was a (somewhat wide) range of feedback

regarding perceptions, acceptance, and

recommendations for improving the technologies

representing mixed findings.

Benefit-cost analysis

Warning volume – finding an appropriate volume

level for the warnings

Sensitivity of warning activation – finding the right

sensitivity setting for warning activation

Warning - selecting the right warning type/content

Application of the warnings – determining when

and where the warnings should activate

Common Themes

Warning Volume

Getting the volume of the warnings right was an issue throughout the

demonstration test.

Early complaints from operators and residents led to volume adjustments.

Noise complaints declined, but a growing number of operators reported in the

daily surveys that the volumes had become too low to be effective.

Overall lack of consensus in feedback:

Operator responses showed that the “too loud” margin was significantly greater for systems with

the spoken warning than for the system with the beeping sound.

A majority of pedestrians surveyed did not find the warnings to be intrusive to the environment.

Of those that did, more found the spoken warnings to be intrusive than the beeping warning.

Participants in the pedestrian focus reported that the volumes of the spoken messages were

acceptable once they were adjusted, but that the beeping warning was still too loud.

Repetition and/or frequency of warnings may also play a role.

Sensitivity of Warning Activation

Specific to the systems activated by rotating the steering wheel.

Activation angles for both systems were initially set to provide early warnings.

Initial turn angles produced false activations of the warnings in certain situations.

Mitigated somewhat via system adjustments to one of the systems, which was evidenced by a downward trend in the reporting of false activations in the daily operator survey.

A majority of operators still indicated in the comprehensive survey that the systems activated too early and/or in roadway curves.

Operator focus groups confirmed that the problems were mitigated somewhat via system adjustments but continued in some cases.

Speed threshold may also play a role.

Warning Type/Content

Operators were most divided over the beeping warning:

Some preferred it over the spoken warnings because it is “universal” and/or more effective at getting people’s attention.

Others did not like it because it was too loud, harsh, irritating, and potentially distracting.

Strong consensus that “caution” is better than “pedestrians.”

In addition to warnings used in the demonstration test, a variety of auditory warnings were presented to and discussed with focus group participants:

Shorter, concise warnings were generally preferred over longer, more detailed warnings.

“Caution, bus is turning” was rated above all others and was favored by most.

A recommendation from both operators and pedestrians:

Easily-recognized and unique to TriMet buses, as well as “friendly.”

Warning that incorporates both a spoken warning and a sound/tone.

Application of the Warnings

Overwhelming agreement by operators that the turn warnings are important, if not more

important, at bus stops than at intersections (pedestrians tended to agree).

Generally (slightly) more necessary during right turns (as opposed to left turns) and when pulling

into a stop (as opposed to pulling away from a stop).

Two recurring issues suggest that it may be prudent to consider selective versus ubiquitous

application of the turn warnings:

Early complaints - giving more thought to where the warnings should activate (and at what times of the day) could

help to avoid these types of complaints.

Long-term efficacy - bus operators and pedestrians believed that the warnings would eventually blend into the

background noise and/or be tuned out.

Both operators and pedestrians strongly recommended that the volumes vary by location and/or

time of day or that the volumes adjust automatically relative to the environment.

Alternatively (or additionally), participants recommended that warnings activate only on

“trouble” routes/locations and/or at locations with history of conflicts.

Flip side – issue of liability if a pedestrian is struck at a location or time of the day when the

warnings are inactive.

Important to involve the community when selecting locations.

Wide Range/Mixed Feedback Regarding:

Perceptions of technology effectiveness

Acceptance of the technologies

Recommendations for improving the

technologies

Perceptions of Technology Effectiveness

Overall, bus operators were generally less favorably impressed with the effectiveness of

the turn warning systems than the general public:

As is, the turn warning systems are only somewhat effective at improving safety (system and

pedestrian related).

Improvements, programming/customization, and some added operator control features could

make the systems more effective.

Systems not the “be-all-end-all” to reducing pedestrian-bus collisions (operator and pedestrian

accountability).

The warnings are as or more effective at service stops than at intersections, with pulling into a

stop being the more critical movement.

The turn warning systems are less effective with cyclists than with pedestrians.

LED cornering headlights highly effective at improving visibility in the direction of the

turn.

A fair majority of pedestrian respondents felt that the systems were effective at both

alerting pedestrians and improving pedestrian safety.

Just over half of pedestrian respondents found the BUS blank-out sign to be effective at

alerting pedestrians that a bus is turning and at improving pedestrian safety.

Acceptance of Technologies

Operators:

Nearly half of operators surveyed agreed that the potential safety benefits outweighed the drawbacks of the warning systems.

However, overall, only about one third agreed with the prospect of wider deployment, while nearly half disagreed.

General sentiment from focus groups regarding further deployment could be described as ranging from apathetic to skeptical – most seemed to have adapted to the presence of the warnings, but did not strongly support nor completely reject the idea of their continued or expanded use.

Pedestrians:

A majority of pedestrians surveyed did not find the warnings to be intrusive to the environment.

Further, a majority agreed that more systems should be installed.

A small group agreed that the potential benefits outweighed the associated drawbacks, but disagreed with the idea of further deployment. Could be associated with costs – money better spent elsewhere.

Recommendations for Improving

Technologies

“Tweak” the systems and “get the bugs out.”

Tie the system to the turn signal (as opposed to the steering wheel).

Select a lower speed threshold for warning activation.

Integrate systems with GPS/AVL system to be more programmable.

Operator control

Most operators agreed that total operator control over the system was not a good

idea.

Some operators advocated for some level of control (e.g., volume and when

warning could be sounded).

Others strongly recommended that operators be given no control over the system.

If more programmable, would reduce/eliminate need for any operator control.

Imputed benefits

Cost-benefit analysis

Costs and Benefits

Imputed Benefits Framework

Bus-pedestrian collisions resulting in injuries or fatalities are rare events.

2010 National Transit Database – 27 fatalities and 283 injuries requiring transport in association with 1.6 billion

miles of revenue service.

This translates to about 1.7 fatalities and 17.7 injuries per 100 million revenue service miles.

TriMet’s entire bus system logs approximately 20 million revenue service miles per year.

A research design predicated on documenting changes in fatalities and injuries on six routes over a 7-month

period would likely find no “treatment effect” attributable to the turn warning systems.

Drew on safety pyramid concept – Bus-pedestrian close-calls more common than actual

collisions. Given a defined hierarchy of safety risks and outcomes, it is possible to

impute the expected incidence of pedestrian fatalities and injuries in relation to the

frequency of close-calls.

Employed relative frequency data specific to close-calls

and collisions involving buses and pedestrians (national and

transit property data) to operationalize the safety

pyramid for this study.

Imputed Benefits

National data – 2010 NTD

Fatalities and injuries requiring transport

Transit property data – TriMet

Safety information system (Dec ’10-Oct ‘14)

Bus-pedestrian collisions, injuries (requiring transport minor,

none)

Close-calls

Pedestrian close-call button (since 2013) – not well

documented (under reported) by operators

Data from 2012 survey of risk perceptions – frequency of

total close calls

Evasive action/hard stop events due to pedestrians

Daily operator surveys – reported reduction in close calls

due to turn warning systems

1.0

10.5

30.0

37,723

Incident Types Close-Calls per

Incident

Annual Avoided

Incidents

Years to

Realize

Fatality 37,723 0.037 27

Injury (transport) 3,593 0.393 2.5

Minor or No Injury 1,257 1.124 11 months

Cost-Benefit Framework

Guidance from

OMB Circular A-94

Information on discounting

Treatment of uncertainty

Treatment of the Economic Value of a Statistical Life in

Departmental Analysis, U.S. DOT

Monetary valuation information

12-year cost-benefit analysis timeframe

7% discount rate

Cost Analysis

Accounts for uncertainty by employing a range of values for each key parameter:

Avoided incidents

Valuation of fatalities and injuries

Installation and maintenance costs

Three scenarios

Baseline - employs the baseline cost and benefit component values

Maximum scenario – employs the combination of cost and benefit values that yield the largest achievable net benefit outcome

Minimum scenario – employs component values that produce the smallest net benefit

Results

Cost-Benefit Components Baseline Maximum Minimum

A. Present Value Total Benefits $3,047,131 $7,055,243 $693,591

B. Present Value Total Costs $108,669 $66,205 $151,134

C. Net Present Value (A-B) $2,938,462 $6,989,038 $561,807

D. Ratio of Benefits to Costs (A/B) 28.0:1 106.6:1 4.6:1

E. Internal Rate of Return 34.5% 51.4% 16.5%

Results are for the 45 test buses on the 6 test routes.

Potential elevated relative risk exposure:

While representative of TriMet’s overall network, the test routes are somewhat longer, have

more turns, and serve more passengers than average.

Systems were installed on new buses assigned to base service runs.

Monetary benefits from avoided fatalities/injuries due to the turn warning systems

include social monetary benefits as well as avoided financial liabilities realized by

a transit agency.

Questions?

TriMet Harry Saporta

Safety and Security Executive

[email protected]

(503) 962-4909

AEM Corporation

Kelley Klaver Pecheux

Associate Director of Transportation

[email protected]

(703) 464-7030 ext 8117

Federal Transit Administration

Roy Wei-Shun Chen

Transportation Engineer

[email protected]

(202) 366-0462