This project evaluated the benefits and costs of transit vehicle turn warning systems designed to improve safety for pedestrians in Portland. As part of a cooperative agreement with the Federal Transit Administration (FTA) the Tri-County Metropolitan Transportation District of Oregon (TriMet) equipped 45 buses with three types of commercially available auditory warning systems, and installed an infrastructure-based warning system as a prototype at a crosswalk. The bus-based system used auditory messages and LED directional lighting on the forward side of each bus to improve driver visibility and alert pedestrians at intersections on five bus routes. The system was activated automatically when bus speed profiles and steering components met pre-defined thresholds on each bus route. The infrastructure-based system used pedestrian detection and intersection signal control systems to activate BUS blank-out signs. As a prototype, these warning signs were mounted on pedestrian signal heads at the intersection of SW 5th Avenue and W Burnside Street. When a pedestrian was detected and a bus was approaching from the turn lane, the word "BUS" was displayed on the blank-out signs as a warning. Evaluation data were collected over a seven month period from March to September 2014. Bus drivers and pedestrians were surveyed, and focus groups were conducted to assess perceptions and overall satisfaction with the technologies deployed. Additional research was conducted to assess impacts on pedestrian behavior. Data were collected from in-vehicle sensors and cameras.
The bus-based systems used auditory messages and LED directional lighting on the forward side of each bus to improve driver visibility and alert pedestrians at intersections on five bus routes. The system was activated automatically when bus speed profiles and steering, brake, and turn signal system components met pre-defined thresholds on each bus route.
- System A was a commercially available turn warning system that provided an external auditory warning to pedestrians and other road users when a bus made a left or right turn. Using sensors to monitor the movement of the pitman arm steering linkage the system automatically played the auditory warning when the bus steering wheel turned the linkage activated an electronic sensor. To prevent warnings from being broadcast during a normal lane changes or other turns of the steering wheel the system incorporated a maximum speed threshold feature. The outside speaker system was equipped with an automated volume adjustment feature to compensate for ambient noise around the bus. Strobe lights on the exterior of the bus flashed simultaneously with auditory warnings. An optional geo-fencing feature was proposed to enable agencies to disable the auditory warning in specific areas.
- System B was a commercially available turn warning system that provided an external auditory warning to pedestrians and other road users when buses made left or right turns. System B differed from System A only in the way in which the auditory warnings were activated. System B used an optical sensor and a sticker having a checkerboard pattern affixed to the column of the steering that enable the system to be activated.
- System C was a commercially available turn warning system designed primarily to improve driver visibility using a directional LED headlight system. These lights, housed with the main headlights, were illuminated when turn signals were activated to provide an additional 35-degrees of visibility on side of the existing headlights beam. The auditory turn warning system used a beeping noise and was activated in tandem with turn signals when the driver’s foot was released from the brake pedal.
The infrastructure-based system used pedestrian detection and intersection signal control systems to activate BUS blank-out signs. As a prototype, these warning signs were mounted on pedestrian signal heads at the intersection of SW 5th Avenue and W Burnside Street. When a pedestrian was detected and a bus was approaching from the turn lane, LEDs were activated on the blank-out signs and the word "BUS" was displayed as a warning.
- Bus Operator Surveys: Bus operators were surveyed three days per week over a three month period from April 2014 through June 2014. In addition, a final comprehensive survey was conducted in September 2014 at the end of the demonstration period. Overall, 436 daily surveys and 208 final surveys were collected and analyzed.
- Bus Operator Focus Groups: A total of 27 bus operators participated in four 90 minute focus group sessions.
- Pedestrian Field Intercept Surveys: Three months after operations were initiated pedestrians were surveyed at five different intersections including the intersection with the BUS blank-out signs.
- Pedestrian Focus Groups: A total of 27 pedestrians participated in three 90 minute focus group sessions.
- Video Data Collection: Cameras were installed at intersections to record pedestrian and cyclist activity. Twenty (20) hours of data were collected to assess daytime and nighttime conditions at four intersections.
Overall, survey and focus group findings indicated that bus operators were generally less favorably impressed with the effectiveness of the system than the general public.
Bus-based warning systems - From the daily surveys, less than half of the bus operators thought the systems were effective at alerting pedestrians at intersections and bus stops, and less than one-third thought the systems were effective at reducing close-calls. Operators noted that pedestrians often were not paying attention or were engaged with electronic devices.
Infrastructure-based warning systems -More than half of respondents reported that the BUS blank-out signs were effective at alerting pedestrians and improving safety. Twenty-three (23) percent reported that the signs helped them avoid a collision with a bus.
Prepared by Applied Engineering Management Corporation for the FTA
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