Experience with bus-based pedestrian warning systems 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 (15 buses with each type of system).
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.
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 cost information excerpted from the source report are shown below. These costs represent a hypothetical purchase order from a public transit agency in December 2014. During data collection manufacturers were asked to provide representative unit costs for a bulk retro-fit of 50 buses.
|Features||Unit Cost of System A||Unit Cost of System B|
|Speed sensing technology||Included||Included|
|Ambient volume adjustment||Included||Included|
|Installation and training||Included||$505|
|Object detection||Included (less sensors)||Not available|
|Warranty||2 yr (Included)||1 yr (Included)|
* To support geo-fencing, RF receivers must be installed in each area where geo-fencing is required. This cost was not included in the estimated for System A. The unit cost for each RF receiver was estimated at $1,000.
Prepared by Applied Engineering Management Corporation for the FTA
Purchase and installation of a transit vehicle turn pedestrian warning system on 45 buses: $58,500 to $97,200.