Four years after one of its bus drivers fatally collided with two women in a downtown Portland crosswalk, TriMet is testing a few devices that use sounds and lights to show when a bus is turning.
One uses flashing LED strobe lights and the announcement “pedestrians, bus is turning,” repeated twice by the voice of a slightly alarmed woman. Another uses only a softer audio warning: “caution, bus is turning” three times. They started operating on 45 buses on five of TriMet’s frequent service lines on Monday: the 4, 8, 15, 33 and 75.
The folks at Oregon Public Broadcasting uploaded each file to Soundcloud for easy testing over the web. Here’s the first one, which isn’t being tested with LED accompaniment:
And you can hear the second sound at the start of this OPB radio spot:
In addition to the audio devices, TriMet is testing a third light-only device on some buses: one that uses the bus’s speed and steering wheel angle to automatically turn on “additional super bright LED lights inside the headlight pointed in the direction of travel.”
There’s also a static bus warning sign on Southwest 5th Avenue at Burnside: the word “BUS,” above the walk/don’t walk signal, which lights up when a bus is approaching.
Bus turns, especially left turns, are often difficult for other road users to anticipate, because the vehicles don’t begin to swing quickly around until partway through their turns. That’s why the regional transit agency’s new devices are triggered, in whole or in part, by the angle of the steering wheel.
Because the devices are calibrated to capture intersection turns only, it’s unlikely that the buses will make their announcements during lane changes — pulling across a bike lane for a stop, for example.
An earlier test of similar systems, in 2011, failed because the systems were either too sensitive to the turning wheels or not sensitive enough. You can read about the whole program in more detail on TriMet’s website.