Signals Go for RTD : Buses With Strobes Will Trigger Green Lights on Ventura Boulevard

Bus drivers in part of the San Fernando Valley on Monday will get a green light on getting a green light.

As part of an experiment announced nearly two years ago, buses on 10 miles of Ventura Boulevard between Tarzana and Studio City will override the automatic traffic signals and be given green lights.

The driver will flip a switch to activate an infared strobe light mounted at the front of the bus. The strobe in turn will trigger switches at 49 intersections between Reseda Boulevard and Vineland Avenue.

If the light is green when the bus approaches, the strobe will extend the green signal for an additional 10 seconds. If it’s red, the strobe will trigger an early green.

Weighed for Wider Use

The optical sensors and the flashing lights have been installed on 76 Rapid Transit District buses to help traffic engineers decide whether such equipment should be considered for use citywide.

Transportation officials predict that the equipment, called signal preempters, will cut bus-travel times along Ventura Boulevard by 7%, save fuel, and reduce wear on buses, noise and air pollution.

All buses on the boulevard’s Line 150 and more than half of those on lines 424 and 525 have been equipped with the strobes, RTD officials said Friday.

They’ll Be Invisible

The pulsating, high-intensity lights will not be visible to motorists or pedestrians, the officials said. Sensors attached to traffic signal arms at intersections will respond to the strobe lights when buses get within about 500 feet of them, said James Okazaki, a city transportation engineer in charge of the experiment.

He said the buses’ strobes will not override pedestrian-operated signals to walk.

“We feel the effect on side streets will be minimal, but this is one of the things we’ll be measuring over the year,” he said. “Hopefully, the benefit on Ventura will more than offset the intermittent delays on the side streets.”

Relatively Light Traffic

He said cross traffic is relatively light along Ventura Boulevard because most of the cross streets dead-end nearby in the Santa Monica Mountains. Traffic engineers were reluctant to try the strobe system on a street with heavy cross traffic such as Wilshire Boulevard, he said.

Signal preempters have been used for years on emergency vehicles in many cities, including Burbank and Culver City. Los Angeles traffic planners have considered trying them on buses for seven years.

City and RTD officials said the Ventura Boulevard experiment had been scheduled to start 1 1/2 years ago, until problems with the strobes surfaced.

The flashers used in early tests burned out quickly. They operated as long as the bus was running, which meant that they kept flashing up to 16 hours a day.

Now drivers will flip a switch when their buses enter the experiment zone. A timer will turn off the strobes an hour later.

Officials said the flashers operate on a high frequency that cannot be duplicated by strobe lights available to private consumers--although at least one motorist has been observed flashing an electronic photo flash at one of the signal sensors.