Alex Goldmark is the senior producer of New Tech City, a storytelling show about how technology is changing society. Subscribe here to get New Tech City shows delivered right to your devices. Follow him on Twitter @alexgoldmark.
This Traffic Light Senses Bikes, Promotes Road Harmony
Wednesday, January 04, 2012 - 03:16 PM
Cyclists have a new friend out there on the roads: microwaves. And the city of Pleasanton, California, is one of the first cities in the country to roll out this high-tech solution to help cars and bikes share the road.
The Intersector is a so-called intelligent traffic signal. It detects when bikes are coming and changes the timing of the green light to accommodate the slower-moving -- and more vulnerable -- cyclist. For instance, Pleasanton estimates that a for a given intersection a car needs four seconds to clear the intersection after a red light. So the cars get four seconds of green time. A bike, though, takes 14 seconds. That could be ten dangerous seconds for the cyclist as three lanes of cars prepare to dash across his or her path.
So Pleasanton has implemented the Intersector bicycle detection system in seven city traffic signals with plans to upgrade all others as replacement and repair is warranted. The city had used coils in the pavement and digital cameras to detect vehicles approaching traffic signals, but bikes are too light to set off the in-pavement coils, and automated cameras can't tell the difference between cars and bikes.
The Intersector uses microwaves to measure the size and speed of oncoming vehicles to determine which are cars and which are bikes. The signal adds on additional time to allow bikes to pass through safely. And when bicycles are stopped at the red light, they are recognized, and given 14 seconds of green light time to pass -- as compared to four seconds when only cars are waiting.
“To the City of Pleasanton, this is the best of both worlds -- providing additional green timing and green extension timing only when bicycles are present, while utilizing more efficient traffic signal timing more appropriate for vehicle traffic the remaining times,” said Joshua Pack, Pleasanton's senior transportation engineer in a statement.
The Intersector initiative was awarded ITS America’s Smart Solution Spotlight award for using innovative technology. "The ‘Intersector’ allows cyclists and vehicles to co-exist safely on the road and ITS America applauds the City of Pleasanton for working to become more bike friendly,” said ITS America President and CEO Scott Belcher.
The group said the "radar-style" device costs between $4,000-$5,000 per sensor, and can either work in conjunction with existing vehicle detection technology or can be installed as a comprehensive detection device.
Technology website GovTech notes that the Intersector has some drawbacks: fewer lanes and traffic actions can be monitored at once than by cameras.