Tuesday, December 18, 2007

Caltrans response to questions about bicycle detection

I recently received a letter from Caltrans in response to questions that I sent them on October 28 about bicycle detection. I am concerned that although they say they will be installing bicycle detection at new and modified traffic actuated signals, their only options are Type D loops and video detection. They totally ignore my October 16 presentation to their Electrical Systems Branch on detecting bicycles with loops that, among other things, recommended larger loops and the use of bicycle detector symbols. Furthermore, they plan on doing no more development work on in-pavement detection (loops) and to concentrate on video detection. That means that any progress on improving bicycle detection at existing signals with inductive loops is years, if not decades in the future. Finally, they are concentrating on detection methods that differentiate between motor vehicles and bicycles rather than on detecting bicycles in the first place. They are not taking first things first.

The letter says that they will be adding a Discussion Item to the January 2008 CTCDC meeting agenda. I think that we should have some representation at that meeting to try to change Caltrans' direction and to get them to do some development work on inductive loops. I will be contacting the secretary of the CTCDC about giving a short version of the presentation that I made to the Electrical Systems Branch, focusing on my recommendations to Caltrans.


Bob Shanteau
Consulting Traffic Engineer

Robert M Shanteau, PhD, PE
13 Primrose Cir
Seaside, CA 93955-4133
Voice: (831) 394-9420
FAX: (831) 394-6045


bikesgonewild said...

...fritz, can you better define this in basic terms...concept parameters, locales...just trying to get a better take on it & i figured you are probably well versed...

Fritz said...

Bob's the engineer :-)

Quickly, though, Bob made recommended improvements to Caltrans standards for inductive loop detectors. Caltrans ignored/rejected those recommendations in favor of pushing for new technology.

Unfortunately, the video detectors are a lot more expensive than the old loop detectors. Bob can comment more, but I think the concern is that local governments will forgo making any changes at all if their only option is something that costs an order of magnitude (or more) than their existing installations.

Bob, can you clarify?

bikesgonewild said...

...i wondered if this would ultimately be a mandatory statewide setup or if individual cities & towns could by-pass it on their own...
...hopefully not...

Bob Shanteau said...

Earlier this year the California legislature passed and the governor signed AB 1581, which says in part:

Upon the first placement of a traffic-actuated signal or replacement of the loop detector of a traffic-actuated signal, the signal would have to be installed and maintained, to the extent feasible and in conformance with professional engineering practices, so as to detect lawful bicycle or motorcycle traffic on the roadway. Cities and counties would not be required to comply with those requirements until the Department of Transportation has established uniform standards, specifications, and guidelines for the detection of bicycles and motorcycles by traffic-actuated signals and related signal timing.

Almost all traffic actuated signals in California, indeed all over the world, use inductive loops to detect vehicles. Inductive loops are notorious for not detecting bicycles. And if you are not detected, then you don't get a green light.

If you want to know more about inductive loops and bicycle detection, see my presentation to Caltrans:


Let me know if you need more information.