The Express Traffic Lane (It’s Not the Computer, It’s How You Use It)

Friday, September 24th, 2010 by Max Baron

Less than a week ago, a section of the diamond lane in California’s southbound Interstate 680 freeway became sensor-controlled or camera-computerized. A diamond lane, for those of us not familiar with the term, is an express traffic lane allowed only to high-occupancy automobiles or types of vehicles that use environmentally friendly fuels or less gasoline.

Also known as the carpool lane, the diamond lane is usually marked by white rhombuses (diamonds) painted on the asphalt to warn solo drivers that they are not allowed to use it. The diamond lane provides fast free commuting for carpoolers, motorcyclists and diamond lane sticker owners. Solo drivers must use the remaining lanes that are usually slower during periods of peak traffic. These single drivers however, are now allowed to use a section of the diamond lane in California’s southbound Interstate 680 freeway — but they have to pay for it.

The camera-computerized or sensor-activated system introduced just a few days ago doesn’t make sense considering the state-of-art of available technology.

Here is how the complex system works. An automobile carrying only its driver must have a FasTrak transponder allowing a California-designated road authority to charge a fee for using this newly created toll-diamond lane. Mounted on a car’s windshield, the FasTrak transponder uses RFID technology to read the data required to subtract the passage fee from the car owner’s prepaid debit account. The fee reflects the traffic level and is changed according to the time of day. The fee is displayed on pole-mounted digital displays.

To avoid being charged if there are also passengers in the automobile, a FasTrak transponder owner must remove the vehicle’s transponder from the car’s windshield. Caught by traffic enforcement (California Highway Patrol) a solo driver without a FasTrak transponder is fined for using the diamond lane without paying for the privilege. Other schemes implemented for instance at a toll plaza, will trigger a camera to take a photo of the delinquent vehicle and its license plate following which a violation notice will be sent to the registered owner of the vehicle.

Considering the complexity of the system from the viewpoint of existing digital cameras, embedded computers, cellular telephony and the presence of police enforcement on the freeway, one can wonder about the necessity of FasTrak devices or police involvement. 

If we are to follow descriptions found on publications such as San Jose’s Mercury daily newspaper (reference) and the freeway’s information brochure (reference), the system seems to be unnecessarily disconnected: an RFID tag is used to pay for solo driving, but police has to check if a vehicle without a transponder is occupied by just the driver or by additional people. If a FasTrak-less driver is detected police must stop the delinquent car and write a ticket. Based on the description, it may seem that the cameras or sensors implemented are unable to differentiate among illegal solo drivers vs. multiple passenger cars. If true, these cameras or sensors are using technology that was state of the art in the 90’s.  They only seem to be able to detect a large object well-enough to report to police the number of vehicles using the lane without transponders, leaving the rest to law enforcement.

Today’s embedded computers equipped with simple cameras can read numbers and words. FasTrak transponders should not be required. Existing systems can identify human shapes and features in cars well enough to differentiate among multiple vs. solo drivers and with adequate software and illumination, they can continue to function correctly despite most adverse weather changes or light conditions. The word “CARPOOL” written by the driver of a multiple-person car can be displayed for the computer to read to ensure that the system will not charge for the use of the toll-lane. The license plate of the solo driver automobile can be linked in a data base to a debit account or to the name and address of the owner.

We estimate the price of a pole-mounted low-power system of this kind including wireless communication at a pessimistic $9,800 as follows: a ruggedized camera– $1,500; a video road image recognition engine plus software such as designed by Renesas for automobiles — $2,000 including software (reference); a controlling embedded computer including a real-time OS — $900; a wireless communication block — $600; components for remote testing, upgrades and servicing–$1,000; battery and power supply– $1,000; solar panels if required–$800; enclosure–$2,000.

In a modern system there would be no fines—just charges made to driver bank accounts if so elected–or monthly statements to be paid along with electrical, gas, and other services for which monthly payments have found acceptance. But, have we been told everything? Do we really know what types of systems are looking today at the traffic on freeway 680’s toll-enabled express lane? This may be just step one.

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3 Responses to “The Express Traffic Lane (It’s Not the Computer, It’s How You Use It)”

  1. Dan says:

    Not trying to be smug here…

    Sounds like you’ve got it all figured out. Why not start a business around your idea & sell the system to the state?

    Might as well get rich off of your idea.

    • Max Baron says:

      The acceptance of technology is influenced by business aspects. There are business reasons why a fully computerized solution will not be easily accepted. It would prevent fines, remove the need of FasTrak stationary and mobile devices, and put money back into drivers’ personal bank accounts. The cost to drivers would be lower, more predictable and not subject to human error, but there will be loss of revenue and jobs.

      The short article however was intended to address the technical context. If you are interested and have access to the Microprocessor Report, read my 2007 article “Front Seat Driver” describing the Renesas SH-Navi2V chip’s image recognition capabilities (no, it was not designed on Pandora). The chip’s 64-core parallel semi-hardwired engine could execute image-recognition algorithms at 38.4GOPS. The engine could recognize cars, lane boundaries and read speed-limits and temporary road signs posted on freeways. Concurrent tasks were supported by an SH-4A core and additional dedicated accelerators. The chip was priced at about $150 in single-unit quantities (¥15, 000).

  2. Ed Stark says:

    So if i am understanding this correctly, if i have a passenger and do not remove the transponder then i am charged the prevailing toll. is this correct?

    On the flip side, if i am a single occupant how does the system know except visually by a police officer?

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