GPS Tracking ROI

Road pricing: Your bill is on its way

By James Ruppert

23 May 2006

Pay as you drive has become the Department of Transport’s new big idea. The new Transport Secretary, Douglas Alexander, has promised more cash will be available for congestion charging schemes as he pledged to get road pricing to work. He promised to make £200m available from 2008 to help councils with a view to setting up a pilot charging scheme within five years. This would be followed by a national scheme.

The anticipated scheme would use the Global Positioning System to fix the precise location of all vehicles, with cost anticipated to range from 2p a mile for rural stretches of road up to £1.30 for the busiest. Such a scheme could replace fuel and road tax. In 2004 the Department for Transport published a feasibility study on road pricing, claiming it would be “revenue-neutral”, which means that the overall level of motor taxation will remain the same. Now that’s good news isn’t it?.. Read James’ Full report, it’s interesting:

Now I slugged this post as the “Dirty Little Secret” and James has come across it right away in his report. The car’s odometer says he drove 111 km and the commercial GPS tracking system claims he drove only 98.5 km. There’s about a 12% variance … in just two partial days of driving. I don’t know about you, but if the government put ammeter on my vehicle and wanted to charge me more than a pound per kilometer … dollars per mile … someone better know which device is accurate … the odometer or the GPS tracker. Even though I am many miles away from Belfast and haven’t had the opportunity to test either the odometer or the GPS unit I can give you an expert opinion as to which one is reporting the accurate mileage. Neither one. This is a significant problem that no one seems to be working on a solution for, in spite of scheme after scheme being introduced to put PAYD — Pay As You Drive – in place.

In the US, the most regulated country in the world it often seems, there is no Federal law which requires proven accuracy for odometers. Most auto manufacturers, when pressed, will state that %% or even 10% error is within “manufacturing standards”. Not too surprisingly, since warrantees, leasing contracts and other contracts involving mileage depend on the vehicle miles traveled, the great majority of odometers seem to register “high” … rolling up more miles than the owner actually gets from the vehicle. I’ve also been involved in court case research here in the US where even the mileposts alongside highways have been “proven” in court cases to be unacceptable as proof of miles covered. Doesn’t sound to me like something you can legally bases charges to the public upon.

GPS units, in most cases, are much worse. The average GPS tracking unit will seriously under report mileage due to simple geometry. The unit calculates a GPS position … a fix … every so many seconds. The device then calculates distance traveled by plotting a straight line between those two points. But if the vehicle was perhaps going around a curve on a highway the actual distance was along the outside of the curve. The points and straight lines between them represent chords of the curve. If you didn’t pay attention in Mrs. Mascolo’s geometry class, review a geometry textbook. Those chords, added together, do not add up at all to the actual distance traveled. The farther apart the unit calculates position, the worse the induced errors become. The best GPS units on the market (the ones I sell, naturally), calculate the position every second and have an accuracy that approaches ½ a percent. Some commercial units only give a fix every 2 minutes or 5 minutes. Want to have your bank account controlled by something with that much built in error?

Bottom line? PAYD schemes may be good or may be not so good, but if they are to be implemented they need something better than the present common mileage measuring technology. With what we have commonly available, we just don’t have the proper data to measure the mileage … and you can’t manage what you can’t measure.