When my home state of Illinois originally rolled out its electronic tolling program, I-PASS, the toll authority, said that the transponders in the vehicles would never be used to track your location, only to collect tolls as you pass through the tolling gateways. This being state government, no-one believed them, and it appears that that day is upon us.
During the last year or so, Illinois has virtually forced its residents to purchase the electronic tolling transponders by doubling the tolls for users paying with cash. For me, that would mean going from $0.40×4 tolls ($1.60 for about a 20-mile commute) to $0.80×4 tolls ($3.20 per day, $16/week, $64/month, $768/year). I can’t afford to pay the extra $384 per year, so I had to purchase the $15 transponder, along with just about every other commuter in Chicago.
Once everyone had the I-PASS transponder, all toll plazas in the Chicago area went under construction to have “open-road tolling”. This basically means that you don’t have to slow down to pay your toll, they get your transponder number as you go underneath the sensor array.
Case in point, there is a toll booth for motorists entering or exiting I-355 to/from I-55. Here is a satellite map of this toll plaza. You can plainly see the open-road tolling lanes on the inside, and the toll booths on the outside, both for motorists without I-PASS, and people with trailers, etc. that have special tolls they need to pay.
9 blocks north of this toll plaza is the 75th street overpass, about a half mile away. What you can’t see on the satellite map is that there are a second set of sensors hidden between the girders underneath this bridge. I wouldn’t have noticed them, if it weren’t for the spotlights that enable a set of cameras to record the rear license plate of cars as they go through.
It does seem a bit odd when you approach the bridge at night. Most bridges are lit from a few fluorescent rods at night, while this one is incredibly bright. It isn’t until you pass under the bridge that you notice that all of the lights are facing with traffic, pointing at the back of the cars as they go through the overpass. It’s blatantly obvious coming the other way, as the lights are shining towards you. There are no lights or sensors on the southbound side.
In the old days, the older I-PASS transponders used to beep when they were read. I think this caught the Illinois DOT by surprise, because some people still have them, and her is now a sign next to the highway, reading “I-PASS Users: ignore beep, you were not charged.”
So what purpose, exactly, would an installation like this serve, if not to catch speeders? Can we expect this on every overpass? Setting up a system like this only seems to serve two purposes, as I can see:
Traffic/Congestion Monitoring
I’m sure this will be IDOT’s excuse for installing more of these. This is completely bogus, since there are already thousands of sensors buried in the roadways that can accurately record traffic conditions. Here is a great implementation of the usage of these sensors, which update every few seconds. Unfortunately for IDOT, this doesn’t give you any personally-identifiable information about the motorists.
Speed Traps
By taking the distance between the sensors (let’s say a half-mile) and taking the posted speed limit (let’s say 60 miles per hour), IDOT knows that it should take you exactly 30 seconds to get from sensor to sensor. If you got there in 25 seconds, they can figure out (via basic math) that you were doing 72 miles per hour.
Now I’m not saying that catching speeders is wrong. The speed limit, however wrong that may be, is still the law. The debate as to safety vs. speed limits could go on forever, and it’s widely known that there are much less speed-related problems on the interstate than on the streets.
Anyway, my problem is with forcing people into the system by jacking up tolls, knowing that you’re going to turn it into a speeding-ticket revenue machine in the near future, and all the while saying that you’re not going to use it for that exact purpose.
In addition, the half mile laid out on I-355 is prone to errors. People stopping at the booth would be able to accelerate all the way to the 75th street overpass, exceeding the speed limit, since their average speed would stay below the limit.In effect, starting from 5 mph at the toll booth enables them to basically ‘earn’ the right to speed later by going below the limit while leaving the toll plaza.
Also, the distance between the sensors is prone to errors. Just one second of delay with either sensor reading (or if one sensor is off by one second compared with the other) would make a computing error of 2.4 miles per hour. (if we used the example data above)
In additon, you’re allowed to have multiple cars listed for each transponder. If the transponder doesn’t register, the camera looks up your plate # and bills your account. No account, and you get a ticket. So what’s stopping someone from registering a second car on their transponder, then taking the car, blasting through the first booth, and throwing the transponder under the seat for the second? The first booth sees the transponder, the second sees the plate#. Pretty sure the camera isn’t being used for every car, just the ones that don’t register when they drive through…
All in all, these sensors seem to be in the testing phase for catching speeders. Due to the problems I list above, anticipate trying to explain yourself when errors occur, and still being fined because you couldn’t explain it in simple-enough terms to your state’s EnforceBot.
Also, if you don’t live in Illinois, don’t laugh. It’ll come to you soon enough.
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