We talk a lot about smart work zones here so we take it for granted that everyone knows what we mean when we use that term. But apparently many do not. Several states are now requiring smart work zones on projects, but their specifications only show the number of message signs required. The messages on those signs are then changed manually as needed by the TMC. So the only thing that is “smart” about their work zones is the modem in the message signs.
There is so much about this that bothers me! A contractor is being paid to supply a full system, yet is only supplying signs. This cheats taxpayers and road users and results in a far less safe work zone. It will also be more difficult to convince decision makers to include work zone ITS elements in future projects.
The signs are updated manually from the traffic management center. Most TMCs are not staffed 24/7 so the “system” only works when someone is there to operate it. If the DOT chooses to staff the TMC for this purpose they are paying far more than it would cost to automate the process as was originally intended.
They are using existing ITS elements to monitor traffic through the work zone. Most DOTs say that about 20% of permanent loops, sensors and cameras are off line or out of service at any given time. Even on a very well instrumented stretch of roadway, this would leave unacceptable gaps in coverage for most work zones. To react quickly to slowing or stopped traffic you need sensors spaced a half mile to at most one mile apart. At freeway speeds you will then learn of slowing less than a minute after it begins.
And, most important of all, humans cannot react to events and change the signs as quickly as software does. That leads to more secondary crashes, slower EMS response, and longer delays for the folks driving through these work zones.
These states need to tighten up their specifications immediately. There are many good examples of work zone ITS specs available now. Gerald Ullman of the Texas Transportation Institute recently developed a great one for TxDOT. Scott McCanna at Oregon DOT also has a good one. But whatever states choose to use as a specification it must include either specific numbers of sensors, or very clear performance measures regarding event detection and response.
In the meantime, as the torchbearers for work zone ITS, we need to explain what devices and software a work zone must include to be called “smart”. If we do not, we will have only ourselves to blame for the dumb results.