Why Aren’t Queue Warning Systems Used On Every Project?

Those of us that have been in the work zone ITS industry for several years understand that agencies don’t change quickly. New technology must be tested and evaluated before it is used on a more regular basis. We get that. But we are now at the point where queue warning systems should be included on every project where frequent and dynamic queuing is expected.

WZcrashesStudies by the Texas Transportation Institute have shown a reduction in rear end crashes of as much as 45%. Crash severity is reduced as well. Other states including Illinois have also seen a dramatic decrease in crash frequency and severity.

These systems are inexpensive and the benefits are substantial. Avoid just one lawsuit by using queue warning and that savings will more than pay for the cost of the system. So it does not matter how long the project lasts. Projects lasting only a few days could deploy a system for something like $700 per day.Projects months long would pay something like $10,000 per month. Those prices include the sensors, message signs, communications costs, design, set-up, etc.

One law suit will cost tens if not hundreds of thousands of dollars.  It really is that simple. And that doesn’t take into account all of the other benefits. Fewer crashes mean the project is completed faster. Motorists are happier with the DOT because they aren’t experiencing long delays. And you will have the data to meet the Federal Work Zone Safety & Mobility Rule requirements for work zone performance measurement.

There has been progress. Texas is moving toward statewide use of queue warning systems. Illinois is also. Several other states are working on following suit. But most states only use them on special high impact projects. Some don’t use them at all.

So, I really do want to know. What is holding you state folks back? Why don’t you use these everywhere? I sincerely want to know. Please comment on this post. Let’s talk about it. Perhaps as a group we can find ways around the road blocks you face. And together we can significantly reduce the single largest cause of work zone fatalities nationwide.

Portable Traffic Signals as Work Zone ITS?

20160623_065843Today there are many definitions of work zone ITS. I’ve always felt that just because a device is controlled by electronics and some amount of internal software, does not qualify it as work zone ITS. Good examples are portable changeable message signs or portable traffic signals. In their simplest form they work independently and do not react to their environment.

But recently we started a project with portable signals that should qualify. Before the job bid we suggested portable signals as a cost-effective alternative to hardwired temporary signals mounted on posts and powered by a generator. The agency agreed but asked for most of the optional features mentioned on Horizon’s website. Those included wait time display, drive way assistance device, emergency vehicle preemption, and remote monitoring and notification.

Let’s look at each of these in a little more detail.

The wait time display is a changeable message sign attached to the articulating arm of the signals. When the signal at the other end of the work zone is green, the one facing stopped traffic tells it the maximum time they can expect to wait. Then, once the signal on the other end goes to red, it displays a countdown to green equal to the remaining clearing time.

This is a great feature when the work zone is especially long or when drivers on one end of the work zone cannot see the other end. Like travel time systems, once drivers know what the wait time is, they don’t seem to mind it as much. But not knowing often upsets them.

20160623_065949The driveway assistance device is another clever addition. The display consists of a red light and two flashing red arrows, one pointing right and the other left. When the light is red, drivers are expected to stay put. But when the right arrow is flashing, they can turn right when it is clear. The device ties into the signal phases on the main line. The system knows when traffic is moving to the right and tells the driveway assistance device to inform any drivers there that they may do so, too. It’s similar to a WAIT FOR PILOT CAR sign, but starts the moment traffic is cleared to go in that direction.

Emergency vehicle preemption is the same as most permanent signals use. It immediately turns the signal on the other end red, but still must give the same clearance time before turning to green for the ambulance or fire truck. Because these signals are farther apart, sometimes a half mile or more, the emergency responder must still sit there until traffic clears. Otherwise the potential for conflicts exists. This is one feature I would not recommend again, except when the signals are set up for a conventional intersection where clearing time is minimal. Or when there is an especially high volume of traffic that would otherwise extend the green time without preemption.

Remote monitoring is just what it sounds like. The signals report to a server over a wireless digital modem. All aspects of signal operation are monitored. If a lamp fails, or power drops, or communications between signals are lost; an alarm is sent to everyone concerned via text or email. Signal operations are also logged with each phase date & time stamped. So if a motorist claims they were green when they were actually red, the agency would be able to prove that.

Traffic engineers have taught drivers to expect traffic signals to do certain things. Portable signals can now do anything that permanent ones can do. That reinforces those lessons and makes our work zones safer.

Adapting Existing Technology to Unusual Traffic Problems

The work zone ITS industry has produced many creative ways to help mitigate the impacts to traffic from work zones and to protect workers from that same traffic. But often the problems we solve aren’t the same ones we set out to address. This is true for most industries when they encounter new technology.

According to author H. W. Brand it was true for the movie industry as well. When the first “talkies” were released, “Sam Warner (of Warner Brothers’ fame) convinced his brothers to purchase a technology that allowed the attachment of sound to recording film.” “The initial appeal was that sound would permit theaters to dispense with the orchestras that played accompaniment to otherwise silent films.” Today we can’t imagine movies without the sounds of explosions, gun fire, and, of course, dialogue.  But they were focused on the economic benefits of the technology and so missed what we all see as the obvious artistic advantages.

The same is often true in our industry. Our technologies are more mature now, though new ideas are introduced every day. But too often we miss good opportunities to improve the safety or efficiency of our roads because we don’t have a prepackaged system ready to deploy.

In fact, we do have them ready. We just don’t think it through far enough. Most of our systems use sensors to measure traffic flow, then compare that data to a set of rules, which then trigger outputs like messages to message signs, or alarms at a traffic management center. So it does not matter what your traffic concern is, a system can probably be created to address it. And while such a system could be called “custom”, it won’t normally be saddled with the costs and lead times normally associated with custom systems.

Redding Map

A good example was a demo project done for Caltrans a few years ago. They were closing one of their busiest ramps in Redding for reconstruction. The plan called for them to send traffic to alternate ramps. But no one of those was capable of handling the volumes at the closed ramp. Road-Tech proposed a simple solution. A sensor was placed on each of the alternate ramps. And portable changeable message signs directed traffic to the best alternate. As traffic backed up on the first alternate ramp the sensor detected the stopped traffic. That caused the system to change the message signs to recommend the second alternate ramp. If that ramp backed up traffic was sent to a third alternate ramp.

It was simple, inexpensive, and worked very well. The only problem encountered was public outreach efforts scared everyone away. So the volumes were never as high as expected. But this does show what can be done with the tools we already have. No one talks about alternate ramp systems. But it turns out we had one ready to go. We just didn’t know it.

Next time you are faced with a traffic problem, try to imagine a rule. That rule would say, “If traffic does X, make Y happen.” So if traffic slows I want to change the message signs to warn of STOPPED TRAFFIC AHEAD. Or if average traffic speeds exceed 75 MPH, I want to send an alarm to the police department. If you can come up with a rule, a solution is probably already available. Keep that in mind and you’ll be surprised what can be done!