The Work Zone ITS Blog – Post #100

canstockphoto4235293This is post number 100 for the Work Zone ITS Blog. So I hope you will humor us as we celebrate this milestone and look back on the past few years in our industry. The blog began in August of 2012. The goal was to initiate a conversation on work zone ITS. We imagined lots of public comments and a lively discussion on topics of interest. That has not been the case. Too many of you are shy or prefer to keep your opinions at the unofficial level. And that’s OK.

It has been well worth doing anyway. We get lots of comments, but they are back channel rather than public. Many of those have led to additional posts. So thank you all for that help.

Our industry has changed significantly over these past four years. Acceptance of work zone ITS is greater than ever before. We have gone from a deployment here and there to required use in states like Texas. Other states like Illinois and Indiana are now using systems on most major projects. Many more states are ramping up their use of these systems, as well.

Manufacturers have come and gone. Some that are still here have changed their business models. Most manufacturers now understand that a local presence is important to provide agencies with fast, frequent service of their systems. So those manufacturers are building relationships with local contractors.

The technology has proven itself. LEDs, batteries, solar systems, and digital communications have all greatly improved. In particular, 4G modems and the cost and availability of satellite communications have made great improvements. Those improvements have resulted in systems that are easy to deploy and super-dependable while reducing costs at the same time.

Our systems will continue to evolve, adding more features and seamlessly integrating with other systems and devices. Work zone ITS is already very cost-effective. Pricing may continue somewhat lower, but most cost reductions will come at the contractor level as they amortize their fleets and learn what their true costs of deployment are.

New challenges lie ahead, especially with regard to automated and autonomous vehicles. There is a lot of talk about our place in that new world. And as that becomes clearer, it will be interesting adapting our systems to help guide driverless vehicles through our work zones safely and efficiently.

Finally, as we start 2017, I would like to thank those of you who have been here since the beginning. You know who you are. About 25 of us have been in this more or less from the start. That group includes manufacturers, contractors like Road-Tech, and some state DOTs. You are the true believers and it is because of your vision and hard work over these many years that have made this all possible. We have a bright future ahead of us and we look forward to working with you all.

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.

Variable Speed Limit Signs

VSL UtahAt the recent National Rural ITS show held in Utah, a workshop was presented on the subject of variable speed limit signs. The speakers included Lynne Randolph from the Southwest Research Institute who talked about VMS use in Texas, Brian Christensen of Horrocks Engineers and Glenn Blackwelder of Utah DOT who discussed the local VMS installation on I-80 between Salt Lake and Park City, and Josh Crain of DKS who talked about the use of VMS in Oregon.

This technology remains one that makes good sense in theory, but whose complete affect on traffic is still not fully understood. This workshop filled in some of the blanks but there is more work to be done.

In short, a variable message sign system measures traffic speeds as conditions change and then displays the 85th percentile speed rounded down to the nearest 0 or 5 on regulatory speed limit signs upstream. The idea is to smooth traffic flow and reduce the speed variance that occurs as drivers begin to respond to changes in weather, traffic volumes and construction work.

The speakers shared some interesting lessons learned. Utah’s installation seemed to be the most successful. They have a total of 15 VSL signs through Parleys Canyon, a very steep climb from Salt Lake City east to Park City. There are 8 signs eastbound and 7 signs westbound. The other deployments discussed had far fewer signs or in Oregon’s case, they are single installations spread over the state.

Utah also posts VARIABLE SPEED LIMIT SYSTEM AHEAD signs at each end of the canyon. For these reasons they are far more visible and, I suspect, gets better results.

Utah did find that the white LED displays washed out behind a sign covered in the standard white reflective sheeting. To overcome this they added a black band around the speed display. You can see in the photo above that this change greatly improved the contrast so the signs are now easy to read in all light conditions.

The four speakers seemed to agree that drivers were more inclined to respect lower VSL speed limits when weather or construction activity justified the change. They did not respond as well when limits were lowered due to congestion downstream. Drivers need to know why they should slow before they respond.

Utah’s signs are enforceable. Texas’ signs are not. Oregon has installed some of each. They have developed a decision tree that weighs local conditions and the reasons for the installation to determine which type should be used in each situation.

It was a very informative workshop. I encourage you to download it when it becomes available.

Work Zone Risk Factors For Rear-End and Sideswipe Crashes

The third TRB paper I would like to discuss is paper number 14-3840: “Work Zone VS. Non-Work Zone: Risk Factors Leading to Rear-End and Sideswipe Collisions” by Claire Silverstein, Justin Schorr and Samer Hamdar of George Washington University.

I co-chair California’s work zone safety committee. One of our members, Pat Fyhrie of U. C. Davis Advanced Highway Maintenance & Construction Technology (AHMCT) research group has been reconstructing work zone crashes to better understand where the majority of crashes occur. She has found that most are rear-end or sideswipe crashes and a majority of those occur alongside the work area within the work zone.

This TRB paper takes this a step further. They have found that rear end and sideswipe crashes occur in work zones more often when “there is no precipitation, during daylight conditions, with limited roadway curvature, and when increasing number of lanes and speed limits.” In other words, the results are counter-intuitive. The “safer” the work zone appears, the less safe they become.

This makes more sense when you look at it from the driver’s perspective. He or she will slow down when it rains, or when the lanes are narrowed or shifted, or when they are traveling near temporary concrete barrier. But when the road straightens out and opens up, it’s pedal to the metal time!

The paper comes to the conclusion that there are many opportunities to use technology to help prevent these crashes. Some of that technology will (eventually) be in-vehicle. Automated enforcement should be considered. But a third area of opportunity is work zone ITS. The authors write, “potential ITS applications should be targeted at creating safer traffic flow conditions by encouraging safer driver maneuvers.”

Queue warning systems, Variable Speed Limit systems, and Dynamic Merge systems come quickly to mind. All three are low cost systems that are easy to deploy and that help to smooth traffic flow and reduce speed variance – the primary cause of both rear-end and sideswipe crashes. V2V systems will one day do this automatically. But that day is still many years away. Work zone ITS can do it today, dependably and cost effectively.

Pooled Fund Studies and New Product Development

I recently participated in an Enterprise pooled fund study to develop an Intersection Conflict Warning System (ICWS). We will talk more at some future date about the system. But today I would like to talk about the process. I am a businessman. I have always been a little uncomfortable with government designing product. In my experience market forces will always do a better job of design and refinement than a committee could possibly do.

But in this case someone needs to dictate how the system should work. In terms of technology, this is a simple system. But sign placement, when it should display warning messages and for how long, the effects of turning movements on those design parameters, fail safe modes, and many other performance specifications cannot be left to each manufacturer to decide separately.

The agency may be found liable if the system does not do those things correctly. It is in their interest to clarify their expectations up front. There are also several of these systems in use already in states like North Carolina, Iowa and Missouri. To maximize their effectiveness and to prevent confusion, the appearance of the equipment and the way it works must be consistent from state to state. So for both of these reasons it made good sense to decide those questions now.

The group began last year with a series of conference calls. The first ones resulted in a high level list of needs and wants for such a system. Then general functionality was described to support those needs. Finally, the group began to set actual parameters for the system performance. Things like on time and off time for the different signs, distance in advance of the intersection where signs should be placed and where vehicles should be detected. These discussions were difficult over the phone so they decided to hold a face to face meeting to hash them out.

A total of nine people were at that final meeting. One county DOT and four state DOTs were represented including a current member of the National Committee on Uniform Traffic Control Devices. Two of us from the American Traffic Safety Services Association (ATSSA) were there to represent industry, one from the sign industry and another (myself) from the rural ITS industry.

The group was led by Ginny Crowson of Athey Creek Consultants. She did a wonderful job of keeping us focused and on track. The group was championed from the beginning by Jon Jackels of Minnesota DOT. Unlike many agency folks, he pushed for industry involvement. He didn’t want to get months down the road with this process only to find out that industry either could not or would not manufacture the system.  He knew it would take a little longer with everyone participating, but he also knew the results would be far more developed and ready for market.

Everyone there was passionate about highway safety and the use of technology to improve it. There were disagreements but they were always held to the same standard: which idea will result in better, more cost-effective performance. I believe the size of the group was just right, too. Everyone could be heard and a trust developed quickly between the group members.

The meeting ran from noon the first day to noon the second day including another two hours during and after dinner. We didn’t get everything done, but we came very close. The most difficult and time consuming issues were all covered thoroughly resulting in a consensus on each one.

This is a process I would recommend any time a new product or service would benefit by starting with the performance requirements. We did not discuss how companies should design their systems to meet these parameters. The choice of technologies will be left up to each manufacturer. We were only concerned with what it had to do and whether it was feasible and cost-effective.

Intersection Conflict Warning Systems

Last month we talked about work zone ITS. This month, in the interest of equal time, we will delve into rural ITS. Minnesota DOT and the Enterprise Pooled Fund Study have been leading a nationwide effort to advance and promote intersection warning technologies. I am excited about this for a number of reasons not least of which is that it uses technology in areas where they have not been used before. We are accustomed to seeing ITS deployments on freeways and major arterials in and near cities. But uncontrolled intersections on two lane roads have not benefited – until now.

These systems have been used since 1998 to warn drivers at stop signs that cross traffic is approaching and that it will not stop. System architecture has evolved and  varies still but most include sensors to detect approaching traffic on the main line.  The approach speed is detected and analyzed to see if it is a danger to cross traffic. If so, some form of blank out sign is turned on to warn cross traffic.  These are simple, usually solar powered, and cost as little as $30,000 per intersection.

We have all enjoyed success driving down the number of fatalities and serous injuries on our roads. But there is still much work to be done on rural roads. They account for more than half of all fatalities yet only 30% of the vehicle miles driven. A major portion of those fatalities occur at rural intersections. Drivers stop and then pull right into the path of oncoming vehicles. Usually this is due to line of sight or gap acceptance issues. For whatever reason they fail to truly “see” the oncoming traffic.

Early study results have shown excellent results from intersection warning systems.

There are some ongoing discussions:

  • What should the warning signs look like? Some guidance is available and presentations have been made to the National Committee seeking further direction.
  • What are the legal implications? This is a supplemental device. There is still a stop sign at which drivers must stop and look both ways before proceeding. So the thinking is that even if the warning system failed to warn, the driver is still responsible. Many systems include multiple redundant sensors and a log of traffic detected, speeds, and warning triggers with date and time stamp.
  • These can’t be placed everywhere, so where should they be used? Clearly intersections with high concentrations of crashes should be the first ones. But after that?

Another advantage of these simple systems is their portability. If you have an intersection with frequent crashes and you plan to realign it, or add signals, or some other mitigation when funding becomes available, this is a low cost way of “fixing” the problem until you can afford to do more. Afterwards, you can move the system to another intersection.

What can we, as an industry, do to promote these systems? What questions do you have about system architecture? Are there any issues I haven’t mentioned? Let us know what you think!