Does Size Matter?

Today let’s talk about another important feature of today’s work zone ITS systems: scalability. This is a feature often overlooked. Industry doesn’t mention it because they take it for granted. But we should. New and potential users of our systems don’t understand how simple it is to add or subtract devices to arrive at a system scaled to fit each project.

We just finished up a short term project in Sacramento known as Fix50. It required the closing of multiple lanes on this important route through downtown. Significant queuing was expected. Instead of a typical queue warning system consisting of 4 or 5 sensors and 2 or 3 message signs, this was much larger. Queues were expected to extend at times to more than 2 or 3 miles. Furthermore, the project ran between two major interchanges and queuing was expected to back up onto those other routes.

Sensors and message signs were placed on both Hwy 50 and on the freeways that intersected with it. Drivers on Hwy 50 saw messages like SLOW TRAFFIC AHEAD, PREPARE TO STOP. Drivers on those other freeways saw messages like SLOW TRAFFIC ON EB50, PREPARE TO STOP.

Earlier this month this blog discussed a new article written by Tracy Scriba of FHWA. She wrote about the value of queue warning systems. “Using technology for queue detection and warning can be particularly effective when queues are unpredictable and therefore unexpected by drivers. When it is difficult to predict when and where queues will occur, it can be challenging and costly to use manual methods, such as to have sufficient staff available to cover extended time periods, and to keep the warning device (enforcement vehicle or truck-mounted dynamic message sign) in the proper location relative to the end of the queue.”

She went on to back this up with new data supplied by Illinois DOT: “In an analysis of queue detection and warning systems implemented at several work zones by IDOT, crash statistics from 2010 (prior to system implementation) and 2011 (after system implementation) showed nearly a 14-percent decrease in queuing crashes and an 11-percent reduction in injury crashes. These reductions occurred despite a 52-percent increase in the number of days when temporary lane closures were implemented.”

This represents a significant improvement in safety. We don’t always have before and after data we can compare, but we know queue warning systems have reduced the number of crashes on the projects that used them.

This also results in a significant improvement in system efficiency. Fewer crashes mean fewer delays. And both are true for large projects as well as smaller ones. And because these systems are scalable, the cost of a queue warning system is proportionate to the size of the project. So these benefits are available to any project, large or small, where queuing will be a problem.

New Article by Tracy Scriba in Public Roads

FHWA’s Tracy Scriba recently published an article on work zone ITS entitled, “Creating Smarter Work Zones” (Publication number FHWA-HRT-14-003).   Please read it at: . It is a short article but makes several excellent points. We will touch on a few of them here.

She begins by making a case for the need for more and better tools to improve work zone safety. Then Tracy provides this quote:  “The success stories of technology used to mitigate work zone impacts continue to mount nationally, to the point that the traveling public is now beginning to expect and even demand it,” says Gerald Ullman, senior research engineer at the Texas A&M Transportation Institute. “I believe that those agencies and contractors who learn how to best incorporate work zone technology into their decision making processes and ways of doing business will be the most successful and profitable in the future.”

Ms. Scriba then adds, “Technological solutions once were limited to a single purpose and operated independently. …agencies now can integrate solutions over multiple platforms to analyze data and provide travelers and work zone practitioners with the knowledge they need to make informed decisions.” Both of these comments point to the growing acceptance and use of work zone ITS systems and to the fact that the more they are used, the more additional benefits have become apparent. Now we aren’t just improving work zone safety and efficiency, we are also collecting valuable data that can be used to measure the effectiveness of those work zones.

This blog has often discussed the disconnect between work zone practitioners and ITS practitioners. Tracy explains it very well. “As in other areas of technology, practitioners may have difficulty staying abreast of current technologies, especially if their primary expertise is design or construction. ITS staff members often do not interact with construction staff, leading to reduced understanding of work zone issues by those with the technology expertise. Similarly, design and construction staff may have limited awareness of what technology is available, a reluctance to use technology or ITS, or difficulty in using it effectively.”

Finally she touches on another topic we have touched on previously and that is a tiered standard special provision for work zone ITS systems. “To help guide its decision making, (Illinois DOT) is establishing a policy for the use of different types of smart work zone systems. “One of our key lessons learned was that we need to develop a tiered statewide contract special provision for ITS that will allow for competition between all smart work zone systems and establish a policy to guide where we want to use these different types of systems,” IDOT’s Nemsky says. “In the past, it’s been decided on a project-by-project basis based on [our] knowledge of the project area, traffic incident data, and sight distance issues. We also do queuing analysis for all interstate projects. We are envisioning having three different tiers in our policy and special provisions to recommend different types of smart work zone technology based on factors such as whether a project is on an urban or rural interstate and what level of delays are anticipated.”  Many states are now taking this approach including Illinois (quoted here),Texas and Indiana. Several more are changing to this approach including Oregon.  Experience has shown that construction design folks who aren’t yet comfortable with work zone ITS, can use a system like this to quickly and easily specify a system appropriate for each project.

Publications like this one help speed adoption of work zone ITS. Please pass it on to anyone involved with work zones. And let’s hope Tracy Scriba continues to write these wonderful articles.