Work Zone ITS Needs Assessment

The Federal Highway Administration has created a wealth of resources for anyone considering the use of work zone ITS. One of the very best is the Work Zone ITS Implementation Guide published in January of last year (FHWA-HOP-14-008). This great guide helps those considering work zone ITS for the first time, seasoned veterans, and everyone in between.

One of my favorite features is the assessment chart found on page 25. I was reminded of this great tool during a workshop at ATSSA’s Traffic Expo this past February. The speaker, and I wish I could remember who it was, said he uses it every time he is unsure whether the use of a system is justified.

It considers 5 factors with a simple scoring system. Let’s go through it now.

Factor 1 – Duration of work zone
• >1 construction season (10 points)
• 4-10 months (6 points)
• <4 months; procurement and installation timeline is available prior to work starting (3 points)

It is much easier to deploy a system quickly than it once was so I am not sure this is truly a factor any more. But certainly longer projects are easier to justify than shorter ones.

Factor 2 – Impact to traffic, businesses, destinations, etc.
• Significant (10 points)
• Moderate (6 points)
• Minimal (3 points)

You really can’t argue with this one.

Factor 3 – Queuing and Delay
• > 2 miles for periods > 2 hours per day (8 to 10 points)
• 1-2 miles for periods of 1-2 hours per day (6 to 8 points)
• < 1 mile, or queue length estimates are not available but preconstruction, recurring congestion exists for periods , 1 hour per day (4 points)

The value ranges for this factor are going to vary with the agency using them. For some a one mile queue is no big deal, while for others it is a crisis. More importantly you need to score predictable but dynamic queuing higher as it is more likely to result in end of queue crashes. Other factors like sight distance issues (covered below) should also be considered.

Factor 4 – Temporal Aspects of Traffic Impacts
• Unreasonable for a time that covers more than just peak periods (10 points)
• Unreasonable during most of morning and afternoon peak periods in either direction (6 points)
• Unreasonable during most of a peak hour in either direction (3 points)
• Unpredictable, highly variable traffic volumes (1 point)

This could be the “phone call” predictor. Projects that will result in many very unhappy members of the public certainly justify the use of additional tools like work zone ITS. It shows that you care and are working to mitigate the impacts as best you can.

Factor 5 – Specific Issues Expected (0 to 3 points each based on judgment)
• Traffic Speed Variability
• Back of Queue and Other Sight Distance Issues
• High Speeds/ Chronic Speeding
• Work Zone Congestion
• Availability of Alternate Routes
• Merging Conflicts and Hazards at Work Zone Tapers
• Work Zone Hazards/ Complex Traffic Control Layout
• Frequently Changing Operating Conditions for Traffic
• Variable Work Activities (That May Benefit From Using Variable Speed Limits)
• Oversize Vehicles (Percent Heavy Vehicles > 10%)
• Construction Vehicle Entry/ Exit Speed Differential Relative to Traffic
• Data Collection for Work Zone Performance Measures
• Unusual or Unpredictable Weather Patterns

These are all important, and it is easy to imagine a situation where a combination of these alone justifies use of a system. Next to last is data collection for performance measures. This is the most cost-effective way of accomplishing that, and it is required. So I would suggest adding another 5 points or so automatically for data collection.

Once you have scored each factor, you add them up.
30 points or more means you will see significant benefit/ cost ratio from use of a system.
10 to 30 points means it may provide some benefits and should be considered to mitigate impacts.
Less than 10 points means it may not provide enough benefit to justify the cost.

This is simple, easy to use, and should help agencies justify the use of systems where applicable. You may download a copy of the chart by clicking WZITSscore. Please consider sending this to everyone who needs it.

Best Price? Or Best Value?

I remember the first time I bought a cordless drill. I love tools and I was excited to bring it home and try it out. Unfortunately, the batteries didn’t hold a charge for very long, and the drill lacked sufficient torque to do any real work. But I had already spent the money so I was stuck with it. I couldn’t buy another one. I wished I had done more homework before hand. Or that I rented one a few times to learn what features and capabilities I needed in a drill.

Work zone ITS is no different. ITS is now becoming common in work zones. Let me be the first to welcome many of you to our world. It’s a wonderful tool that can save many lives but, like most tools, you won’t know what you need until you have several projects behind you.

As you gain experience, you will add more requirements to your specification. Every job that goes wrong will result in a tougher specification, a new feature requirement, or improved response time from your vendors. This is normal. It’s called learning from experience.

But it would be nice if we had a study or process that leads us quickly and easily through the process of finding the best value system for our needs. Each deployment is a little different. The goals vary from project to project. What works well in one situation may not work at all in the next.

Work zone ITS, like cordless drills, come in a range of quality, features, and prices. Buying the cheapest is rarely a good idea. But how do you get the best value for your needs?

First, don’t buy right away. Rent through an experienced work zone ITS system provider. Get involved in the deployment (see “Get Involved with Work Zone ITS” – 2/24/13) and learn what works and what could use improvement.

Once you are ready to write a specification, I recommend plagiarism. There are several good specs out there. Borrow from them as much as you can. But also try to include something on the following topics:
1. Clearly define your expectations for system performance. What do you want to accomplish?
2. Specify the quantity of sensors, message boards, and other devices needed for your project.
3. Set and enforce standards of performance. If something is not repaired or replaced within X hours, you must deduct that from the monthly charge.
4. Be sure the system is scalable. You may find you need two more sensors or one fewer message board. Make it easy to adjust after the job starts.
5. Understand maintenance requirements. Will you have to expose workers to traffic every day to change batteries, or to do some other work? Or will the system operate efficiently for weeks at a time? And who will be responsible for that maintenance?
6. Communications are critical. Require redundancy in the system. If the devices can’t communicate, they can’t warn drivers of changing conditions. And that could lead to far more serious problems.

Still, I wish a university or research group would come up with a process to help agencies through the process of finding the best value system for their particular needs. It would have to involve some sort of decision tree. But it could also vary recommendations depending on traffic volumes, goals of the deployment, expected queue lengths, etc. Do any of you have a suggestion? Please share them with us.

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: http://www.fhwa.dot.gov/publications/publicroads/14marapr/06.cfm . 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.

An Evaluation Framework for Work Zone ITS

Several interesting papers were presented at TRB this past January. Those were recently made available on the web. We will review and comment on a few of them here beginning with 14-1022: “Effectiveness of Work Zone Intelligent Transportation – Evaluation Framework and Case Studies” by Praveen Edara, Andrew Robertson and Carlos Sun.

They suggest that we need a standard method of evaluating work zone ITS. While I agree with their conclusions, I don’t feel they offer any new ideas in this paper and they don’t go far enough. Their methods are already the recognized approach: measure the effectiveness of the system and compare it to the costs to find a benefit/cost ratio. And the numbers they arrive at are not a full measure of the worth of a system.

Specifically, they suggest we should focus on five measures of work zone ITS effectiveness:

  1. Diversion.
  2. Delay Time (or Travel Time).
  3. Queue Length.
  4. Crash Frequency or Crash Rate.
  5. Speed Based Measures, including 85th percentile, speed compliance or speed variance.

The measure or measures chosen will vary with the goals of each project. By the way, in their review of existing literature, they found that far more papers evaluated work zone ITS results from a traffic operations perspective than from a safety perspective. I think this is a reflection of the reality we have all encountered: everyone claims safety is most important, but actions and dollars normally flow to efficiency.

Anyway, they then chose a measure and after assigning standard values to it, they did the math and found a savings in traveler delay or a reduction in crashes. This was then compared to the cost of the system. What’s new about any of that? It is a good primer on the process, but one with which we are already very familiar.

Here they made a point I disagreed with. They said that when work zone ITS is evaluated on low volume roads, the results are often inconclusive. That makes good sense if you are looking at it from a traffic operations perspective. If you don’t have traffic volumes, there won’t be any efficiencies to be found. But it is not true for safety. Queue warning on long lonesome roads with poor sight distances can be a very effective use of work zone ITS. The systems are inexpensive and one serious injury avoided will pay for it many times over.

They go on to suggest that the benefits of using work zone ITS will be far more apparent on high volume roads, especially those at or near capacity. When we are doing formal system evaluations we should certainly keep that in mind.

But they should have gone a little further. The success of the deployment must be a measure of the degree to which it met the original goals. If those goals were related to reducing delays, then that must be the test. But once you begin to calculate the value of that system, you must go beyond those goals to find the true benefit/cost ratio. Yes, the system saved travelers some time. Quantify that. But it also prevented a few crashes. It may even have saved a life. Those safety improvements should be included in the final calculations or this Evaluation Framework is incomplete.  If we are going to standardize our approach, let’s do so in a way that captures the true value of these systems.

TTI Creates Paradigm Shift for Work Zone ITS

On Monday Ross Sheckler of iCone made an earth shaking announcement. He posted it on LinkedIn and included a YouTube video.  This news changes our industry in a profound and very positive way. You can view the announcement at: http://www.youtube.com/watch?v=_OwaRrffhC8 .

In short, he announced that iCone and their partners have deployed work zone ITS in more than 100 work zones in Texas over the past 10 months. Nothing like this has happened before. In fact, I doubt few, if any of us, even considered it a possibility.

Until now work zone ITS required planning. A system had to be designed and included in the project. Bid packages including the specification for the system and other requirements had to be published. Or a change order adding the system to the project had to be created and approved. All of these things take time….lot’s of time.

But the system now used in Texas eliminates all of that. Texas Transportation Institute (TTI) has created a simple system that any state can use. They model traffic through the corridor based on planned lane closures and their affect on traffic. Once they know what the impact will be they schedule delivery of a work zone ITS system from a preapproved local contractor who has the equipment in stock.

They use two different systems. For shorter closures (and shorter queues), they use what they call a Type 1 system: 1 portable changeable message sign and 4 iCone traffic sensors. For longer closures and queues they use a Type 2 system: 2 message signs and 8 iCone sensors. The contractor, N-Line Traffic, deploys the system just before the closure begins, then picks it all up the next morning.

Everything is budgeted and paid directly by TxDOT. The general contractors are not even involved. This results in a far more efficient use of work zone ITS. The systems only cost money when they are needed and communications run directly between the DOT office that schedules the deployments and the traffic control contractor. So, it will get better results and that means it is far more likely to be embraced by state policymakers.

Other states are considering a similar system. Indiana has already started. And at least two more states will soon follow suit. This will revolutionize work zone safety.  Everyone agrees technology should be used to reduce work zone crashes. But until now doing so involved a great deal of time and effort. Understaffed agencies put the decision off because they did not have the manpower or expertise to ensure a successful deployment.

This changes all of that. There is no longer a good reason not to use work zone ITS. Check out the video and let’s get started!

Maintenance and Work Zone ITS

If you are considering including a work zone ITS system in a project, there are many factors you should consider. First and foremost you should be certain the system you choose will achieve the desired results. Data quality, data format, and real time data availability are all very important. But a third area should also be evaluated: how quickly can your vendor respond when equipment is damaged, stops working correctly for some other reason, or when it must be relocated.

Work zone ITS has come a very long way in quality and dependability in a few short years. But the equipment is still placed near traffic where accidents occur. Hardware can and sometimes will fail. If you include enough sensors, the failure of one is probably not an emergency, but it should be repaired or replaced quickly as the system response won’t be as good as it would be with a full set of sensors.

A more likely issue is data. The sensors may be working as intended, but due to location may not be sending data that fits your needs. For example, you may find it is picking up slow moving vehicles because it is on a steep hill, or near a weigh station offramp. Perhaps the traffic control is causing traffic to slow at that location briefly before going back to full speed. In any of these cases you may need to move the sensors to a better location so the system does not send out false alarms.

Construction activity can also cause issues. Workers may move a sensor out of their way as the paver moves past it, and then move it back once they are beyond it but without aiming it properly. The sensor shows there is no traffic because it is pointed at a flock of sheep rather than at the road. Or slow moving construction equipment, if detected by the sensors, will trigger false alarms.

This varies with the type of sensor as well. Some require more frequent attention than others. Simple radar is more forgiving. Side fire microwave sensors like Wavetronix or RTMS must be aimed precisely and calibrated at each location. Wind and vibration cause sensor trailers to move and can affect the output.

So it makes good sense to require local service and support. What the response time must be will vary greatly from project to project. Problems with one device in a travel or delay time system probably can wait for a day or two. But a sensor out in a queue warning system for a blind curve must be corrected much faster – usually in less than a few hours.

Be very specific with your expectations.  Let everyone know going in what the maximum allowable downtime is for each device, each feature and for the software and server controlling them. That time will vary by device. The server and software must be up and running 24/7. Sensors are probably the second most important. Cameras and message boards are next. Alarms to users are probably last.

Consider including damages for downtime beyond the allowed maximum for each device and for the system as a whole. The number you choose should be a reasonable percentage of the total system cost. It might be the cost per day charged by the vendor for that device if that cost is known. Or you might use the system cost per day divided by the number of devices (less some percentage for the software, server and website). The important thing is to make both your expectations and the consequences if they are not met very clear to all concerned before the project bids. Then the vendor will know his or her costs going in.

But however you choose to define your requirements, be sure to include local representatives on call and available to make the little adjustments every system needs to operate at peak performance.