Common Mistakes in Work Zone ITS Lessons Learned During 20 Years in This Field

Today, we would like to discuss common mistakes agencies make when including work zone ITS in a project. But we don’t want to scare anyone away or make this more difficult than it really is. Today, work zone ITS is easy to use, easy to contract, and easy to evaluate. So please dive in and learn your own lessons as you go along.

But with that said, there are a few bits of advice we can offer from our many years deploying these systems.

The first is simple enough. Before you specify a system in a project, identify and clearly state your agency’s goal for that system. Is it end-of-queue crash reduction? Is it diverting traffic onto alternate routes? Is it speed reduction? You and every other decision maker in your agency need to agree on the primary goal, and then communicate that goal to the system supplier through your specifications.

Second, don’t try to do too much with your system. Focus on that primary goal first. If the system supplied can also handle additional responsibilities, then add those that help you meet any secondary goals. For example, a queue detection system can also provide traffic data to meet the Federal Work Zone Safety & Mobility rule. But don’t add features that will just bombard you with data you can’t use. You will have plenty to work with as it is.

Once you have your goal for the project, you can begin designing your system. If the goal is reducing rear-end crashes in slow and stopped traffic, doplar radar is the best sensor to use. It works well at low speeds and is inexpensive. But if your goal is to replace a permanent system that measures speeds, counts and classifications, a side-fire radar such as Wavetronix or RTMS.

Next choose your sensor locations. For most systems you will space them about three-quarters of a mile apart. You may get away with as much as a mile or more in some situations, but more often you will want them between a half-mile and a mile apart. Once they are in place and collecting data, check that data to be sure it is what you need. Locations with a lot of concrete barrier sometimes result in radar echo giving you false results. Locations such as a gore point at the on-ramp from a truck scales will result in below-average speeds as trucks slowly speed up onto the mainline.

Budgets often force you to limit the scope of your system. If it comes down to a choice between cameras or more sensors, please consider maximizing the number of sensors. Better, richer data will result in a more responsive system, and one less susceptible to service interruptions. If you must have cameras, limit their use and the video frame-rate to keep your wireless expenses lower.

Your specifications should include the type and quantity of sensors, message signs, camera trailers and other devices. And consider including a line item for each type of device. In that way, you will have a price if you find you need to increase or decrease the quantity of devices.

Finally, dig into your data. Learn what makes the system work. When an incident happens, look at the data to learn how quickly it affected traffic upstream. And how quickly it clears once the cause has been corrected. This will give you a better sense of the capabilities of these systems and how best to use them on future projects.

Alternative Funding for Work Zone ITS Fact Sheet

Nearly everyone who understands work zone ITS knows it is a cost-effective way of mitigating the traffic impacts of major and sometimes even minor road construction projects. Studies have proven the value of these systems. But DOTs will often tell you they don’t have the funding to pay for it.  The FHWA encourages states to use work zone ITS. They will pay for these systems through conventional construction funding. So, when states say they don’t have the funding they mean they haven’t found a pot of money outside of the money they use for asphalt and concrete.

FHWA wants to address that problem. They have just published the “Alternative Funding for Work Zone ITS Fact Sheet”. In it they document how Illinois uses HSIP funds to pay for Work Zone ITS. Download a copy of the fact sheet HERE.

FHWA says this is a highly underutilized funding mechanism. According to the fact sheet, “While some states use HSIP funds for work zone purposes, many state DOTs do not tap into this resource. Out of the more than 4,000 HSIP projects referenced in the 2016 HSIP National Summary Report, only 13 were work zone-related projects.”

Work Zone ITS Blog addressed the efforts of Matthew Daeda and Illinois DOT on May 12, 2016. We told you that this contracting method offers several advantages:

  1. The state only pays when the system is needed.
  2. They work directly with the vendor and that greatly improves communication.
  3. Staff has direct access to the system data and to make changes.
  4. By bidding for each district local companies are more likely to win, thus reducing response time.

 

This fact sheet is a BIG deal! States are always saying they don’t have the funding. This is one way of getting it. And the Feds aren’t just allowing this. They are encouraging states to use HSIP funds for work zone ITS.

States do need to identify work zone safety as a SHSP Focus Area and provide the data to support that decision. According to the National Work Zone Safety Information Clearinghouse, there were 799 fatalities in US work zones in 2017, up from the previous three-year average of 764. That’s not much when compared to the total roadway fatalities of 37,133.

But work zones are always a safety issue. States can and should include them in their Strategic Highway Safety Plans (SHSP) for a variety of reasons. Work zones force drivers to process more information and react faster than they normally do outside of work zones. That’s why crashes attributable to distracted driving, speeding, aggressive driving, and impaired driving often show up first in work zones. Furthermore, solutions that work in work zones may have applications elsewhere.

In 2017 overall fatalities declined nationally while work zone fatalities increased. Any state with this same disparity should include work zones in the SHSP. Many states have recently increased funding for road construction. They, too, will unfortunately see an associated increase in work zone fatalities. And, again, they to should include work zones in their SHSPs.

This is a wonderful tool. Thank you to Todd Peterson and Jawad Paracha for putting it together. Now we all just need to get his in front of the decision makers in our states!

 

How Does the Traffic Message Channel Work?

We’ve talked in the past about the need to update the work zone information on digital maps in real time. But how does that process actually work? The answer is surprisingly simple while offering far more detail than you might expect. It is sent over FM radio and satellite channels using RDS-TMC protocols. RDS stands for “radio data system”. TMC stands for “traffic message channel”.

The information is sent in very small packages several times a second within a frequency used for digital identification of the station, song titles, etc. In this way, location codes and event codes are sent without interrupting the audio and updates any navigation devices in very near real time. That information can then be used in calculating the fastest route. It will also recalculate as incidents occur that cause significant delays.

In the United States the digitally coded traffic updates are distributed by Navteq over FM channels and by Sirius/XM satellite radio. iHeartMedia and TeleAtlas also provide commercial services in about 77 US metro areas.

Once received, the codes are automatically displayed in the driver’s preferred language making them more readily understandable and therefore more effective.

Each incident is digitally coded and sent as a TMC message. Each message consists of an event code, location code, expected incident duration, and other pertinent details. The message includes one or more phrases describing the problem. The first portion states the problem and the second portion gives clarification regarding the types of vehicles affected, recommended actions by the motorist, etc.

As you might expect, there are many work zone related messages. In fact, there are more than 150 work zone specific messages as well as many hundreds of messages just focused on queue length, travel delays, and lane closures. The work zone messages get fairly specific: mentioning pavement marking, resurfacing, bridge work, water main work, etc. They even mention temporary signals in one.

There are also many messages about incidents, weather, and special events.

The RDS-TMC system was developed before wide-spread use of GPS. So, they do not use a lat and long to identify the location. Instead location is described in relation to major intersections and points of interest.

As work zone reporting becomes more sophisticated, codes can still be added to provide additional detail such as the lanes that are closed, the length of the closure, expected delays, and more. Only a little more than half of the code capacity has been used so far. So there is plenty of room to grow. And that is important. Because autonomous vehicles will require far more detail. Discussions are already underway regarding what new details must be included and the formatting, etc. for them.

Is There an Ideal Sensor Location?

Are there “perfect” sensor locations? For example, when we deploy a queue warning system, are there sensor locations that will get us better data? Could that data inform us of slowing traffic sooner? Or could it be a better indication of traffic conditions than data from another location would be?

For end-of-queue warning systems we submit that the ideal sensor location is just upstream of where queuing is most likely to begin and, therefore where average speeds vary most.

There are locations like that throughout the work zone. Narrowing of lanes, lane shifts, temporary concrete barrier, bridge falsework and other construction activities affect drivers sense of safety. Anything that negatively affects that feeling of comfort will reduce the 85th percentile speed.

Short on-ramps with reduced merge distance have the same affect. However, if traffic always quickly accommodates those merges and returns to the previous 85th percentile speed, then that is not a perfect location. Only when the geometry in combination with traffic volume results in dynamic queuing does that become a good sensor location for queue warning systems.

The power source is our greatest limiting factor today.  Batteries, solar systems, etc. take up space. They must be located where we can reach them easily for maintenance. For this reason, many sensors are located on message signs and arrow boards where they can draw power from them and even share communications devices.

Arrow boards are placed at the taper. Queuing begins there, of course. But we will only catch speed variance due to conflicts at that merge point. We won’t see if that variance continues upstream.

Message signs are placed in advance of the work to warn of slowing downstream. We should always place one sensor at a point that queuing would reach as a result of a worst-case scenario. And a message sign location may be able to serve both purposes. But we normally want the sensors located where queuing begins and we want the message signs located upstream to warn of that slowing – not located together. If sensors and message signs share the same locations they are likely either too close to the work zone or too far from the source of the queuing to warn traffic before they reach the problem area.

We generally space sensors out every half mile to a mile apart with the understanding that we will learn about any queuing quickly. And that is a good approach. After all, we can’t predict all causes of queuing. But couldn’t we adjust those locations a little one way or the other to catch these obvious causes of slowing a little earlier?

It would be helpful to see research into sensor location. But in the meantime, let’s evaluate our work zones and adjust our sensor locations to monitor the more obvious sources of slowing. Our systems will perform better and improve work zone safety even more than they do today.

Final Report on Every Day Counts 3

USDOT has published their final report on the activities included in Every Day Counts 3. That included the promotion of work zone ITS. We talked about their efforts in past posts (10/27/14 and 12/14/16 ) and applauded both their efforts and the results, but now we can look at the final numbers. Read the report HERE.

When they began in January 2015 there were 7 states that had already made the use of technology to reduce work zone traffic impacts a mainstream practice. 8 more states were in the assessment stage at that time. Bu December of 2016 – just two short years later – 11 included work zone ITS as a mainstream practice and 13 more had moved to the assessment stage – a 37% increase!

More important, those efforts are already bearing fruit. Wisconsin’s initial tests indicate a significant reduction in end-of-queue crashes. They are now working with a university partner to develop a queue warning system decision support tool to help project designers know when to include a system in their jobs.

Illinois DOT has awarded on-call contracts to provide work zone ITS system in three of its districts. They, too have studied the effectiveness of these systems. Once they finalize their research they plan to incorporate that in their future system deployments.

Massachusetts DOT “uses smarter work zone technology applications in all construction work zones that meet a specific impact level and a preset scoring criteria threshold.”

And New Jersey DOT developed scoring criteria for designers to use when determining whether work zone ITS should be included in a project. Work zone ITS was also added to its preliminary engineering checklist as a tool for mitigation of work zone impacts.

Thanks again to FHWA for their foresight and hard work on this. It was just the push states needed to get started in work zone ITS and is sure to save a great many lives in the years to come!

 

The State of the Work Zone ITS Industry – 2018

We just enjoyed the 4th of July holiday. As we sat on the deck consuming bar-b-que and adult beverages we considered the state of the work zone ITS industry. We really have come a long way in the past year and that deserves recognition and a quick look back.

One of the most important and most overlooked recent changes is the blurring of the lines between the permanent ITS infrastructure world and the work zone ITS world. At last month’s ITS America show in Detroit, HERE demonstrated their new ability to incorporate live data feeds from work zones along with their partners including software provider GEWI and work zone ITS supplier iCone.

Waze is also incorporating real-time work zone data feeds in their traffic reporting. Both traffic data providers understand the importance of immediate and accurate work zone reporting and are working internally to make better use of our data.

This blurring is going the other direction as well, as Work Area Protection (formerly ASTI Transportation) now offers the option of including Iteris probe data in work zone travel and delay time calculations.

This blurring of the lines may be more important than we realize. Because it becomes less about us versus them for funding and more about an ITS system that works all of the time – especially in work zones. Work zones have always been an afterthought with ITS practitioners. But that is changing. They now understand that the single largest cause of nonrecurring congestion is work zones. And they are working to address that with their permanent systems.

In a recent article in Better Roads Magazine Frank Zucco of Wanco explained that work zone ITS is now much less expensive. Large, elaborate systems are still available and make sense for multi-year projects with major traffic impacts. But more and more simple systems are now being used for queue detection, trucks entering and dynamic merge applications. And, as Frank points out, those are now very dependable and inexpensive, making them a cost-effective solution for most projects.

Research now validates what we all knew intuitively. Queue detection, in particular, has shown major benefits according to the Texas Transportation Institute and AASHTO. We touched on this milestone two years ago in our post “The State of the Work Zone ITS Industry” published on 4/28/16.

And, lastly, work zone ITS helps facilitate the proliferation of automated and autonomous vehicles. Without real time reporting of work zones, AVs are left to navigate them on their own. And the AV world now understands that. We have become a part of the conversation. At the Automated Vehicle Symposium later this month in San Francisco sessions about work zones will be included for the third year in a row. See #33: “OEM/DOT Dialog on Dedicated Lanes, Work Zones and Shared Data” on July 11th. Autonomous vehicles are a big story that will only get bigger. Funding and research will flow to our industry as a result of these conversations.

As an industry, we aren’t yet to the point where our systems are used everywhere they could help. But we can finally see that light at the end of the tunnel.

Work Zone Traffic Control “Down-Under”

We just returned from a wonderful trip to Australia where we spoke to the Traffic Management Association of Australia (TMAA) about work zone ITS. Their members were all excited and focused on finding safer, more efficient ways to manage their work zones.

The program was packed full of interesting speakers and a variety of timely topics. They also gave us all just the right amount of time to discuss those topics between sessions. It was very well run.

The attendees seemed to enjoy talking to Americans and all asked what we thought of the meeting. My first answer was always the same: traffic control companies in both countries share the exact same set of problems:

1) Speeding in work zones.

2) End-of-queue crashes.

3) Hiring, training and retaining good employees.

4) A perception by the driving public that we are there to make their lives miserable.

5) Insufficient funding for maintenance and construction.

6) Changing standards and levels of enforcement from one state to the next.

7) Varying commitment and funding levels from one state to the next.

Just like ATSSA, the TMAA brings contractors, manufacturers, academia and government agencies together to discuss these problems and identify solutions. The TMAA does an especially good job of this. We look forward to learning more from them in the years to come!