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!

 

FHWA Work Zone Data Initiative

We in the work zone traffic control world and specifically the work zone ITS world have long wrestled with how best to gather and evaluate work zone data. This has been a topic of discussion at conferences, peer-to-peer exchanges, and in DOTs nationwide. These systems are now providing a great deal of data and the FHWA feels it is time we settled on a standard approach to that data. In response, they have launched the Work Zone Data Initiative (WZDI).

The stated goals of the initiative are:

“To develop a recommended practice for managing work zone data.” And to “create a consistent language for communicating information on work zone activity across jurisdictional and organizational boundaries.”

They are working to develop a specification for work zone data that supports DOT efforts throughout the project and also allows some sort of standardized evaluation and comparison once that project is complete. They want the data to become more useful for project planning, for real-time traffic operations, and for post project analytics.

This is something our industry must be involved in. Please let us know if you are. But if you are not, please contact Todd Peterson, FHWA Work Zone Management Team Transportation Specialist to express your interest. His email address is Todd.Peterson@dot.gov .

 

USDOT has also announced a competition on Advancing Innovative Ways to Analyze Crash Data. They point out that most crash data (as well as work zone data) is siloed and made available only on an annual basis. By opening those sources of data up, DOT hopes to take advantage of new tools such as machine learning (see 4/10/17 post) to gain insights on ways we can reduce roadway fatalities.

This effort is not work zone specific, but could result in improvements that our past state and project specific analysis was unable to find.

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!

The Importance of Crash Modification Factors to Work Zone ITS

A webinar was held December 5th on work zone crash data collection and analysis. It was organized by Wayne State University and included speakers from the University of Missouri and Michigan State University. A recording of the webinar will be made available soon.

Several very good resources were made available as the webinar began including “A Guide for Work Zone Crash Data Collection, Reporting, and Analysis” which was produced for the FHWA by the Wayne State University College of Engineering. This guide can be found at:  https://www.workzonesafety.org/files/documents/training/fhwa_wz_grant/wsu_wz_data_collection_guide.pdf

As a work zone ITS practitioner, I have deployed many systems over the years but have very little data to prove the effectiveness of those deployments. The problem has always been establishing a base line of the probable number of crashes given the traffic control, project duration, traffic volumes, etc. Only with that base line can we compare our actual crash numbers to determine whether the system was cost-effective.

The crash data guide states the problem very succinctly, “In order to perform an effective work zone safety analysis, the appropriate work zone crash data needs to be available. The availability of this data is only as good as what is collected on the state crash report form.”

The webinar pointed to several states’ best practices in this regard. At a minimum, states are required to include a checkbox on their form to indicate if the crash was work zone related. But states including Connecticut, Iowa, Minnesota, Pennsylvania and Virginia collect much more. They go into detail about the location of the crash within the work zone, and what types of traffic control and construction activity was in place at the time of that crash.

That data will help them develop Crash Modification Factors (CFMs) for different traffic control treatments. In time we hope to see CFMs for queue warning systems, dynamic merge systems, variable speed limit systems, and much more. Those CFMs could be specific to high volume multi-lane facilities, rural four lane highways, etc.

Once CFMs are developed, the rest of the process is fairly simple. Compare the CFM associated with your proposed system to the traffic volumes where that system will be used, and you will know immediately whether the use of that system is justified. The use of these systems is already taking off, but there is still some guess work involved in the decision to use or not use work zone ITS. By developing CFMs we could speed that process along and make it more scientific.

5G Cell Service and Opportunities for Our Industry

By now, most of you are aware that 5G phone service will be here soon. But you may not understand what that means for our industry. An article written by Hongtao Zhan of SureCall and published recently in VB talks about its potential:

https://venturebeat.com/2017/09/30/5g-isnt-just-faster-it-will-open-up-a-whole-new-world/

As the article points out, download speeds could be as much as 100 times faster than we currently experience with 4G service. This service will be expensive at first but once everyone has switched to 5G devices those faster download speeds could result in greater use of video as data rates eventually decline.

But the most important aspect of 5G for our purposes is latency. Latency is a measure of how quickly critical data is transmitted. 5G offers near zero latency. This will enable an incredible array of new technologies affecting every part of our lives. That is why “Qualcomm is calling 5G the “platform for invention.””

Mr. Zhan describes ways 5G could be used for things like haptic controls in vehicles for purposes such as lane keeping, collision avoidance and more. For our world haptic controls mean we could deploy “virtual rumble strips” in advance of work areas to wake up drivers and perhaps even to return control of autonomous vehicles over to drivers.

Zero latency means workers could be removed from the work area and could perform many dangerous operations remotely using a virtual reality head set and controls. For example, they could “drive” TMA trucks remotely. We might also create a remote control cone setting machine. Striping trucks and RPM installation might also be automated.

How about a phone app to warn workers? With near zero latency, we could create an intrusion warning system that works fast enough to save lives, while requiring very little in additional equipment – just the smart phones everyone is already carrying around. The work area could be delineated on a digital map and any vehicle crossing those lines would trigger warnings to anyone in the area who has downloaded the app.

The possibilities are endless and this new communications protocol is right around the corner. It is time for us to begin thinking about how we might use it to improve safety and save lives.

Caltrans QuickMap to Add Waze Data

 

Caltrans recently announced changes to their popular QuickMap travel app. The app is available online at http://quickmap.dot.ca.gov/ and from your app store for both Apple and Android. In QuickMap users choose what they want to see, and the area they are interested in seeing, and a custom map shows them exactly that and no more. Travel times and factors affecting travel times such as work zones, weather and other incidents are all displayed in near real time.

They have now added an option to see Waze data. This is significant to those of us interested in work zone ITS because Waze displays iCone sensor data as work zone locations. For example, Road-Tech currently has an iCone system on SR99 in Fresno and the work zone is displayed in QuickMap with an icon of a worker in a hard hat:

Eventually these icons when clicked on will display detailed travel speeds and other pertinent information. That data will help drivers avoid delays and better plan their routes. And in Waze, drivers can add their own information on work zones, crashes and other incidents.

QuickMap is testing the next mobile version in which users can input their own Waze markers directly from QuickMap. It will be one more way to get real-time work zone information to the people that need it most!