Evolving Drone Technology

We haven’t talked much about drones here. Our last discussion was in June of 2014. We talked in more detail in September of 2013.

Until now, drones have been more of a curiosity than anything else. But that is beginning to change. Komatsu and Caterpillar are both exploring the use of unmanned aircraft for monitoring and collecting construction data. And it was just announced that Ford and drone manufacturer DJI have teamed up to offer a $100,000 prize for the best app to rapidly deploy drones in emergency situations from Ford trucks equipped with their Sync technology. The contest started January 10th and runs through March 10th of this year. Learn more at: http://developer.dji.com/challenge2016/ .

This is a contest we should all be interested in. Assuming they do come up with a quick and easy way to deploy and recover drones from Ford pickups, it will help more than just UN relief efforts. It will almost certainly become a standard tool in our traffic operations tool box. Certainly these will be useful for major incident response.  Drones might be used to document work zone design and maintenance. And drones with longer duration flight times may one day be used to monitor traffic in real-time. Drones are rapidly evolving from “toys” into serious ITS platforms and we should all take notice.

Lane Merge Systems

Late last year the FHWA Every Day Counts initiative held another wonderful webinar. This one covered two more work zone ITS products: variable speed limit systems and dynamic lane merge systems. You can view the recorded webinar at: https://connectdot.connectsolutions.com/p1rhnco4915/?launcher=false&fcsContent=true&pbMode=normal

Last time we discussed portable variable speed limit systems. Today let’s discuss lane merge systems. Todd Peterson of FHWA began by explaining the basic structure and goals of a lane merge system and explained the differences between a late merge, early merge, and dynamic merge system.

Chris Brookes described Michigan DOT’s use of a late merge system. Their applications were last minute, high volume so a late merge made sense. He shared data showing remarkable reductions in queue length and delays. But he said there is a “steep learning curve.” When the local media supported their efforts with stories on the system, remarkable benefits were achieved. But when they did not run stories, those benefits disappeared. So drivers need to understand how the system works, what is expected of them, and why that will benefit everyone concerned.

Todd Peterson described a dynamic merge system in Maryland. There they saw high volumes during the day and low ones at night. So an adaptive system made more sense for them.

In both Michigan and Maryland they enjoyed several benefits as a result of these systems:
• Reduced speed differential between two open lanes in advance of the closure – Michigan had no recorded crashes when the system was in use.
• Reduced frustration by creating a sense of fairness.
• Reduced queue lengths – Michigan saw them go from 5 to 7 miles down to less than 2.
• Reduced delays – Maryland saw increased throughput of 9 to as much as 34%.

During this presentation two more questions were asked of the audience. They asked if their agency was considering using lane merge systems and about 70% of them are. They then asked if they were looking at early merge or late merge. 100% were considering late merge. There is no data to support this, but you’d have to suspect the interest is coming from agencies working in urban areas with high volumes and resulting capacity issues.

The data presented clearly shows remarkable benefits from late merge systems. Their low cost and ease of deployment make these an excellent tool. The Every Day Counts website includes lots of useful resources to help your agency get started using these systems. Check it out at https://www.fhwa.dot.gov/innovation/everydaycounts/edc-3/swz.cfm .

Portable Variable Speed Limit Systems

Late last year the FHWA Every Day Counts initiative held another wonderful webinar. This one covered two more work zone ITS products: variable speed limit systems and dynamic lane merge systems. This webinar was so chock full of information that I will discuss them one at a time. You can view the recorded webinar at: https://connectdot.connectsolutions.com/p1rhnco4915/?launcher=false&fcsContent=true&pbMode=normal .

Today let’s start with variable speed limit systems. Todd Peterson of FHWA began by explaining the basic structure and goals of a variable speed limit (VSL) system. These are portable, trailer-mounted signs that move as the work zone moves.

Josh Van Jura of Utah DOT described VSL experience in his state. Utah began with static (manually adjusted) signs. He says they have many interstates posted at 80 MPH. And for construction, especially where workers are exposed to traffic, they like to reduce those speeds significantly – sometimes as much as 30 MPH or more. He later said these systems are especially useful for slab replacement work where you have a relatively long work zone, but workers are present and visible only in one or two small locations. So the system gets the speeds down in advance of the work. It also drives down the speed variance.

UDOT VSL1 UDOT VSL2

So far they have chosen to use these systems where queuing is unlikely. They don’t want to solve one problem, only to cause another upstream. They have been pleased with the results and now want to move to dynamic VSL systems. They applied for and won a grant to finance their research. Kimley-Horn is doing the work.

Mr. Van Jura made an interesting point. He said that this project was especially susceptible to scope creep. As they discussed their wants and needs folks asked for CCTV, weather detection and more. Much of that was for the testing phase primarily. But even then those features would have driven the cost up significantly, so they chose to do without them.

The basic system uses sensors to measure speeds in and near the work zone. Those speeds are sent over a cellular link to a server where they are processed by an algorithm that then adjusts the posted speed limit to match the measured 85th percentile. The displayed speed limit is adjusted no more than every 10 minutes. Everything is date and time stamped showing the posted speed limit at that time at that location.

Todd Foster of VerMac asked what type of sensors they plan to use. As he said, doplar has occlusion issues but side-fire radar is a pain to set up. Josh said they plan to make that decision on a project by project basis. For two lane roads, they will use doplar. For projects on larger facilities they will weigh the need to relocate the sensors, the space available to place those sensors, and the costs associated with each to decide what should be required for that application.

A survey during the webinar asked the audience if their agency was considering using VSL systems in their work zones. 70% said yes. It then asked whether they were considering a regulatory system or an advisory system. 73.8% plan to use a regulatory system. Utah Highway Patrol cooperated fully with this UDOT initiative. Apparently other states don’t see that as an issue either.

We look forward to the final publication of Utah’s research. But it sounds like portable VSL’s should be another tool in our work zone ITS toolbox.

In our next post we will look at their discussion of lane merge systems.

Improving the Effectiveness of Smart Work Zone Technologies, Part 2

illinoisstudyIn our last post we discussed a brilliant new paper published in November by the Illinois Center for Transportation Studies. Today let’s look at their conclusions regarding work zone travel time systems. The writers point out that, “Two critical components for the success of a smart work zone deployment are the quality of the traffic data collected by sensor networks and the algorithms used for data processing.” We examined sensor types last time. Today we look at algorithms

They conclude that, “The travel time estimation is consistently poor for all algorithms and sensor networks investigated in this study. The main reason is that the instantaneous travel time calculation is a poor estimator of the true travel time in a dynamic traffic environment. In addition, the use of Bluetooth sensors can only provide the travel time of vehicles that just exited the work zone. Consequently, the travel time estimation even using Bluetooth sensors is not likely to improve the accuracy of the travel time estimates when the traffic conditions are quickly changing.”

This makes perfect sense. In a work zone you are more likely to see frequent and dynamic queuing. And that is the kryptonite for every algorithm superman. It’s too bad, because we would all like to see accurate travel time estimates, especially for work zones with significant impacts. But, ironically, it is those impacts that make estimation so difficult.

They also discussed the potential use of more advanced algorithms. This is a subject for which I have only a very limited understanding. So I am not able to examine the relative advantages and disadvantages of popular methods. But for work zones, they really aren’t practical anyway. Unless it is a very long term project, one lasting several years, the work required ahead of time to test and adjust the algorithms is expensive and still won’t make much of a difference in the travel time accuracy.

As an industry, we have worked for years to make our systems faster and easier to set up. This, to my mind, would be moving backwards. Instead, let’s work to make our travel time estimates more useful to travelers. Perhaps it makes more sense to talk about delay times. Drivers seem to expect predicted travel times to match their experience perfectly. But when it comes to delay times, they are more likely to be relieved when the delay they encounter is slightly less than predicted.

https://www.workzonesafety.org/publication/improving-the-effectiveness-of-smart-work-zone-technologies/