A Chicagoland First: Flashing Yellow Arrow Turn Signals
Motorists will see something new as they venture west from Chicago to the Fox Valley suburbs. In 2015, Kane County became the first agency in northern Illinois to install flashing yellow arrow signals for conveying permissive left turns.
“National safety data shows that flashing yellow arrows are more intuitive, signaling to motorists the need to yield to both oncoming traffic and pedestrians that may be crossing in the path of a left-hand turn,” said Kane County Department of Transportation Traffic Engineer Stephen Zulkowski, P.E.
The signals are part of an improvement to Randall Road between Silver Glen Road on the south side of the village of South Elgin and Fabyan Parkway on the south side of the city of Geneva. The road covers a mix of residential and commercial neighborhoods, as well as Delnor Community Hospital.
A federal grant covered 90 percent of the safety upgrade costs. The project is scheduled for completion by the end of the 2016 construction season. The Highway Safety Improvement Program (HSIP) project includes installation of the new signals, as well changes to the signal head placement on new poles, and driver feedback speed limit signs.
“We’ve already calculated, as part of the HSIP application, that these changes will provide a large improvement to driver safety, ensuring that the use of these federal funds will give us the most benefit across a large section of Kane County,” said Zulkowski.
Thorne Electric served as contractor for the project. MoboTrex supplied the signals and brackets, poles, pedestrian heads and latching buttons, and malfunction monitoring units. They also supplied on-site field technicians to support those products and to reconfigure or modify the traffic cabinets and controllers as needed for signal functionality. The technicians were available from the time the intersections went to flash or dark, until they were again in colors.
Preparation is Key
Considerable planning for what’s above and below ground was necessary. “While we needed to plan and adjust during the implementation phase, I would encourage others to think about this during the design phase too,” said Zulkowski.
Because the HSIP included one signal traffic head per travel or turn lane, the DOT installed new concrete and signal poles.
The DOT chose to proceed without installing temporary signal poles, using the existing equipment during the transition. This decision required that everyone involved choreograph their responsibilities so that the signals were usable during the morning and evening rush hours. They pushed new wiring through existing underground conduit and pushed new conduits in places with insufficient cable capacity.
“It would certainly be easier to install temporary signal poles. The primary reason to do this is to allow you to completely clean out any old wire or debris in the underground conduit without impacting signal operation but these temporary signals come as an added cost to a project,” said Zulkowski. “In our case, we had engineers confirm there was enough room to push new wire. However, field conditions proved to provide less usable capacity than calculated in design –additional conduits was our solution but a temporary signal would have also been a good idea.”
Other elements considered included available load switches, and what was controlled including pedestrian crosswalk and right-turn overlaps in all directions. Also, a four-channel emergency-vehicle preemption system was in place. MoboTrex tweaked the signal controller and conflict monitor to ensure all devices worked with that system.
A Six-hour Modification Window
With several signal installations complete, Thorne Electric Superintendent Kenny Thorne says preparation and day-of-modification processes worked well. The actual modification window was only six hours.
“We were fortunate that the DOT closed the side streets so that traffic flowed north and south uninterrupted and we did not have to work around traffic on four corners,” Thorne said. “Because we had already performed some of the work ahead of time, my group spent several hours getting things into position then the MoboTrex crew had one to one-and-a-half hours to program. We then quickly moved into conflict testing. Everything was up and running by 3 p.m.”
Thorne performed a lot of time-saving preparations ahead of time. Signal heads were mounted earlier, requiring that only the fifth section be removed during cutover. Areas that needed new conduit were also pushed early. “This project challenged us to a new way of thinking and organizing ourselves,” said Thorne.
Working in tandem with the Kane County Board, the Department of Transportation reached out to local agencies in the cities of Geneva, St. Charles and South Elgin to help educate motorists about the changes. The County empowered the cities to hold community information meetings supplemented with web-based education tools and messages made available on the County’s web site.
“From the county, state, and federal highway perspective, it will take several years to understand just how much of a safety improvement we will realize. We’re always tracking crash data and future statistics will demonstrate the impacts of this improvement. Based on other region’s experiences, we feel the data is certainly encouraging,” said Zulkowski.[Download not found]