Let there be lights!
By Doug Lindner
SOLON– The City of Solon got something it had wanted for a long time, and right before Christmas, too.
The possibility of a traffic light to stop vehicles on Highway 1 at one of Solon’s busiest intersections.
During the Dec. 4 meeting of the Solon City Council, representatives from the Metropolitan Planning Organization of Johnson County (MPOJC) delivered a transportation study showing that both the Main Street and 5th Street crossings of Highway 1 now qualify under federal guidelines for a traffic signal. MPOJC recommended the Main Street intersection be given first consideration.
The city had asked the regional planning group to undertake a traffic signal warrant study for both intersections of Highway 1, as well as identify possible access points on the highway north of current development.
The MPOJC also inventoried the city’s sidewalks, reviewed possible trail connections and summarized traffic on city streets.
But the news that both intersections could qualify for signalization was most significant for the city, which sees the need to establish a controlled route of travel from one side of the highway to the other.
A traffic signal warrant study examines the levels of nine criteria which could prompt the need for a signal. In Solon’s case, only four of the criteria were deemed relevant for the intersection and included in the report. At a minimum, one of the areas must be at the triggering level where a signal would be warranted. But the satisfaction of a warrant does not in itself require the installation of a signal.
A similar report done for 5th Street in 2012 showed that traffic volumes were close to triggering one of the warrants.
A year later, both intersections triggered warrants.
According to assistant transportation planner Kent Ralston, Main Street triggered two– peak hour traffic and four-hour vehicular volume.
“Even though a signal is warranted, a signal is not always a great option at an intersection,” Ralston explained. He said the MPOJC uses software to analyze the data and project the delay per vehicle in seconds, applying a letter grade to the flow of traffic.
In Solon’s case, he said, a signal would benefit the Main Street intersection.
Citing a section of the report, Ralston said the grade letter for westbound traffic improved from a grade of D and E to an A with signalization. Higher-volume traffic on Highway 1 would be delayed mere seconds, lowering the grade from an unobstructed A to a B.
“There’s really not much of a change there,” Ralston said. “You wouldn’t be introducing a whole lot of delay (to Highway 1) as the software showed it.”
So where does the city go from here?
The highway is the jurisdiction of the Iowa Department of Transportation (DOT), Ralston said, and there is a permitting process for a signal request.
According to MPOJC Executive Director John Yapp, there are some competitive DOT funding sources the city might be able to utilize to offset the ballpark $200,000 cost of a signalized intersection. The city is also expected to place the traffic lights on its Capital Improvement Projects (CIP) list.
The Main Street signal is being recommended by MPOJC because Main carries a higher volume of traffic than 5th Street, has visibility issues and is the gateway to the community’s commercial district, Yapp said.
“The other benefit of a signal to the larger corridor is that it helps create gaps in traffic,” he added.
Solon’s most common collisions on the highway are broadside, considered more dangerous than rear-end accidents and also more correctable. The gaps created by a signal provide space for vehicles to safely cross or join up and down the highway, Yapp said.
More accidents occurred at 5th Street, he said, which prompted a discussion among staff members about which intersection to address. But Main Street had higher pedestrian numbers, as well as the downtown businesses and visibility problems, he said.