North Liberty, IA
Due to the high volume of traffic during peak times of the day as well as the intersection layout and traffic control systems, motorists regularly experienced excessive delays and backup on I-380 ramp intersections with Penn Street. During peak afternoon traffic, delays could be more than four minutes. Improvements reduced this backup time to less than 30 seconds.
A Corridor Improvement Plan, including Synchro traffic modeling of the corridor, was prepared by Shive-Hattery for Penn Street from I-380 to Kansas Avenue in January 2007. This led to the design of improvements including widening two intersections; turning lane improvements and traffic signalization at two intersections.
Three signals were coordinated to provide traffic flow throughout the peak and off-peak periods of the day using wireless radio communication, a relatively new technology to the area. The wireless system eliminated the need to run a conduit under the I-380 bridge and became the first piece of the city’s long-range plan to add wireless communication for the entire city signal system.
Shive-Hattery designed these improvements and also provided construction phase services including contract administration, part-time construction observation; materials testing and construction staking. Additional services included assisting the city in applying for a $400,000 Iowa Department of Transportation U-STEP grant for construction of the improvements.
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tags: intersection, traffic signal