Ellen Huber: Exploring the reasoning behind traffic signals
From time to time, the city of Mandan receives inquiries about new traffic control signals. Intersections where business owners and the public indicate interest in having more traffic controls include Memorial Highway at 40th Avenue S.E. and Third Street S.E., additional Main Street locations, Sixth Avenue S.E. and Burlington Street S.E., and Sunset Avenue and Boundary Road.
The decision on whether or not to install a signal is not just up to city officials. Mandan has urban arterial and collector streets that are part of the North Dakota Department of Transportation Urban Roads System. The roads identified in this system receive the scrutiny of NDDOT and the Federal Highway Administration when it come to maintenance and reconstruction projects as well as safety concerns of those roadways.
Before a new traffic signal can be constructed, the FHWA Manual on Uniform Traffic Control Devices requires an engineering study of traffic conditions, pedestrian characteristics, and physical characteristics of the location. The study examines if the traffic signal is justified and if it will improve the overall situation. The minimum guidelines, referred to as warrants, are based on:
• Eight-hour vehicular volume
• Four-hour vehicular volume
• Peak hour vehicular volume
• Pedestrian volume
• School crossing
• Coordinated signal system
• Crash experience
• Roadway network
• Intersection near a grade crossing
Meeting one of these warrants does not necessarily mean a signal will be constructed. Traffic signals may resolve some problems, while creating others. All impacts are considered.
The N.D. Department of Transportation tells us that the Mandan intersections previously mentioned do not currently meet warrants for traffic controls. As our community grows and traffic volumes increase, this may change.
Planning for the reconstruction of Memorial Highway is taking into consideration that conditions may meet warrants for traffic signals by the time it is reconstructed, likely to be 2016 or beyond.
Traffic signals are expensive and costs can vary depending on if other changes are needed at an intersection. For example, new traffic signals installed last August at the intersection of Sunset Avenue and Old Red Trail cost approximately $200,000, without the expense of work to the roadway itself. All of the city of Mandan’s traffic signal projects have been a part of the urban roads system and therefore qualify for 80 percent federal cost participation.
As citizens, drivers, shoppers or business owners and managers, we may not like the answers we receive regarding traffic signals. After all, we want signals and we want them now. Hopefully this article at least provides insight into how the process works. For more information on roads or questions regarding traffic flow, contact the city of Mandan Engineering and Planning Office at 667-3225.