Evaluating a request for a new signal is a four-part process:

1. First, staff at the local MDOT Service Center (TSC) or Regional Office conduct a preliminary inquiry.
2. If the local staff decides that a signal study is warranted, the Traffic Signals staff in Lansing orders a traffic survey. A crew places counting machines around the intersection, manually counts turning volumes and gaps available in the major street's traffic stream, and observes delays that drivers experience at the intersection.
3. Next, the Traffic Signals staff analyze the survey results and the crash history of the intersection. A field review involving Traffic Signals staff and local TSC/Region traffic personnel might follow.
4. Using all the above information, MDOT issues its decision in a  formal report

This process takes anywhere from three to six months.

In evaluating the traffic information, MDOT follows federal and state guidelines called signal warrants that help engineers weigh the impact of a traffic signal on motorists. Eleven warrants are assessed when studying a location. (To learn more, see the federal Manual of Uniform Traffic Control Devices at the Federal Highways Administration site.)

Why not just install a signal when citizens request one?
A very chaotic situation would result on our roadways if signals were installed at all of the locations where requests are received. Unnecessary traffic signals can result in:

• excessive delays,
• drivers disobeying signals, or using less convenient routes in an attempt to avoid signals,
• increased crash frequency (especially rear-end type crashes).

Traffic engineershave at their disposal the data necessary to determine exactly what the problems are, along with the most appropriate solutions.