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Speed limits in Michigan are set in accordance with state law, which requires that they be posted at the speed at which 85 percent of vehicles are traveling at or below, commonly referred to as the 85th percentile speed. So, if 100 cars travel through an area, 85 of them are going at or below that speed. On state highways, setting speed limits is a joint process between MDOT and the Michigan State Police (MSP), and the two agencies conduct speed studies that determine the 85th percentile speeds. Neither agency can arbitrarily lower speed limits.

If your community feels the current speed limit in that area is too high, the township board can request that MDOT and MSP conduct a speed study. The board would need to pass a resolution requesting the speed study and agree to honor the results. That’s important because if a speed study reveals that the 85th percentile speed on a corridor is actually higher than the current posted speed limit, state law requires MDOT and MSP to raise the speed limit in accordance with state law. State law does not allow posting speed limits below the 50th percentile speed.

Traffic signals are primarily installed to improve the efficiency of an intersection. Depending on the crash types, a signal may not address the concern and could inadvertently lead to more crashes.

Before determining whether or not a traffic signal is appropriate for a given intersection, MDOT must first perform a signal study and see if the location meets one or more of nine signal “warrants,” or conditions that must be met before a signal will be installed. Warrants include eight- and four-hour vehicle volumes, peak-hour volumes, pedestrian volumes, presence of a school crossing, presence of a coordinated signal system, crash experience, nearby roadway network traffic flow, and presence of a nearby at-grade railroad crossing. MDOT does not install traffic signals at locations that do not meet any of these warrants, as that may inadvertently increase the number or severity of crashes. 

MDOT does have rules for posting temporary political signs along state highways. These rules apply to state highways only; local road agencies and municipalities may have their own rules. Generally speaking, our two biggest concerns are with safety and potential for littering. Signs are never allowed in locations where they impede drivers’ vision, or of a size and design that would pose a hazard if they were struck. Additionally, signs need to be removed within 10 days following elections so that they don’t become roadside litter or inhibit maintenance activities. We don’t police signs based on content; we are focused on safety and littering. We post our rules expecting that most people will voluntarily comply. 

MDOT builds roundabout for several reasons, including:

• Safety: Roundabouts reduce vehicles speeds, as well as the number of conflict points. Roundabouts reduce head-on/left-turn and angle-type crashes that frequently result in serious or fatal injuries.
• Operations: With the use of yield signs instead of stop signs or traffic signals, vehicles can enter the roundabout when there are adequate gaps in the traffic flow. This reduces the number of vehicles that must stop and reduces the time vehicles are stopped. This reduces delay and increases the capacity of the intersection.
• Maintenance: Roundabouts reduce long-term operational and maintenance costs associated with traditional signalized intersections. There are no traffic signals to power and maintain, which can amount to a savings of about $5,000 per year.
• Aesthetics: Roundabouts create an area for community green space and landscape architecture. There are no large poles, overhead wires or signals to clutter the visual environment.

Lane reconfigurations, or road diets, can help improve safety for all roadway users by encouraging drivers to reduce speeds, removing congestion and reducing crashes related to left-turning vehicles by providing a center left-turn lane and providing space for other amenities, such as trails or sidewalks, wider shoulders, bike lanes, on-street parking, or bus stop pull-offs. When properly placed, lane reconfigurations provide all of those improvements without significant delays or additional travel times.

The Federal Highway Administration (FHWA) has more information on road diets/roadway reconfiguration on its website.