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Commonly asked MDOT questions

This list of commonly asked questions at MDOT has been developed from web inquiries and/or phone calls and may not cover every topic or concern. Popular topics, our frequently asked questions page, and the website search are also great resources when looking for information.

  • When driving by a work zone, that’s just a snapshot of work that’s going on at that particular construction site. Lane closures are put in place for many reasons, including giving workers a buffer to work safely, to keep motorists safe when nearby excavation or removal of guardrail has changed the roadway characteristics, or for the removal or addition of materials. Sometimes the pavement in a closed lane looks intact but adjacent material removals may make it unsafe to open the lane to traffic. In other cases, the closed lane has curing concrete that may take days to reach the proper strength to reopen to traffic. Whatever the reason, MDOT works to keep as many lanes open to traffic as possible when it can be done safely.

  • Not all work zones are set up as zipper merges. When they are, the signs are very clear and specific. It’s not always the preferred method but they can be very effective when drivers read the signs, cooperate and are courteous to other motorists. Drivers should never block lanes or try to control traffic. It’s dangerous, illegal and accomplishes nothing.

    Zipper merge work zone signs are quite clear: Drivers should use both lanes and take turns at the clearly signed merge point.

    Work zones in general are dynamic and change throughout the day based on traffic volumes. When traffic is light, vehicles can get to the open lane without issue. But when things get congested and jam up, zipper merges are effective in reducing backups. Instead of 1,000 cars in one lane you’ve got 500 cars in each lane. This prevents backups to adjacent interchanges and curves that might reduce line of sight. Plus, when drivers take turns at the merge point, it takes all the guesswork out and creates a safer, better flow of traffic within the lane closure.

    MDOT has participated in news stories to educate and promote zipper merging and we will continue to do so. 

  • 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.

  • 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. 

  • Unfortunately, on heavy traffic days, conditions at a rest area can get poor pretty quickly. Our staff does check our rest areas more frequently during high-traffic periods but it also doesn’t take very long before conditions can degrade when they are busy. For example, one tour bus or two can result in some messy conditions and overflowing trash cans pretty quickly. It’s unfortunate that some visitors aren’t respectful of their fellow travelers but our staff address those issues as soon as they can. Given our funding constraints, we can’t have people there around the clock.

    We’ll keep doing the best we can to keep our rest areas as clean as possible and put our best foot forward for visitors.

  • 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. 

  • We certainly understand that it is both unfortunate that animals are sometimes killed by passing vehicles and that their carcasses are unpleasant to see.

    We do have our contract maintenance agencies and our own maintenance employees move roadkill off the roadway for safety but do not always remove the carcasses in rural areas. This work is done alongside their other duties, and as they become aware of the carcasses, it often does take some time for removal to occur.

  • A separate green left-turn arrow signal phase does make sense in some locations when traffic volumes meet traffic signal warrants (covered in Chapter 4C: Traffic Control Signal Needs Studies of the Federal Highway Administration (FHWA) Manual on Uniform Traffic Control Devices (MUTCD), page 651). Installing a left-turn signal phase usually involves upgrading the traffic signal. If there is insufficient turning traffic, a dedicated left-turn phase sometimes means greater delay for other drivers. MDOT does routinely review traffic volumes and delays at its signalized intersections and can add left-turn phasing when warranted. 

  • MDOT does coordinate work with other road agencies but we’re all working with the same seasonal constraints for road work and sometimes work on adjacent routes must be done at the same time. Whenever possible, we’ll avoid working on interdependent routes but sometimes it is unavoidable. 

  • MDOT has jurisdiction over state highways in Michigan, which are I, M and US in Michigan; those highways may also have local names, like US-24 (Telegraph Road) and M-1 (Woodward Avenue). What you are referring to, a concern about how a local road under local jurisdiction is maintained, is not in MDOT’s jurisdiction. MDOT cannot compel the road commission or local road agency to make upgrades to your road. 

    If you live in a township, you can find the contact information for your county road commission by visiting www.micountyroads.org/about/find-a-county-road-agency/.

    If you live in a village or city, you’ll need to reach out your local governmental agency.

    In cases where local units of government receive federal or state funding for a construction project, MDOT is tasked with ensuring those construction projects meet federal and state requirements.

  • Yes, all work in state highway right of way, including driveways, requires an MDOT permit. All construction permit applications are submitted and purchased through the MDOT Permit Gateway online service. Learn more about the construction permit process or contact your local area permit coordinator.

  • Due to funding constraints and many other maintenance needs, MDOT does not mow expressway medians regularly but rather on a rotating schedule when resources allow. In some cases, medians are left unmowed for wildflowers and, occasionally, planted sunflowers. Snowplowing is also part of the same maintenance budget as mowing, so that means if it's been a rather harsh winter that required more plowing and salt usage, then that puts even further stress on mowing and other summer maintenance.

  • MDOT does not prohibit parking on the side of state highways with narrow exceptions. Parking on roadsides is important for drivers who need to pull off the roadway for emergencies. Law enforcement lacks sufficient resources to police “no-parking” areas and a prohibition on parking in a particular location does not address the root cause of the parking issue. We would suggest you share your concerns with your local unit of government. If they feel this is a recurring issue and they would like it signed as "no parking," they can contact your local MDOT Transportation Service Center (TSC). At that point, we can consult with Michigan State Police (MSP) to see if they would concur on a traffic control order, and we could place “No Parking” signs.

  • 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.
    Refer to MDOT’s roundabouts web page for more information: www.Michigan.gov/Roundabout.
  • 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.

  • MDOT repairs potholes as quickly as possible. While our direct and contract maintenance forces do patrol for them, particularly in the spring, potholes can form quickly, sometimes in a matter of only minutes.

    Motorists can report potholes online directly to maintenance forces for the quickest response.

    Motorists also are able to attempt to recover the cost of repairing damage caused by a pothole on a state highway (I, M or US-route) by filing a damage claim

  • During the day, that traffic sign may look fine but at night it may not be visible enough for drivers to see and understand its message. Retroreflective signs are especially beneficial to older drivers. By 2030, one in five drivers will be age 65 or older. A 65-year-old's eyes need eight times the amount of light a 25-year-old's does. Bright, highly reflective traffic signs are more visible at night and can reduce nighttime crashes by helping older drivers (and motorists of all ages) to quickly read and react to commands and information on the signs. The reason why we replace traffic signs and their supports is further explained online at MDOT’s Traffic Signing Program: Why Traffic Signs Are Replaced.

  • It isn’t legally possible for MDOT to prohibit legal road users (including semis) from using our state highways. Some routes are certainly preferrable: they are part of the National Truck Network, recognized as a high-volume route utilized extensively by large vehicles for interstate commerce.

    Trucks aren’t able to evade legal weight enforcement simply by taking different routes. MDOT partners with the Michigan State Police (MSP) Commercial Vehicle Enforcement Division to identify critical weigh enforcement infrastructure along MDOT highways. Although truck weigh stations are essential for monitoring and enforcing weight restrictions, MDOT and MSP also maintain additional infrastructure to assist in enforcing overweight vehicles. Weigh-in-motion sensors (WIMS) scales beneath the road surface detect overweight vehicles and permanent intermittent weigh scales (PITWS) facilities located along MDOT highways where MSP can legally weigh trucks. WIMS and PITWS function together as an enforcement tool and are strategically located to monitor the MDOT highway network. We can reach out to our partners at MSP to look at increasing commercial vehicle enforcement in specific areas.

  • As engine brakes or “jake brakes” are legal equipment in Michigan, MDOT will not install signs prohibiting their use. The Michigan Vehicle Code does address exhaust noise, which is not an engine brake but is related to vehicle condition. Furthermore, police cannot enforce engine brake use because it is not in violation of state law. It is almost impossible for an officer to prove in court that a driver was using his brakes and not simply letting off the accelerator. Putting up signs does not always address the situation of enforcement if it is not possible. A local noise ordinance may be enforceable. MDOT does allow local agencies to install “noise ordinance strictly enforced” signs at their own expense via permit, with a requirement that there be proof of enforcement, or the signs will be removed.