November 29


What to Do When You Need a Traffic Signal

By Mike Spack

November 29, 2016

city engineer, Engineers Guide to Citizen Traffic Requests, Minnesota Department of Transporation, Minnesota Manual on Uniform Traffic Control Devices, MMUTCD, MnDOT, public works, traffic signal

When I sat in the chair as a traffic engineer for the City of Maple Grove I’d get the occasional call from a resident telling me we need a traffic signal at such and such intersection. My experience is that as a resident, your best bet to get something “public works” related started is to speak with your city council person or city engineer. They are the most invested in listening to you. I work with a lot of great county and state engineers who are very responsive, but my experience has been that they dig further into requests when they officially come in from the city vs. coming from a resident. So if you are Joe Q. Public and have a traffic concern, I would call your city engineer first. They’ll know who to guide you to if they aren’t the best person to handle your call.

Now that I am a consultant, the request for a traffic signal usually comes from a property manager or developer. The conversation usually goes like this:

Hi Mike, this is Judy. I have a twenty acre parcel I am looking at developing, I have a tenant lined up (pharmacy, grocery store, big box, etc.) but they say they don’t want to build on the property unless there is a signal at the main driveway on the highway. Can you call the Minnesota Department of Transportation and get us a traffic signal approved?  And by the way – hopefully they’ll see the need and just put it in for free.

I previously wrote about Mn/DOT’s ICE Report process where they are required to look at roundabouts, all way stop signs, etc in addition to signals. In addition Minnesota Statute, via the Minnesota Manual on Uniform Traffic Control Devices (called the MMUTCD), governs the installation of signals on all public roads (as well as all other traffic devices). An engineering study per the MMUTCD needs to be done to determine if we need a traffic signal. The study involves analyzing the amount of traffic on the main street in combination with the side street. This always starts with the existing traffic volumes and may be expanded to near term future traffic volumes if a big development is imminent. My experience is that you need a big box retailer (e.g. Target, Wal-Mart, grocery store, etc.) or a several 100,000 square foot office complex to get to the minimum thresholds  (Check out our Engineering Terminology Brief) of starting to need a traffic signal, but it is very situational. You won’t meet the minimum thresholds with just a restaurant, strip center, or pharmacy alone.

Most counties as well as Minnesota Department of Transportation push back very hard about putting in traffic signals unless there is heavy traffic throughout the day. These jurisdictions have a backlog of locations where they would like to put in traffic signals, but don’t have the funds to build them (the last I heard, Hennepin County Minnesota has a backlog of 100+ intersections and they build about two a year with their own funds). On top of this, it is proven that crashes go up when a traffic signal is put in vs. just stop signs on the side street (rear end crashes go up significantly, but hopefully severe crashes go down). So signals aren’t a pure silver bullet.

So if you are a property manager or a developer, here is the process I recommend (which isn’t that much different from what a resident should do):

  1. Prepare a Study. Get a reputable traffic engineer to do the appropriate engineering study (as step one you can see if the city will do the study for you, but they will typically ask you to prepare the study).
  2. Share Your Study with the City. Bring the study to the city (preferably starting with the city engineer) to get their support.
  3. Get County / State Agency Support. Have the city lobby the appropriate county/state agencies. Typically signals are needed at a driveway or city street intersection that intersects a county or state highway – so you need the other agency’s permission as well as the cities.
  4. Prepare to Negotiate. Lastly, if the signal is needed for YOUR property, the public agencies are going to expect you to pay for part/all of it.  Of course, this is a negotiation – where the public agencies hold the trump cards!

Finally, if you are like many agencies that get requests from the public for various traffic control measure, you may find our Engineer’s Guide to Citizen Traffic Requests a useful tool. Take a minute to check it out.

  • I didn’t know a lot of things needs to be done before a signal can be built. I also agree that putting a traffic signal on an intersection depends on the surrounding buildings and what they are and the amount of traffic are in the intersection. Itcmay be a better solution to have a stop sign for an intersection rather than a traffic signal. Each case is different, but o didn’t know that private property owners may have to pay for the traffic signals. I thought all of these projects are funded by the government.

  • Speaking of traffic signals. Is there anything against not having an engineer design one? Whether it is a new one or change from an existing installation. I have heard that this could possibly be criminal action for ‘practicing engineering without a liciense’?

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    Mike Spack

    My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

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