The decision to install a traffic signal is based upon an engineering study performed by a traffic engineer. A candidate intersection must meet warrants prescribed in the Minnesota Manual on Uniform Traffic Control Devices. It is important to note that traffic signals are not traffic safety devices. In fact, most serious crashes within the cities of Duluth and Hermantown occur at intersections controlled by traffic signals. Most of the time traffic signals represent the best compromise between traffic mobility and safety. St. Louis County shares ownership of approximately 40 traffic signals. Most of these traffic signals are located on the state trunk highway system. Most of the remaining traffic signals are located in the City of Duluth on the city street system. Additional resources about traffic signals can be found on the Federal Highway Administration website.

Report a Traffic Signal Outage
If you notice a traffic signal that is black (no power), flashing in an all-red state, or has indications that are not displayed (burned out), please notify St. Louis County at 218-625-3830.

Flashing Yellow Arrow
St. Louis County, along with the Minnesota Department of Transportation and City of Duluth, has been adding flashing yellow arrows to traffic signals. The flashing yellow arrow allows waiting drivers to make a left turn when there is an acceptable gap in oncoming traffic. A national study found that flashing yellow arrows reduce crashes because drivers found the flashing yellow arrow more understandable. There is also an improvement in mobility as there are more opportunities to make a left turn at a flashing yellow arrow. The following provides a basic description of each signal indication in a flashing yellow arrow signal head:

Solid red arrow
Drivers intending to make a left turn must stop and wait. Do not enter the intersections when the solid red arrow is displayed. 

Solid yellow arrow
The signal indication is about to turn to a red arrow. Prepare to stop or complete the left turn if legally inside of the intersection. 

Flashing yellow arrow
Drivers are allowed to make a left turn when there is an acceptable gap in oncoming traffic. Oncoming traffic has a green light and have the right-of-way.

Solid green arrow
Proceed with the left turn because the left turn has the right-of-way. Oncoming traffic has a red light.

Below is a video about the flashing yellow arrow:

Red Light Enforcement Lights (Blue Lights)
You may have noticed blue lights on the backside of traffic signal poles. These blue lights, also referred to as red light enforcement lights or confirmation lights, provide a tool for law enforcement to enforce red light violations. It is important to note that the blue lights are not video cameras. They are simply a blue tinted LED light that is connected into a red light electrical circuit.

The reason blue lights are being installed is to improve traffic safety. Most serious crashes within the cities of Duluth and Hermantown occur at traffic signals. Of these serious crashes at traffic signals, most are due to a driver running a red light.

Red light running cameras are illegal in the State of Minnesota. Therefore it currently requires two law enforcement officers to perform dedicated enforcement of red light running because one officer must visually confirm a red light violation and the other officer must pursue and pull over the offending driver. The blue light allows only one law enforcement officer to perform dedicated enforcement because they are positioned downstream from the traffic signal and can see the blue light. Because the blue light is connected into the red light circuit, the officer can visually confirm a red light violation. National studies have shown the red light enforcement lights have documented crash reductions between 30 percent and 47 percent. A study in Burnsville, Minnesota found a 50 percent reduction in red light violations after installation.