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Traffic Signals
Traffic Signals

The Ohio Department of Transportation is responsible for the proper design, installation, maintenance, and operation of traffic signals along state, federal, and intestate highways. The agency works to ensure that existing traffic signals are timed to allow the most efficient traffic flow possible, and that new traffic signals are installed only when justified.

While many believe that traffic signals are the answer to all traffic problems at intersections, an unwarranted traffic signal can result in increased delay, congestion and accidents. Traffic signals should be installed only when they will alleviate more problems than they will create.

Who's responsible for which signals?


Generally, the Ohio Department of Transportation (ODOT) holds jurisdiction and responsibility for interstate routes, federal, and state routes outside of municipalities. Cities, villages, counties, and townships maintain and construct their own roadways, while the Ohio Turnpike Commission is responsible for the maintenance of the Ohio Turnpike.

The above jurisdiction applies to traffic signals. ODOT maintains the signals along state and federal routes outside of municipalities, even if the signal is located at a state or federal highway's intersection with a local roadway. ODOT also maintains the signals at all interstate interchanges.

Traffic signal guides, manuals, and training

Do you work for or with ODOT to install, operate and maintain traffic signals? Visit the page below for some helpful links to the Signal Design Reference Packet, warrant spreadsheet, guides, and programs. 

Traffic Signal Resources

How do I request a signal?

The first step in getting a traffic signal installed is to determine the governmental agency that has jurisdiction for the intersection and contact that agency. If the Ohio Department of Transportation (ODOT) has jurisdiction, then contact your local district office with your request.

The district office will perform a warrant analysis, based on warrants listed in Section 4C of the Ohio Manual of Uniform Control Devices (OMUTCD). If the intersection meets the warrants, a sound engineering judgement will be made to determine if the intersection should be signalized. A traffic light is not always the best solution to improve an intersection. See "advantages and disadvantages of traffic signals" below for more information.

In accordance with the Ohio Revised Code (ORC), ODOT can install and operate traffic signals only at public streets. If a private development warrants a traffic signal, the property owner must enter into an agreement with ODOT, pay for the installation of the traffic signal, and pay an annual signal maintenance and operation fee.

For information on timing analysis requests for existing traffic signals, see the Statewide Signal Timing & Phasing Program (SSTPP).

Advantages and disadvantages of traffic signals

A traffic signal is not always the best solution to improve an intersection. While traffic signals can help in locations where they are justified and installed properly, even justified signals can have its disadvantages. It's important to understand why traffic signals are (or are not) installed.

The following advantages and disadvantages are outlined in Section 4B.03 of the Ohio Manual of Uniform Traffic Control Devices (OMUTCD). 


  • They provide for the orderly movement of traffic.
  • They increase the traffic-handling capacity of the intersection if:
    • Proper physical layouts and control measures are used, and
    • The signal operational parameters are reviewed and updated on a regular basis to maximize the ability of the traffic control signal to satisfy current traffic demands. 
  • They reduce the frequency and severity of certain types of crashes, especially right-angle collisions. 
  • They are coordinated to provide for continuous or nearly continuous movement of traffic at a definite speed along a given route under favorable conditions. 
  • They are used to interrupt heavy traffic at intervals to permit other traffic, vehicular or pedestrian, to cross. 


  • They can cause excessive delay.
  • Excessive disobedience of the signal indications may occur.
  • They can increase use of less adequate routes as road users attempt to avoid the traffic control signals.
  • They can cause significant increases in the frequency of collisions, especially rear-end collisions.

Additional FAQs

Why are 'Prepare to Stop When Flashing' signs being removed?

The Ohio Department of Transportation is reviewing the statewide use of “Prepare to Stop When Flashing” signs, which were historically used to alert drivers that a signal is turning red. The signs are being replaced with new technology that can detect the speed of approaching vehicles and adjust the signal to prevent red-light running and crashes.

A statewide review of the signs found that drivers often speed up instead of slowing down upon seeing the flashing sign, increasing the number and severity of crashes at intersections.

ODOT has seen a significant reduction in crashes at 14 intersections where the signs were removed within the past two years.  The average crash reductions included a 23% reduction in total crashes; 35% reduction in serious crashes; 42% reduction in angle crashes; and 50% reduction in red-light running crashes.

Many states are reexamining the practice of using the warning signs, which were often installed at isolated intersections where motorists are traveling at high speeds and not expecting to stop.  They are also used at locations where signals are difficult to see because of geography.

Many of the signs will be replaced with new, safer technology called dilemma zone detectors.  These detectors use radar technology to monitor the speed of approaching vehicles and extend the signal green time if a motorist cannot safely stop for the red light. This time‐based system tracks vehicle location, speed and arrival time to the stop line. This information can be communicated to the traffic signal controller and the extended green can be displayed more accurately, thus further minimizing dilemma zone conflicts and increasing efficiency. 

ODOT is also adding florescent yellow borders to many signals to improve visibility at night and longer distances.

However, not every warning sign will be removed.  Each location will be evaluated, and some signs may be retained, especially in areas where geography makes it difficult to see the signals at a distance.

Why do traffic signals sometimes flash red in all directions?

Prior to the 2000s and the installation of LED signal lamps, it was common practice for agencies to use off-peak flashing operation to save energy costs and eliminate delay.

Multiple nationwide studies have been conducted that prove with the elimination of off-peak flash the following significant safety benefits were gained, according to a study by the Federal Highway Administration:

  • 48% reduction in all crash types.
  • 53% reduction in injury and fatal crashes.
  • 57% reduction in all frontal impact crashes.

The Traffic Engineering Manual (TEM) 403-3 was updated in January 2017 to eliminate language allowing ODOT owned and maintained traffic signals to use yellow and red (Y+R) flash. As a signal in flash is a temporary condition caused by a malfunction, all-red flash shall be used.

Safety is the guiding principle behind the all-red flash, as crash numbers and supporting evidence prove that Y+R flash leads to driver confusion and the potential for serious crashes.

What are the requirements for a multi-way stop installation at an intersection?

As noted in Section 2B.07 of the Ohio Manual of Uniform Traffic Control Devices (OMUTCD), a multi-way stop control can be useful as a safety measure at intersections if certain traffic conditions exist. Safety concerns associated with multi-way stops include pedestrians, bicyclists, and all road users expecting other road users to stop. Multi-way stop control is used where the volume of traffic on the intersecting roads is approximately equal.

Generally, multi-way stop installations should be used sparingly because of the significant increases in delays and operating costs that can result from requiring all of the vehicles using the intersection to stop. Also, unnecessary stops, when the intersection is clear of conflicting movements, can lead to general disrespect for stop signs.

Any decision to install multi-way stop control should be based on an engineering study. OMUTCD Section 2B.05 addresses restrictions on the use of stop signs that also apply to multi-way stop applications. Section 2B.07 of the manual contains criteria that should be considered as part of the engineering study