820 - Traffic Signals

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Traffic Signals
Traffic Signal


LED Traffic Signals

Adaptive Signal Control Technology


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Traffic Signal Installation, Steel Strain Pole Band Clamps

Steel band clamps are used for traffic signal span wire installation on steel strain poles. Clamps must meet the material requirements in Special Detail SIG-010-A “Span Wire T.S. on Steel and Wood Poles”, Detail B, Pole Band Clamps on Steel Pole”, which specifies ASTM A36 steel bands using ASTM A325 galvanized steel bolts.

Pole band clamps must be stamped with identification that is traceable back to the manufacturer, which can be used to determine the month and year of clamp manufacture. The stamping method must be a low stress stamping method. The stamp cannot be located near the bolted flange, must be located near the center of the backside clamp from traffic on the outside face, and be visible after galvanizing. Any questions regarding clamp identification can be directed to the Traffic Signals Unit at 517-322-3360.

The minimum inside bend radius for cold formed members must be at least 1.5 times the material thickness (or 3/8 inches).

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Notification of Traffic Signal Work

It is the contractor's responsibility to notify MDOT’s Statewide Signal Shop prior to beginning any signal work. Traffic signal projects include a note in the project plans that state the following, "Contact MDOT (and any other maintaining agency) seven (7) working days prior to start of construction and seven (7) working days prior to signal activation.” Appropriate contact information is indicated in the plan notes. The seven day time frame will allow for coordination between the contractor and the Statewide Signal Shop for installation and inspection of traffic signal work. It is recommended that these notification requirements be discussed at the pre-construction meeting.

The Statewide Signal Inspector must be on-site to help to ensure that unsafe conditions with the traffic signals are not utilized or incorporated into the project work and to protect the safety of the public. Any work done incorrectly will need to be corrected at the contractor's expense.

If an inspector from MDOT’s Statewide Signal Shop or appropriate maintaining agency is not on site when a contractor is performing signal work, the project representative (MDOT/consultant engineer or inspector) should stop the signal work until verification of prior notice to MDOT has been confirmed. Construction staff should call the Statewide Signal Shop at 517-322-3360 to verify whether inspection notification requirements have been met. If prior notification was not provided by the contractor, form 1165, Notice of Non-Compliance with Contract Requirements is to be issued until the contractor properly notifies the Statewide Signal Shop and necessary inspection arrangements have been made.

To ensure proper coverage and discussion Jim Kwapiszewski, should be invited to preconstruction meetings for projects that involve any traffic signal work.

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Traffic Signal Pole Locations

The American with Disabilities Act (ADA) requires pedestrian pushbuttons be placed strategically to provide accessibility for any person with disabilities. There are mandatory distances for placement of pushbuttons in conjunction with crosswalks. Also, there are traffic signal timing implications for placement of the pushbuttons. Traffic signal installations are designed to specifically accommodate those requirements. Traffic signal pushbuttons can be placed on isolated pedestals or in combination with traffic signal support poles. When a designed pole location is relocated without knowledge or approval of the Traffic Signals Unit, it could result in a violation of the ADA requirements and open the department to litigation. Do not approve changes to traffic signal operations without knowledge or approval of the Traffic Signals Unit. Changes of this nature can have implications to ADA requirements.

When it becomes apparent that a designed signal pole location is not feasible, or a request for a change in operation has come from outside the Traffic Signals Unit, construction staff must contact the Traffic Signals Unit in Lansing. The Traffic Signals Unit will assist in determining where to move the pole, along with any changes made to the signal operation, while maintaining compliance with ADA requirements.

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Traffic Actuation of Temporary Traffic Signals

When using trailer mounted temporary traffic signals on projects, review each site to determine if the temporary traffic signals should be required to be retrofit for traffic actuation.

Temporary traffic signals should be retrofit for actualization when any one or more of the following conditions exist on the project site:

  1. Traffic volumes that are low enough to create time periods when a vehicle would be held on a normally timed red signal where no opposing traffic is present.
  2. Traffic volumes that are directional, where directional traffic may be stopped on a red indication before the entire queue can clear the signal.

Construction staff should work with region/TSC traffic and safety staff to determine if the temporary traffic signal location should be considered for actuation.

If it is determined the temporary traffic signal meets the requirements to be retrofit, advise the contractor of the required additions to the temporary traffic signal, and pay for the retrofit as a contract extra work item with a negotiated extra cost.

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There are several types of inspections depending on the circumstance of the signal contract. These inspections follow those typically performed for Road, Bridge and Ancillary Structures inspections. The Michigan Ancillary Structures Inspection Manual (MiASIM) outlines procedures for performing in-service inspections of ancillary structures including steel strain poles and mast arms.

Initial Inspection

This inspection should be performed shortly after an asset is constructed or installed. Please reference Section 810 for initial asset inspection procedures of mast arms and steel strain poles.

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Acceptance of Traffic Signal Work

An inspection work authorization (IWA) will be issued by the signals unit for all projects that contain traffic signal pay items. If the project engineer has not received a copy of the IWA by the time of the preconstruction meeting, please contact the signals unit to expedite the IWA. The agency listed first on the IWA will be responsible to determine suitability and compliance with specifications for the signal items. This agency must provide the project engineer with a memo or other documented acceptance of the signal work items prior to proceeding to the Final Inspection of the project by the construction/project engineer.

Full payment for completed traffic signal work is to be made after the Engineer’s inspection staff inspect the work for contract compliance and work is reported on an IDR. Final inspection and acceptance of all contract work (form 1120) is not to occur until the maintaining agency documented acceptance is received. A sample memorandum is provided below, and a blank form is available by clicking on the sample image:

CL 09032-01-002 - sample.jpg

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