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email: Traffic.dot@state.mn.us
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FAQs

Traffic Engineering Sites

Questions

 

Lighting definitions

 

2010 Lighting Design Manual

 

Minnesota Traffic Engineering Manual Chapter 10 Section 10-2.00


 

Who can help

 

How can I get a light installed at this location?

What if I have a lighting concern?


Why don't we have more roadway lighting and does Mn/DOT own all the lighting on their roadways?

 

 

Lighting specifications

 

How tall are the light poles?

How deep do the light pole foundations and piles go?

What kind of bulb and wattage does Mn/DOT use?

What kinds of fixtures does Mn/DOT use?


What manuals, standards, sample plans, specifications are available for review and guidance for roadway lighting?



Safety

 

Why is there guardrail around some poles and not others?

Why do we light the roadway?

 

New technology

What new lighting technologies are emerging?

 


 

Answers

 

Question: How can I get a light installed at this location?


Answer: Contact the Traffic Engineer (Lighting Engineer) in the appropriate District to verify that the roadway is within the State's jurisdiction and for a warrant analysis (refer to the Minnesota Traffic Engineering Manual Chapter 10 - Section 10-3.01.02). If the warrant analysis does not justify the State's participation in the light installation(s) then the local agency (county or city) may apply for a utility permit (Minnesota Permit for Working on State Right-of-Way Form 172) and install the light on State right of way.

 

 

Question: What if I have a lighting concern?

 

Answer: Contact the appropriate District to report repair needs or bulb outages (use the District's general phone number). Contact the Traffic Engineer (Lighting Engineer) in the appropriate District to report design issues such as light pollution or glare.

 

 

 

Question: Why don't we have more roadway lighting and does Mn/DOT own all the lighting on their roadways?

 

Answer: Mn/DOT needs to prioritize lighting installations considering warrants, constructions costs, maintenance costs, and utility costs. Local agencies may install lighting on Mn/DOT right of way by applying and getting approved for a utility permit.

 

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Question: How tall are the light poles?

 

Answer: Mn/DOT standard heights are 40 foot, 49 foot, 100 foot and 120 foot. Sometimes shorter heights are required to avoid penetration into airport air space.


Question: How deep do the light pole foundations and piles go?

 

Answer: Depending on the height of the pole the foundations are (steel screw in bases) 5 feet, 7 feet, (reinforced concrete) 6 feet, 9 feet, or (for the high mast lights) 6 foot T-footing with generally 3 piles at 20 feet if soil conditions are acceptable.

 

 

Question: What kind of bulb and wattage does Mn/DOT use?

 

Answer: Mn/DOT standard bulbs are 250-watt high pressure sodium (WHPS), 400 WHPS, and 1000 WHPS. Sometimes we do use Metal Halide or test new technology.

 

 

Question: What kinds of fixtures does Mn/DOT use?

Answer: Refer to the Minnesota DOT's Lighting Design Manual Chapter 3 for pictures and descriptions of the various types of fixtures. The types are listed as follow:

 

 


Question: What manuals, standards, sample plans, specifications are available for review and guidance for roadway lighting?

 

Answer: Check the Design Tools and/or the Publications for a listing of available online documents.

 

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Question: Why is there guardrail around some poles and not others?

 

Answer: Objects within a "clear zone" need to either have guardrail or be "breakaway". If there is not guardrail around an object it is either "breakaway" or outside the "clear zone."

 

 

Question: Why do we light the roadway?

 

Answer: The principal purpose of roadway lighting is to produce quick, accurate and comfortable visibility at night. The proper use of roadway lighting as an operative tool provides economic and social benefits to the public including: reduction in night accidents, aid to police protection, facilitation of traffic flow, and promotion of business and the use of public facilities during the night hours (according to the Illuminating Engineering Society (IES) of North America in Roadway Lighting RP-8-00).

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Question: What new lighting technologies are emerging?

 

Answer: Mn/DOT has been evaluating both Induction lighting and LED lighting.