a heart with a twist of lemon

just in case anyone else had this burning question about stoplights inside like i did. i contacted MN/dot and got some answers, and now i am just passing on my knowledge, because KNOWLEDGE IS POWER!

David wrote:

This is kind of a random question but how are the stoplights timed? Are there scales that let them know when cars are waiting? Just something I was wondering about.

Thanks,
David Mackereth

and Jerry answered:

David,
Traffic signals are timed by various factors such as posted speeds and approach volumes, to name a few. The most common type of traffic detection that MN/DOT uses is an 6'x6' inductive wire loop placed in the roadway. This type of loop will sense the change in inductance when a vehicle drives over it. There are other types of detection such as camera, sonic, magnetic and acoustic that are less frequently used. Our web site has FAQ's that you may be interested in. The site is: http://www.dot.state.mn.us/trafficeng/faq/index.html
Hope this helps,

Jerry Kotzenmacher
Traffic Systems Specialist
MN/DOT - Office of Traffic, Security & Operations
Office: 651-284-3438
Cell: 612-202-6802