Showing Tag: "detection" (Show all posts)

Bicycle Detection at Traffic Signals

Posted by Steve Fitzsimons on Wednesday, January 22, 2020, In : For Traffic Signal Designers 
As a frequent bicyclists, one of my regular frustrations is the inadequate bicycle detection.  The industry guidelines suggest a single 6-foot long detection zone at the stop bar in a bike lane or in vehicle lanes is adequate.  However, when I am on my bike, approaching an intersection with one or two vehicles waiting, and see the light go green, I often groan because I can see the green light will not last long enough for me to make it.  I am left with the choice of pumping really hard to tr...
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Cutting Traffic Loops

Posted by Steve Fitzsimons on Monday, October 15, 2012, In : For Traffic Signal Designers 
Question:  How are detector loops installed?
Answer:  There is a variety of equipment.  The photo below shows a round loop saw (Caltrans Type E).  The second photo shows a saw that cuts straight lines.  This saw can be used in combination with the previous to cut the lead in slots or can be used by itself to make a square loop (Caltrans Type A or D).  It takes about 5 minutes to cut a Type E loop, 10 minutes to cut a Type A loop, and 15 minutes to cut a Type E loop.  The cutters have a jet of ...
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New Bicycle Standards

Posted by Steve Fitzsimons on Thursday, December 3, 2009, In : For Traffic Signal Designers 

Question:  I’ve been told Caltrans recently issued new guidelines on accommodating bicycles at signalized intersections.  Where can I find the details?

Answer:  In August, 2009, Caltrans issued a Policy Directive about new requirements for bicycle detection at signalized intersections and new guidelines for traffic signal timing to accommodate bicycle travel speeds.  You can find the full document at http://www.dot.ca.gov/hq/traffops/signtech/signdel/policy/09-06.pdf.  The document describ...


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Traffic signal basics

Posted by Steve Fitzsimons on Friday, July 10, 2009, In : For the General Public 

Question:  How does a traffic signal work and why don’t I get a green when I’m on a motorcycle?

 

Answer:  The short answer is traffic signals work just like a person would who is directing traffic.  First it “sees” a vehicle that needs a green, then it provides the green.  Most traffic signals “see” with detector loops that are buried in the pavement.  These loops detect masses of conductive metal.  They detect large masses, like cars or trucks, very well.  If properly installed...
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About Us


Steve Fitzsimons If you would like to ask a question about driving rules, traffic signals or street lights, send your questions to: SFitzsimons@W-Trans.com or call 650-314-8313. Steve Fitzsimons is a professional Civil Engineer and Traffic Engineer in California. He is a principal at W-Trans. Find out more about W-Trans at www.w-trans.com **** If you need a traffic signal design or review, W-Trans is available for hire. If you are an electrical contractor, W-Trans is available for hire to prepare timing plans or traffic control plans.

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