Last week after the City of Houston Town Hall meeting in Kingwood I talked with the representative from Public Works, Joann Clark, about traffic light sensors not tripping the traffic lights when I was on my bike. I gave her three intersections that I frequent and my phone number. She said she would have a traffic engineer call me and we would meet at one of the intersections to see what I was talking about.

Today I got the phone call and agreed to meet the engineer at Woodridge Forest and Northpark Drive with my carbon fiber Stadalli Red Pro 14 to test the traffic light sensors. To reproduce a bie ride experience I put on my cycling apparel and met two traffic engineers. Pictures of the lane where we tested my bike and sensors.

After showing the engineers my bike and all of the carbon fiber they opened the control cabinet to see what the lane sensor was set at. To test the sensor they put an aluminum road sign at the corner of the sensor layout on the street. Next they walked my bike into the sensor area to see if the sensor saw it. It did not. We talked about the amount of metal on my bike which isn’t very much and no magnets at because I use non-magnetic sensors for my Elemnt computer. They adjusted the sensor settings and walked the bike into the area again. Still no pickup by the traffic light sensor. We did this several times with the same result. The engineers were perplexed because they had never tried the sensors with a carbon bike. They tested the sensors with metal bikes and an aluminum bike with a magnet. We moved to another sensor area at the same intersection and still no pickup of my bike. The third sensor area closest to the curb near the east bound Northpark Drive lanes did register the Stradalli this time.

They took the settings from the successful pickup and reset the first sensor. The sensor recognized my bike in the area but not strong enough to trip the sensor to change the light. The sensor could not be adjusted any stronger though to make it trip the light. The engineers were very appreciative to learn about this sensor issue. They are going to advise the City of Houston bike coordinator of what they learned. They are also going to contact the Harris County traffic engineer and TxDOT traffic to see if they have a solution or know about this problem.

What I learned:

• A magnet could help trip the sensor. I am going to add a magnet from a Garmin cadence/speed sensor to the front wheel and try this at the same spot
• The “sweet” spot to trip the sensor is at the corner inside the box.
• Instead of riding on top of the groove where the wires have been buried, ride 6″ inside of the line to the corner.
• In the City of Houston the cameras mounted above the traffic lights are being phased out because they are not reliable.
• Some of the grids in the road use pressure (weight) to trip the sensors but those are being replaced because they are not reliable either.
• If the sensor does not work use the pedestrian button.

I will let them if the magnet works.