Subscribe to SDOT Blog
T it up
When you are on a bike at a traffic signal, look for the T. When you put your front wheel over it, it tells the signal you are there, the same way that a car driving over the signal detection loops tells the signal they are there. It doesn’t mean it will immediately trigger the signal to change; but makes sure the signal knows you are there waiting your turn too.
Bicyclists have asked “does it matter if your wheel is right on it? Does it matter what your bike is made of?” The bottom line is no. The metal parts on your bike are what is detected. In the future we are moving to a national standard with a bike symbol with a modified “T’ instead of the stand alone T’s. 
(that should make it more obvious for cyclists). A colleague just sent us this video from the City of Redmond. It’s pretty good! It shows the future symbol, as well as explains how to look for the “X” and how to hit the “sweet spot”.
FYI, all jurisdictions are required by a new state law that after July 2009 all new vehicle activiated control signals must detect bicycles and motorcycles. Implementation of the law is subject to funding. We’ve gotten started….so look for the T or bike symbol and ”T it up”.
Posted: August 25th, 2010 under Bikes, Streets for People.
[...] (though probably a very small percentage of bikers in the city, judging by my informal surveying) already know to line up your front wheel with the painted T when they are there. Because the traffic signal [...]
The intersection of 15th Ave NE and NE Pacific St needs these. Motorcycles are not detected by the loop in the left turn lane from west bound NE Pacific St. turning south onto 15th Ave NE. Some hours the left turn signal operates every cycle, but other hours only when triggered, and this can be a problem for motorcycles. Bicycles will just run the light anyhow, so it doesn’t seem to be a problem for them
Thank you for sharing this information and suggestion. It will be forwarded to SDOT traffic operations for review.
Vancouver (the real one…up north here!) has similar loop detectors, though the city planners prefer buttons apparently. They are more reliable, I believe.
One question I asked them, and I’ll ask you: an increasing number of bicycles are made of aluminum (frame and rims) or Carbon Fibre instead of Steel. Will they activate these loop detectors?
From a detection perspective it’s most ideal if bikes will have some component of ferrous metal. However any sort of metal, including aluminum, that’s used as part of the bike frame or wheels will be detected by the loop detectors. A bike with 100% carbon fiber frame and wheels could present a problem for detection by loop detectors. If use of bikes with 100% carbon fiber frame and wheels becomes common on streets we will need to address that issue.
Ooh, can we have one on 77th and Aurora? A lot of cyclists use it to go too and from Green Lake. The light often stays red even when the lights north and south turn.
We’ll ask our signals team to investigate and see if bike detection can be added there. Thanks for highlighting the need for us.
Thanks for looking into this. It would be really nice to have one at that location.
I appreciate that Seattle has had these bike detection markers for quite a while. Sometimes though, I’ve even seen them at intersections without loop detection, which is just kinda weird.
The T bike signals are placed at intersections where we know there is bike activity. SDOT also responds to requests from cyclists to place a bike signal and marking. SDOT uses various types of detection, some of which are not easily visible to a cyclist or motorist, so a T can appear to be “misplaced” when it really isn’t.
I reread the post and caught the bit about moving towards a more standard marking. But why was the non-standard marking chosen in the first place, and why would we need to “move toward” the standard rather than simply switch? Is it just that the Ts are smaller and therefore less expensive?
“In the past, SDOT has used the “T” symbol to indicate the specific location where a cyclists should place their wheel/tire to be detected. However, in keeping consistent with the Manual on Uniform Traffic Control Devices (MUTCD) we are changing to the standard symbol. An image of the symbol can be found at this website.