MHD bicycle detection document

The Massachusetts Highway Department published the document Bicycle Detection at Signalized Intersections in 1998. This includes the recommendations for quadrupole loops in the 1986 San Diego study, which is cited as a reference. The Massachusetts document reflects progress, in recognizing the importance of bicycle detection, but includes some recommendations which reflect an inadequate understanding of bicycle characteristics and operation, notably:

Bicycle markings should be placed to the right side of general purpose through lanes to conform to recommended bike-riding practice (allowing the faster accelerating cars to pass within the lane).

Because a bicyclist needs to actuate the signal when first to arrive at a red light, waiting toward the left side of a through lane which also allows right turns can offer the courtesy to motorists to turn right legally on red, and avoids the risk of a “right hook” collision. The bicyclist can merge back to the right side of the lane (assuming that it is wide enough to share) once the light has changed.

The report later reiterates the recommendation to place the detector at the right side of a lane, along with others, stating that a detector should be placed

1. In a dedicated bicycle lane.
2. On the right side of the right travel lane.
3. On the left side of a left turn lane (if the lane is a shared use lane for left and through movements).
4. On the right side of a left turn lane (if lane is an exclusive left turn lane).
5. Just to the right of the centerline when turning left on an ordinary, two-lane street.

Therefore, bicycle detection should be placed at locations described above. It is not practical to force bicyclists to ride in traffic situations where they are not comfortable or are in conflict with recommended bicycle safety practices. We suggest that each intersection be evaluated individually for bicycle detection.

These locations are incorrect or insufficient. A bicyclist who is waiting at a red light is otherwise not impeding the travel of anyone else except possibly a driver who would like to turn right. The bicyclist should never wait at the left side, in a lane which allows left turns, encouraging a motorist to pass on the right and force the bicyclist into oncoming traffic after turning.

The document lists several types of detectors besides loop detectors: video, microwave/radar, sonic, magnetic and magnetometers, the only one to which it gives a strong recommendation; but in mentioning magnetic detection and magnetometers at all, it is mistaken, because aluminum bicycle and motorcycle rims are nonmagnetic and will not be detected.