Wednesday, August 31, 2011

The Problem With Fredericton Traffic Lights

      Next month, Fredericton is installing a bicycle-sensing traffic light at the York/Montgomery intersection, which is just one intersection. What about the other several hundred intersections? A few of the older intersections still use underground, metal detecting* activated lights which are completely hopeless to a cyclist since they require a minimum of half a tonne of metal to activate the lights. For instance the Cliffe/Union Street intersection still uses the underground sensors. You can see in the pavement a faint rectangle where the wires are located. The metal of the vehicle triggers the lights to change.

Note the black lines where the wires are located.
     Today's modern traffic lights use a motion sensor activated light. As the name suggest, when a car passes in its vision, it tells the light that there is a car waiting to cross. These lights are more efficient and accurate, but their sensitivity isn't strong enough to pick up cyclists or even motorbikes. Many new signalized and upgraded intersections in Fredericton have this type of light.

The black sensor on top of the light is aimed
 at the centre of the facing lane.
     It would easier for cyclists if bicycle actuated lights were implemented at the major intersections, but I think a simple button would be easier. For instance, this style of light is common on many Vancouver streets. For now, city cyclists will just have to hang behind a car or dismount and use the pedestrian lights.


  1. Actually, most of the lights use induction loops under the pavement, this detects a massive amount of metal above them and changes the light. The cuts in the pavement are actually there because at some point they replaced the loops, or installed them after they repaved the road.

    The optical sensors are actually white and look like cameras. That black sensor you photographed is actually a strobe detector which changes the lights for emergency vehicles.

    The lights downtown are all on times and synchronized to get traffic on/off the bridge quickly.

  2. You maybe be right about the induction loop, but I've always heard of ones that detect weight.

    The black sensors actually are traffic sensors. You can see at major intersections there are two or three to sense turning lanes and traffic going straight. They are cameras:
    As you stated, they are as well strobe sensors. Some intersections like Dundonald/York still use antennas for emergency vehicles.

    Yes, the majority of lights downtown are timed and synchronized for bridge traffic.