Are traffic signals coordinated?
Not all traffic signals are coordinated. Most signal controllers operate on a manually programmed time cycle, dependent on the time of day. Some signals, such as those on St. Clair Street, north of Gregory Drive, Chatham coordinate between signals to develop progression along St. Clair Street. These timing plans are designed to minimize delay and stop time at each signal group. This does not mean that motorists will attain a green light at every intersection, but rather delays along this portion of St. Clair Street are minimized.
How do timing plans work?
Timing plans work by instituting a common cycle length (the amount of time necessary to display all traffic signal indications at an intersection) within a group of coordinated signals. These plans control the points in the cycle length when the signals will be red, amber, or green. By controlling the points when the main street and side street greens occur, coordinated movement through an area can occur.
Will Chatham-Kent install more coordinated signals?
Presently, Engineering and Transportation consider coordination during the planning of all new traffic control signal installations. Total coordination is also dependent upon the rehabilitation or replacement of older traffic control signals located within the Municipality.
Do side street greens come up immediately when a vehicle approaches?
No. As indicated above, signal-timing plans control the points in a cycle when traffic control signals will indicate red, amber, or green. We call this period a "window." Vehicles input a "call" to the signal controller via loop or camera detectors and indicate that a particular movement needs to be serviced. If the calls are input prior to the window appearing in the cycle, the call is serviced at the appropriate time. If the call is input after the starting point of the window, the particular movement must wait for the next window to occur before it is serviced.
How do "walk" signals work?
As indicated above, signal-timing plans control the points in a cycle when traffic control signals will indicate red, amber, or green. We call this period a "window". Pedestrians input a "call" to the signal controller via the pushbuttons and indicate that a particular movement needs to be serviced. If the calls are input prior to the window appearing in the cycle, the call is serviced at the appropriate time. If the call is input after the starting point of the window, the particular movement must wait for the next window to occur before it is serviced.
How are pedestrian crosswalk times determined?
The Ministry of Transportation (MTO) has criteria that establish pedestrian crosswalk times based on the actual crossing distance. The "Walk" time will allow pedestrians to cover half of the crossing distance as this symbol indicates it is safe to start crossing the street. The flashing "Don't Walk" provides enough time for pedestrians who have started to cross the street to complete their crossing before opposing traffic is released. The "Don't Walk" time is the longest component of the pedestrian time as it provides the appropriate clearance time to pedestrians who have started a crossing.
It takes longer for a pedestrian to cross a street than it does for a vehicle. At most intersections, the green signal for side street movements is activated by means of a vehicle detector loop which provides only enough time for a vehicle to clear the intersection. When additional vehicles pass over the detector, additional green time is added to permit them to clear the intersection.
Why doesn't the "walk" indication always come on?
Pedestrian pushbuttons tell the signal controller that a pedestrian needs to cross the street and a longer crossing time is given. The pedestrian pushbutton is the only means of activating the pedestrian signal and obtaining the required amount of crossing time for pedestrians. The push-button will not change the light immediately but will give adequate time for a safe crossing.
Why don't traffic signals flash amber and red late at night when less traffic is on the road?
The Municipality of Chatham-Kent does not use "night flash" operations as traffic studies indicate that collision rates can increase by as much as 300% when this type of operation is used.
What happens to the traffic signals when a fire truck goes through a signalized intersection?
Chatham-Kent Fire Service vehicles are equipped with a device that "pre-empts" normal operation of select traffic signals equipped with appropriate sensors along designated fire routes. During pre-emption, a green indication is given to the signal movement, which the emergency vehicle is using.