|In the Town of Bridgewater there are 10 intersections that currently have traffic signals. There are two primary types of traffic signal control used throughout Bridgewater – Pre-timed Signal (fixed) operation and Actuated Signal operation.
Pre-timed Signals (fixed): At pre-timed traffic signals each signal phase or traffic movement is serviced in a programmed sequence that is repeated throughout the day. Main street traffic receives a fixed amount of green time followed by the amber and red clearance intervals. The same interval timing is then repeated for the minor or side street. The amount of time it takes to service all conflicting traffic movements is referred to as the cycle length. Pre-timed signals can provide fairly efficient operation during peak traffic periods, assuming signal timing settings reflect current conditions. However, during off-peak times, particularly at night, traffic on the major roadways are often stopping for no reason because of little or no traffic or pedestrians on the cross streets. With pre-timed signals the only method to avoid unnecessary delays is to change the timings during off peak hours and have shorter cycles or make the signals actuated. In Bridgewater there are currently three intersections that are pre-timed (fixed) and are proposed to be upgraded in the future.
Actuated Signals: Actuated signal control differs from pre-timed in that it requires “actuation” by a vehicle or pedestrian in order for certain phases or traffic movements to be serviced. Actuation is achieved by vehicle detection devices and pedestrian push buttons. The most common method of detecting vehicles is to install inductive loop wires in the pavement at or near the painted stop bar. Actuated signals consist of two types: semi-actuated and fully-actuated.
Semi-actuated – vehicle loop detectors are installed on the minor street approaches and push buttons are provided for pedestrians wanting to cross the major roadway. The traffic signals remain green on the major roadway until either a cross street vehicle is detected or a pedestrian pushes the button. When this occurs a “call” is sent to the traffic signal controller and at the appropriate time in the cycle main street green will terminate and time its clearance intervals before the minor street is serviced. If the side street is servicing vehicle demand only, a minimum green of 5-7 seconds is provided which can extend up to a preset maximum provided additional vehicles are being detected. After the last vehicle passes over the detector loop or the preset maximum green time has been reached, the signals will return to a green state on main street. If the side street is servicing a pedestrian demand, the “walk” and “flashing don’t walk” signal indications will be displayed, again at the appropriate time in the cycle. At pedestrian actuated signals, the “walk” indication is displayed for 5-7 seconds. This allows the pedestrian to enter the crosswalk and begin crossing. At the end of the “walk” signal the “flashing don’t walk” indication is displayed which provides the pedestrian already in the crosswalk sufficient time to safely complete their crossing and clear the intersection before conflicting traffic receives a green signal. Pedestrians who are already in the crosswalk at the start of this interval continue to have the right of way over turning vehicles. Pedestrians who have not begun to cross when this interval begins should wait until the next cycle. In Bridgewater we currently have 2 intersections that are semi-actuated.
Fully-actuated – vehicle detector loops and pedestrian push buttons are installed on all approaches. All signal phases including left turn arrows have preset minimum and maximum greens and will be serviced on demand only. Pedestrians must activate the push buttons in order to receive the “walk” and “flashing don’t walk” indications. A single press of the button locks the “call” in the controller’s memory that a pedestrian has requested service. Fully-actuated signals are most efficient at isolated locations where coordination with adjacent signals is not a concern and where the intersecting roadways have similar traffic volumes.
Actuated signal control provides greater efficiency compared to pre-timed signals by servicing cross street traffic and pedestrians only when required. The primary disadvantage with pre-timed signals is avoided as main street traffic is not interrupted unnecessarily. This is particularly beneficial during off peak conditions. The result is fewer stops and delays to traffic on the major arteries, while still providing for safe pedestrian crossings as and when required, which ultimately leads to a decrease in fuel consumption and pollution. In Bridgewater we currently have 5 intersections that are fully-actuated.
Currently all the street lights within the street right of way in the Town of Bridgewater are owned and maintained by Nova Scotia Power and are rented by the Town. If you notice a street light burnt out in your neighborhood please notify Nova Scotia Power directly by the following link: http://www.nspower.ca/en/home/residential/services/streetlightrepairs.aspx