Common Features to Recognize Actuation

Click here for photos of features of actuation

When planning to cross signalized intersections, it is important to know whether the signal is actuated or fixed-time. If it is fixed-time, the timing of the signal may be predictable (however, many signals are programmed to change the timing or even to become actuated at different times of the day). If it is actuated, the only way to ensure that there will be enough time for pedestrians to cross when walking at an average speed is to find and push a pedestrian button for that crosswalk.

The following characteristics can help determine if a signal is actuated. However, none of these characteristics -- absolutely none of these characteristics -- are guaranteed. There are exceptions to every one, some of which are noted. In addition, actuated signals that are damaged will revert to fixed-time until they are repaired, which often takes months, so what may be fixed-time when observed at one time will become actuated after the repair. The only way to know for sure whether a signal is actuated is to call the traffic engineer and even then, it may later be changed without notice.

1. Downtown / Suburb:
Most signals in downtown areas are fixed-time; most signals in the suburbs are actuated (but there are some fixed-time signals in the suburbs, and some actuated signals in downtown areas).

2. Pedestrian button:
If there is a pedestrian button, it is probably actuated. However, pedestrian buttons are occasionally used at fixed-time signals, and many jurisdictions do not provide pedestrian buttons for all or even most of their actuated signals. For example, TWO THIRDS of the actuated signals at state intersections in Maryland have no pedestrian button, and many of these are at streets where pedestrians cross (such as at the intersection between a community college and a large residential area, and at the entrance to a high school). So the absence of a pedestrian button does not mean it's not actuated, it just means that if it is actuated, there is no way for pedestrians to be assured of enough time to cross.

3. Variations in traffic pattern or timing:
If there is a variation in the timing of the signal phases, or variation in the pattern, it's probably actuated. However it there is no variation, it does not mean it is not actuated. For example, there is no variation in the timing or traffic pattern at many intersections during rush hour because the timings are maxed out, whereas the same signal will have extreme variations in timing during times of the day when there is less traffic.

4. Metal box:
If there is a large metal box sitting near one of the corners, it's probably actuated (the signal computer is housed in the box - the control boxes for fixed-time signals are much smaller).

5. Lines in pavement or camera overhead aimed at the lane(s) being actuated:
If there are lines in the pavement where wires have been inserted, or cameras mounted near the traffic signals, it's probably actuated. However when the street is paved or repaired, those lines are covered, so absence of lines doesn't mean it's not actuated.

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