ATC-1000 Operating Manual - Rev 1 - Peek Traffic

Coordination of an Actuated Controller UnitThe "platoon" of vehicles at that intersection will then be released and may arrive at thenext intersection too early, before the green appears. These vehicles will have to stop,which, of course, defeats the purpose of coordination.There are, however, a couple of things to consider relative to this issue. Firstly, despitethe lack of appearance of coordination under such circumstances, the system mayactually be more efficient. Even though the pre-timed system may be well coordinated, itoften does so by arbitrarily holding the main street red as the side streets are providedwith a fixed duration green time, whether needed or not. Conversely, the actuatedmachine returns to the main street as soon as it can. Since some main street vehiclesmay turn off before they reach the next intersection, an early return is certainly beneficialto them. For those that proceed through the next intersection, although they may behampered by arriving too early, they may also have the luck that the next intersectionreturns to main street early as well, and can proceed unimpeded. This type of operationprovides maximum efficiency although it can occasionally appears sporadic andunpredictable.This leads to the second point: proper coordination using actuated controllers requiresthat the responsible agency provides the proper cycle and split settings for the level anddistribution of traffic at any given time of day. If the cycle length and split times areappropriate for the conditions at all times of the day, non-beneficial early returns to themain street can be minimized.ATC-1000 Advanced Traffic Controller 189