Nearly all of Mesa's signals are interconnected and operate as a system to reduce overall delays throughout the City. Mesa's skilled field technicians and staff in the City's state-of-the-art Transportation Management Center (TMC) work together to keep traffic moving.

Vehicle Progression

Vehicles starting out straight (e.g. not making a turn from a side street) at a major intersection at the beginning of a green will experience less stops and delays. The signal timing is adjusted at various times of the day to accommodate the changing traffic patterns. However, there are times when the amount of traffic exceeds the capacity of the roadway. When this happens, backups and delays are inevitable. Carefully planned signal timing helps use the available street capacity to its utmost.

Fire Preemption

Approximately 80 percent of Mesa's traffic signals are equipped with preemption. Fire department vehicles have special coded transmitters that trigger the system. This equipment makes the traffic signal give the green indication to the approaching fire vehicle to help emergency services personnel arrive quickly and safely to where they're needed. You may have noticed the detectors for the system. In Mesa they are typically mounted to the top of the signal head, at the end of the mast arm, over the roadway.

Detecting Cars

The most common method uses a coil of wire embedded in the road surface. An electronic signal running through the wire of this inductive loop is affected by the presence of vehicles. An interface in the traffic signal cabinet tells the traffic signal controller when a vehicle is present based on these inductance changes. The principle is essentially the same as how a metal detector used to find coins on the beach works. If the loop of wire in the street becomes damaged, the traffic signal controller will interpret this as if there were always a car present. This means, for example, that a left turn arrow or side-street indication would be displayed for its maximum time with no vehicles present. Many recently constructed or renovated intersections have video detection which monitor the lane usage through video input. Detection zones are drawn on an image of the roadway. A computer program running inside the detection determines when vehicles enter a zone and pass that information on to the traffic signal controller. There are several advantages to video-based detection such as not being damaged by road work, being re-programmable for situations such as construction where lanes may be moved, and the ability to send images back to the TMC where City staff can see traffic incidents or congestion and make timing adjustments.

Pedestrians

Pedestrian indications consist of a walking person symbol (i.e. "walk" indication) and an upraised hand (i.e. "don't walk" indication).  The walking person symbol means you can begin crossing now.  This indication is typically on for a short amount of time just to get you started.  The flashing hand means if you've started crossing, finish crossing.  The flashing hand also is a warning that if you haven't started crossing yet, don't start because it is too late to safely cross before the signal changes.  If the hand (i.e. "don't walk" indication) is on solid you shouldn't be in the street. When crossing the street, if there is a button present for the direction you are traveling, please press it.  When the button is pressed the controller knows to bring up the pedestrian indications to allow enough time for you to cross.  Without the button press, the traffic signal may only give enough time for vehicles.  Pressing the button doesn't make the signal turn green any faster but it does give more time for pedestrians to cross the street.  If there isn't a button, don't worry, the signal will display the pedestrian indications automatically.

Transportation Management Center

The City of Mesa's Transportation Management Center (TMC) is bringing it all together.  This facility is the nerve center of Mesa's Intelligent Transportation Systems (ITS) efforts.  This facility houses systems which can notify City staff of any unusual incidents.  Based on this information, traffic signals near the scene can be adjusted to better accommodate the change in conditions.  Several key intersections are monitored from the TMC, and City staff is working diligently to expand this technology throughout Mesa. The coordination of these efforts all results in less traffic congestion and delays. This advanced technology also allows TMC staff to work with neighboring cities on monitoring traffic conditions and accidents, making your commute an easier one. The TMC is truly one of the most advanced facilities of its kind in the nation, and the City is pleased to put this state-of-the-art technology to use for the benefit of all who travel in Mesa.

New Technologies

Mesa has switched to LED (light emitting diode) traffic signal indications instead of incandescent lamps.  LEDs use a fraction of the energy when compared to the older technology and they have a life-expectancy of eight to ten years compared to one to two.  Several years ago Mesa started building all new intersections with LED indications and then shortly thereafter a retrofit program began.  The switch to this more efficient technology means that, even with an increase in the number of traffic signals, the electric bill has dropped by over $260,000 per year!