Traffic Signals

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Questions or complaints concerning the operation of individual traffic signals should be sent through our request/complaints procedure.

Reports of malfunctions should be reported immediately to the following phone numbers:

Weekdays

7 a.m. to 5 p.m. Public Works Department - Engineering Division - 434-2225

5 p.m. to 7 a.m. Police Department - 820-8888

Weekends and Holidays

Police Department - 820-8888

General Information

The City currently maintains traffic signals at 147 intersections. Some traffic signals are owned jointly with other agencies such as the Town of Normal, McLean County, and the Illinois Department of Transportation (IDOT). The City is reimbursed quarterly from the other agencies for their share of the actual maintenance and energy costs according to intergovernmental agreements.

Some signalized intersections are part of a coordinated signal network. When intersection spacing is less than 1 mile, signal coordination is beneficial to moving traffic safely and efficiently through the signalized intersections along main arterial corridors. There are 3 main coordinated signalized networks in Bloomington. They are the Veterans/Empire, CBD - Central Business District, and West Market systems. Signalized intersections with spacing of one mile or more typically run independently in a "fully actuated" mode. This means that the signal cycles based only on traffic that is present in the zone of detection.

Vehicle detection at signalized intersections can be done using many technologies. One of the oldest and most common is the induction loop. A loop of wire is installed in the road pavement that connects back to the traffic signal cabinet. When a vehicle crosses the loop, the inductance of the loop of wire changes which indicates the presence of a vehicle. Loops typically need to be replaced when a road is resurfaced. Newer technology includes video or microwave. These technologies allow the zone of detection to be adjusted more easily and are more sensitive in detecting motorcycles and bicycles.

The City and State use software called "Synchro" by Trafficware to assist in developing signal timing programs on a personal computer. A traffic model is custom built in Synchro for each signalized network and includes items such as traffic volume for each direction and movement, number of lanes, storage lengths, intersection spacing and speed limits. Since traffic volumes vary by time of day and day of week, several models are developed. In the case of the Veterans/Empire network, there is a separate program for AM, mid-day, PM and night as well as one for Saturdays. Traffic counts collected on 15 minute intervals are used to determine what time of day traffic patterns change. This information is used to determine the start and stop times for each of the programs. All the signalized intersections in the same network share the same cycle length which allows vehicles to move through the network in a predictable and repeatable pattern. The intersections in these coordinated networks typically run in a "semi-actuated" mode. Turn lanes and side streets are only serviced when there are vehicles present. Any time not needed for the side street is given back to the main arterial road. This means the beginning of the green for roads such a Veterans Parkway is variable depending on side street traffic. The actual coordination reference point occurs during the green period for the main arterial road.

Some traffic signals in the CBD network operate only in a "pre-timed" mode. This means that the signal is not actuated in any way by the actual traffic present, but it just operates the same way each cycle. Cycle lengths vary by program and signalized network. The longest cycle lengths in a coordinated program are 140 seconds long during the AM, PM and Saturday programs for the Veterans/Empire network. Connected side street arterials such as Hershey, College, Vernon, Washington, Oakland, and Towanda are part of the Veterans/Empire network. They run the same 140 second program during the AM and PM programs. During off peak periods many of the signals on these other connected arterials are allowed to run free or in "fully actuated" mode.

The timing programs for each intersection are stored in a database on a network server. Many of the signalized intersections are inter-connected on a dedicated fiber optic or copper cable. The programs can be loaded remotely from the server into the traffic signal controller at each intersection. Traffic signal controllers that are not connected by a network cable have to be programmed in the shop or in the field. The connected intersections can be remotely monitored from the office. Some intersections along Veterans Parkway and Empire Street have PTZ - Pan, Tilt, Zoom cameras which can be panned and zoomed to study traffic patterns and identify issues remotely. Recently, IDOT added PTZ cameras to the Interstate System around Bloomington-Normal. Staff at the METCOM 911 center have access to the PTZ cameras to help with incident management and emergency operations.

IDOT also has variable message boards on the interstate system just before traffic enters the Bloomington-Normal area. The messages displayed can be changed remotely to advise motorists of adverse road conditions, traffic backups or other important information. The message boards and cameras are part of a larger state wide ITS - Intelligent Transportation System. Some of this information is available to the public at www.gettingaroundillinois.com or www.gettingaroundpeoria.com.

Because the safe movement of traffic is critical on the larger transportation networks like Veterans Parkway, the City and State partnered to provide battery backup (UPS) for some of the critical traffic signals. A UPS project for all the intersections on Veterans Parkway was completed in 2012. The battery backup system is designed to provide at least 4 hours of traffic signal operation in the event of a power outage. Intersections without a battery backup go dark in a power failure. Illinois law requires motorists to treat a dark signalized intersection as an all-way stop. The traffic signal will resume operation once the power comes back on.

All new traffic signals include battery backup systems with LED signal heads for energy efficiency. One drawback of the LED signal indications is the lack of heat they generate compared to incandescent bulbs. In winter strong winds can blow snow and ice onto the signal face making it difficult for drivers to see what color is lit. This is especially bad in early morning hours as the sun begins to rise causing additional glare and contrast issues. Drivers should be extra careful when approaching a traffic signal if they can't see any color of light.

The City works in cooperation with IDOT and the Town of Normal to provide optimum signal timing across jurisdictions. Signal malfunctions should be reported to the City. Critical issues such as a signal that has been hit, damaged or knocked down, should be reported immediately to the police by calling 911. Other non-critical issues such as a dark (i.e. burned out) indication should be reported to the Public Works Department during regular business hours at 434-2225.