Regional Traffic Operations Center (RTOC)

Regional Traffic Operations Center (RTOC)

Regional Traffic Operations Center

The Arizona Daily Star recently ran a series of transportation related articles. An interesting statistic from one article was that since 1985 the population of Tucson had increased approximately 24 percent. During that same period, travel increased approximately 77 percent while the street network only increased by 4.3 percent.

Obviously we are facing times of increased traffic congestion and air quality concerns. One way public officials are addressing increasing traffic demands is by upgrading and enhancing the central signal system.

The Regional Traffic Operations Center monitors and controls nearly every traffic signal in the Pima County area. Working partners in the system include the State of Arizona, Pima County, City of Tucson, City of South Tucson, Town of Marana, Oro Valley, and the Pima Association of Governments.

The City of Tucson manages the RTOC. Monitoring is or will soon be available to each partner jurisdiction. The system was established in the mid 1970's and is one of the few multi-jurisdictional traffic signal systems in the United States.

The central system has been recently upgraded. It is a PC based windows system. The system communicates once per second to every intersection providing status updates and alarms to central. The system offers several advantages over older legacy systems:

  • Improved reliability
  • Ease of expansion
  • Easily upgraded

In addition to the arterial traffic signal system, the State of Arizona has installed a Freeway Management System (FMS) that includes cameras, variable message boards, and a fiber optic communication backbone along the Tucson freeway system. These devices are monitored by the RTOC as well at City 911, the Department of Public Safety (DPS), and the Arizona Department of Transportation (ADOT).

Together, all of these devices result in a very sophisticated traffic system efficiently controlling the existing roadway network. However, the most advanced electronic devices, optimized signal timing, etc. cannot compensate for the disparity in population growth vs. roadway expansion. Commuters need to plan their trips accordingly.

Tools of The Trade

Software is used to analyze the performance of the current system and future improvements. Following are snapshots of software applications used in the RTOC.

Progression Analysis Tool

Progression Analysis Tool Screenshot

Analysis of progression for Broadway Blvd. The Red-Green bands represent(top to bottom): Swan Rd, Rosemont Blvd, Williams Blvd and Craycroft Rd. The image shows the loss of progression with ¼ mile signals.

Progression Analysis Tool Screenshot

The above image shows Kolb Rd, Prudence Rd and Pantano Rd. Here you can see the good progression between properly spaced intersections.

System Monitoring Software

System Monitoring Software Screenshot

This map depicts all regional signals and their current status. This map is updated every second. The dots represent: Green = OK, White = No communications and Flashing Red = Intersection on Flash.

System Monitoring Software Screenshot

We can also look at any particular intersection to monitor the local operation. We can see who has a green light, if pedestrians are trying to cross and if cars are traveling or waiting in any particular lane.


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