SB Valley Coordinated Traffic Signal System Plan

Tier 1 & Tier 2
The Tier 1 program began engineering, design and equipment procurement in 2002 using Congestion Mitigation/Air Quality (CMAQ) funds. Construction and timing implementation was completed in September 2008. Tier 1 improved and coordinated 299 signals on east-west arterials along the I-10 and SR-60 corridors and north-south arterial segments that will improve traffic flow between the east-west arterials and linkages to the freeway. 

• See maps of Tier 1 & Tier 2
• Tiers 1 &2 Final Report

Tier 2 of the program improved and coordinated 294 signals along major arterial streets in the San Bernardino Valley.

A progress report for both Tier 1 and Tier 2 will be completed in early 2009 to evaluate the traffic flow improvement and emission reduction.

Tier 3 & Tier 4
The remaining two tiers (Tier 3 & 4) are estimated at $6.5 million. Tier 3 program will improve and coordinated 145 signals on north-south major street between Route 210, Interstate 10 and Route 60. Tier 4 of the program will improve and coordinate 325 signals along other major streets in the San Bernardino Valley. Funding for Tier 3 & 4 will be a combination of CMAQ funds and Traffic Light Synchronization Program (TLSP) funds under the Proposition 1B Bond. A Request for Proposal for design and develop a signal-timing plan will be issued in November 2008 upon SANBAG Board approval. Tier 3 & 4 is expected to be completed by Dec ember 2011.

• See maps of Tier 3 & Tier 4

• Q: What is Traffic Signal Coordination?
  A: Traffic signal synchronization is a method of timing groups of traffic signals along an arterial to provide smooth movement of traffic with minimal stops. The quality of the resulting progression is a function of the spacing of the signals, the prevailing speeds, the amount of traffic coming in and out of driveways between traffic signals, the uniformity of intersection sizes, and the cycle length.
• Q: Why does it take so long for the signal to turn green?
  A: To allow the coordination of the arterial, the side street must wait until the main traffic movement on the arterial has gone through the intersection. It is possible that the arterial traffic can't be seen immediately, but will soon be passing through the intersection.
  
  The goal of signal coordination is to get the greatest number of vehicles through the system with the fewest stops in a comfortable manner. The reduction of large numbers of vehicles sitting idle at an intersection leads to a reduction in vehicle emissions. It would be ideal if every vehicle entering the system could proceed through the system without stopping. This is not possible even in a well-spaced, well-designed system. Therefore, in traffic synchronization, "the majority rules" and the busiest traffic movements are given priority. Depending on a route, the master cycle length of an arterial could vary from 60 to 120 seconds. This means that if you were exiting a side street, and you just missed the light, it is possible to wait between 60 and 120 seconds, or whatever is the cycle length, before receiving another green light. Generally, the busier and the larger the intersection, the longer the required cycle length.
• Q: Why is this particular street not included in the traffic signal coordination plan?
  A: Not all streets warrant coordination. Typically, a street is selected for coordination if it carries a certain amount of traffic along the arterial during peak hours. In most cases, coordination is active from 7:00 a.m. to 7:00 p.m. during weekdays. The individual signals operate on a “first-come-first-served” or traffic activated basis outside of these hours, or all the time if a street is not selected to be synchronized.
• Q: Will I be able to tell the difference when traveling on an arterial with traffic signal coordinated?
  A: During peak hours motorists who drive at an appropriate speed should notice fewer red lights during their commute.