Traffic Signals

"To assist traffic engineers in reducing unnecessary vehicle stops and delays through more efficient traffic signal timing."  Traffic signal synchronization involves a coordinated set of timing plans for groups of signals on an arterial to create smoother traffic flow, ultimately increasing car and bus mobility with the fewest stops at intersections and decreasing traffic congestion.

Strategies and Greenhouse Gas Emissions
Prioritize the monitoring of traffic signal synchronization in the City.  Would include an estimated emissions reduction of 435 tons of CO2.

Cost to the City
It depends upon the range of the project.  Based on estimates in Portland and Seattle, traffic signal synchronization of thirty-five to thirty-seven lights would cost approximately $70,000 to $185,000.  However, in Syracuse, NY, synchronizing 145 intersections brought the total project cost up to $8.3 million.

Barriers

  • More staff needed for signal synchronization
  • Locating funding sources for additional staff time and new technology
  • Planning and design of new surveillance technology
  • Unique demands of intersections, including geometry and spacing
  • Need for continuous readjustment in the face of new development

Benefits

  • Estimated fuel savings of 28,505,088 gallons, and a monetary benefit to drivers of up to $485 million.  Fuel consumption may decrease by 2 to 9 percent.
  • Improve traffic flow along any given corridor in Tacoma, reducing delays and stops, allowing Tacoma motorists to enjoy a quicker commute
  • May reduce response time for emergency vehicles
  • Minimizes diversion of traffic to residential areas, thus improving local safety
  • Improves safety and economy as a whole; 43,000 Americans die on national highways each year, and "hundreds of billions of dollars lost in traffic congestion weigh down the economy," and intelligent transportation systems (ITS) will make strides to help this factors.  ITS can decrease crash frequency by 31 percent.

Partners
This will be a partnership between the City and traffic management personnel, though additional help from county officials might be needed, as well as assistance from emergency aid vehicles.

Tasks

  • Efficient training of traffic staff in the use of computer technology
  • Does the technology currently exist to manage traffic synchronization? Replace outdated technology if necessary.
  • Determine whether it's needed to have a "smart" system that self-corrects problems with traffic lights, or continue to have engineers manually reset lights
  • Have emergency and road-clearance vehicles ready with appropriate personnel
  • Enforce existing laws regarding road clearing after collisions
  • Provide system for travel time forcast through signs, radio stations, phone, and the internet

Success Stories
Syracuse, New York (Peer Cities)
Syracuse enacted a plan that included a computerized traffic light system, and synchronized 145 intersections.  The total cost of the project was $8.3 million - a detailed breakdown of costs is listed on the Web site link in "related information."  Fuel consumption was estimated to have been reduced by 9 to 13 percent, with reduced delay by up to 14 to 19 percent, total stops decreased by 11 to 16 percent, and the average speed was increased by 7 to 17 percent.

Austin, Texas
While a city as large as Austin still has many difficulties with traffic congestion, it has nonetheless made huge strides in improving some sections of the city's street grid.

Fredericksburg, Virginia
Even minor changes in three traffic lights can improve traffic congestion, cutting travel time by nearly half.

St. Augustine, Florida
A reduction of 36 percent in delay, 49 percent in stops, and 10 percent in travel time, resulting in savings of 26,000 gallons of fuel and cost savings of approximately $1.1 million.

Portland, Oregon
A thirty-five traffic signal system in Portland, Oregon netted an annual fuel consumption reduction of over 175,000 gallons for a project cost of $70,000.

King County, Washington
King County created a plan to synchronize traffic signals within the county, a $415,000 effort to ease traffic congestion.  In Seattle alone, the city planned to use $185,000 to synchronize thirty-seven traffic signals.  Many areas within the county noticed increased speeds through corridors normally bogged down with cars, as well as a decrease in total travel time of about twenty percent.