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Transportation Management Center 2

What is ITS?  

ITS stands for “Intelligent Transportation System”.  This means that your traffic signal system is interconnected, communicating, and coordinated for the most efficient traffic flow.  It monitors the flow of traffic and allows adjustments to enhance traffic flow.   It also has the ability to adjust for delays such as accidents, construction and special traffic problems, with the aid of traffic cameras installed at major intersections.

ITS PROJECT SUMMARY

The ITS project is funded through a voter approved bond in November 2005 for $3.6M.  Subsequent grants reduced the cost to Issaquah taxpayers by $1.9M.  The initial project phase of the ITS project was subsequently designed and completed by the end of 2006. The City of Issaquah began construction of the remainder of the ITS Project in August 2006 after receiving bids on June 15, 2006 for the 2006 and 2007 construction.  The low bidder was Signal Electric with a bid price of $1,115,105.20.  The scope of work includes the installation of ITS equipment (fiber optic cable, traffic signal communications equipment, CCTV cameras, variable message signs and associated equipments) and supporting infrastructure (conduit, junction boxes, fiber vaults, detector loops and conductors).

The 2005 ITS work program (Phase 1) included completion of the SE 56th Street/SR-900 Corridor and completion of the City’s Transportation Management Center, which is located in the Public Works Engineering Department at City Hall Northwest. (See link at bottom of this page for a map showing the ITS corridors). 

The 2006 Phase 2 work program includes construction of the South Issaquah ITS Corridors on Front Street N, NW Gilman Blvd, NW Holly Street, Rainier Blvd N, E Sunset Way, SW Newport Way, Newport Way NW, Front Street S and the E. Lake Sammamish Parkway Corridor.  This phase also includes two variable message signs: one on East Lake Sammamish Parkway, north of 51st Street for traffic headed southbound, and one at the south end of Front Street South for traffic headed northbound. 

Phase 3 of the ITS project included construction of the Highlands Drive NE and remaining South Issaquah ITS Corridors.  Two other variable message signs were also installed in 2007: on Park Drive east of 10th Ave NE in Issaquah Highlands, and on Issaquah-Fall City Road, east of Highlands Dr. NE.  The project was completed in full in 2008.

ITS OPERATIONS

Public Works Engineering staff has begun collecting traffic data to be used to set up traffic signal timing at each intersection.  After the completion of the construction, signals will be re-programmed and traffic will flow in a coordinated fashion between traffic signals, improving traffic flow and reducing travel time.  The public has seen some incremental improvements on corridors as they are completed and should start seeing the benefits of the fully operational system within about 6 months after the construction is completed for each corridor as the signal timing and coordination is set up, evaluated and adjusted.

Although the traffic signals will be coordinated to synchronize traffic signals on the main street corridors, the overall goal is to reduce travel time and the number of times cars must stop on all corridor streets.  To do this, the system will provide priority to streets that carry more traffic.  This may impact some of the side streets and left-turn lanes of the main street.  To minimize delays at these locations, the City will be monitoring the system for adjustments that may be warranted after the system is in full operation.

The final travel time analysis for the corridors included in the ITS project has been developed.  The travel time analysis compares pre-project travel times to post-project travel times using the signal timing plans that have been implemented under ITS.  Different signal timing plans were developed for morning, mid-day, and afternoon.   Improvements in traffic flow varies throughout the day and by corridor.

Mid-day timing plans have not been implemented at this time, because doing would have a detrimental effect on the system operation.  At some time in the future the City will re-evaluate the need for separate mid-day timing plans as volumes rise and make changes as appropriate.

QUESTIONS

If you have questions about this new system, please contact either Fay Schafi, Senior Traffic Signal Operations/ITS Engineer at 425-837-3422 or Gary Costa, Transportation Manager at 425-837-3443.

LINKS

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