How pending changes will help at Fairgrounds and Central Valley

The in basket: Ralph Gribbin read a recent article about lane projects coming to the intersection of Central Valley and Fairgrounds roads in Central Kitsap, and questioned some of the assertions made. He wrote to me rather than the existing reporting staff.

“The article states ‘vehicles going straight have to wait for vehicles in front of them to turn left who are waiting for those coming from the other direction to go past,” he said. “NOT SO.  Each direction goes independently from the other three directions, and opposing traffic is at a standstill.

“It also quotes a statement supposedly made by Kitsap Public Works project manager Dick Dadisman ‘There is really nothing wrong the roadway other than turn lanes are needed to get the large volume of traffic through the intersection.’”

“Left turn lanes are not going to eliminate ‘waiting’ at the intersection,” Ralph wrote. “The difference will be the sequence in which each of the eight directions will be waiting. Opposing straight through and right turns will go while while those associated left turners and all cross traffic is waiting.

“The $2 million cost for this change could probably be much better spent in other county road repairs,” Ralph said.

I asked the county to comment, adding that I’d heard discussion of replacing the intersection with a roundabout.

The out basket: Dick Dadisman responded in defense of the expenditure, calling it “a safety and operational improvement project.

“This intersection is ranked 33 of 139 on the county’s high accident intersection list,” he said. “Additionally, with three schools nearby and this intersection located on a county bike route, the safety of non-motorized traffic is also a major concern.

“The proposed project will provide left turn channelization on all legs of the intersection, construct a new eight-phase traffic signal, provide widened travel lanes for improved bicycle safety and construct sidewalks with handicap ramps for pedestrians.

“During the planning stage for this project a roundabout was considered, but it was deemed not appropriate for this intersection.  A roundabout typically requires much more land to construct and sufficient right of way does not exist at this intersection. Additionally, the vertical grades on all four legs of this intersection are not conducive for the construction of a roundabout and roundabouts tend to cause safety issues for pedestrians and bicyclists when compared with a traffic signal, sidewalks and curb ramps.

“Mr. Gribbin’s description of the current traffic signal operation is correct in that ‘split phasing’ occurs on all four legs of the intersection.  This split phasing causes long delays making this intersection operate at an unacceptable level of service.

“Mr. Gribbon is also correct in his operational description of the proposed eight-phase traffic signal. Construction of this project proposes new left-turn channelization on all legs in addition to the new traffic signal.

“A traffic study was prepared where the level of service of the intersection was evaluated.  The study indicates the current intersection level of service (LOS) is F with an average control delay of 95.5 seconds in the PM-peak hour.  For the AM-peak hour the intersection operates at a LOS of D with an average control delay of 47.1 seconds.

 

“Adding the proposed left turn channelization and optimizing the proposed traffic signal cycle length with permissive left-turn phasing on the northbound and southbound approaches and with protected left-turn phasing on the eastbound and westbound approaches, the intersection level of service improves to LOS B.  The control delays will also decrease to 16.6 seconds for the PM-peak hour and 15.8 seconds for the AM-peak hour.

“The decreased control delays are due to left turning vehicles moving out of the travel lanes and into the new left-turn lanes, thereby not choking the intersection,” he said.

Permissive left turn phasing uses flashing yellow lights and protected left turns can be made only with a green arrow light.

 

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