Officials with the Valley Transportation Authority (VTA) and the City of San Jose Department of Transportation presented proposed changes to the I-880/I-280/Stevens Creek/Winchester interchanges at a public meeting on July 22.
Margaret Simmons-Cross, Highway Program Manager at the VTA, presented the proposed changes. There are three main focus areas of the changes: The I-880/Stevens Creek Boulevard interchange, the I-280/I-880 interchange, and the I-280/Winchester Boulevard interchange.
I-880 / Stevens Creek Boulevard
The current configuration of the I-880/Stevens Creek Boulevard interchange is known as a Cloverleaf design. This was a popular design when the interchange was constructed in the 1950s. The chief advantage of cloverleaf designs was that they were free-flowing and didn’t require the use of such devices as traffic signals. A problem with this design is the merging of exiting and entering traffic in the same lane, known as weaving.
The proposed changes to the interchange would turn it into a Diamond design. This would require additional traffic lights on Stevens Creek. A strict Diamond design has no loops, but the I-880/Stevens Creek interchange will retain the loop from Eastbound Stevens Creek to Northbound I-880, making this interchange a hybrid of a Diamond and a Parclo (partial cloverleaf interchange) design.
The Southbound I-880 to Westbound Stevens Creek exit will also feature a dedicated lane for North Monroe Street that bypasses the traffic signal, which will handle the traffic destined for Westfield Valley Fair and other parts northward. VTA found that about 30% of all traffic using this exit was destined for North Monroe Street.
I-280 / I-880
This new connector will separate the regional traffic that wants to go from I-280 Northbound to I-880 Northbound from the local traffic that is destined for Stevens Creek. In the present design, traffic utilizes the same ramp system to both Stevens Creek and I-880, requiring merging and jockeying for position. Traffic destined for I-880 Northbound will use the new connector, and traffic destined for Stevens Creek will use the existing ramps.
I-280 / Winchester
Winchester Boulevard is presently only half-connected to I-280. Traffic can only enter Winchester Boulevard from I-280 in the southbound direction, and traffic from Winchester Boulevard can only enter I-280 in the northbound direction. Designers have produced two different designs for a I-280 northbound exit onto Winchester Boulevard – a five-legged intersection and a hook ramp design.
Both designs connect with Tisch Way just east of Winchester Boulevard. One design would turn Tisch Way into a one way street traveling westbound. The other would be a hook design, adding an additional traffic signal where the ramp meets Tisch Way. Officials have not chosen a design nor is one design favored over the other.
Q & A
After the presentation, Simmons-Cross was joined by Ray L. Salvano, a Senior Engineer with the City of San Jose Department of Transportation.
Residents raised two main concerns with the changes.
Residents overwhelmingly supported the I-280 / Winchester design that kept Tisch Way a two-way street. Area residents use Tisch Way and South Monroe Street as an express route to go from South Winchester Boulevard to I-880. This route only has a couple stop signs. The alternative route – traveling north on Winchester and then east on Stevens Creek – has drivers encountering 5 additional traffic lights.
The second concern was the new ramp to Winchester Boulevard would only handle traffic from I-280 east of I-880. This means that traffic from southbound I-880 could not use the same ramp to exit onto Winchester Boulevard. This traffic would need to exit at Stevens Creek Boulevard and navigate along Stevens Creek or along South Monroe Street and Tisch Way.
The project is divided into two tiers. The first tier is the I-880/Stevens Creek and I-280/I-880 improvements, and construction could start in the next 18 to 24 months. The Winchester exit is a tier two project, and construction would be expected to be 10 years away. Total construction cost is expected to be $130 million – $150 million.
A draft environmental impact report will be released in January 2010. Citizens will then be able to write down their comments and there will be additional public meetings before the environmental report is finalized. People with questions can contact the VTA’s Community Outreach Department at (408) 321-7575, visit the web site at www.vta.org, or email at firstname.lastname@example.org.