Highway 101 / Greenbrae Interchange project

MCL endorses the TAM Working Group’s final recommendations for the Hwy 101 Greenbrae/Twin Cities Corridor Project, subject to environmental review and resolution of environmental issues related to completion of the north-south greenway.

Position approved by the MCL Board of Directors on September 17, 2013


Greenbrae InterchangeAfter several years of planning, CalTrans and the Transportation Authority of Marin (TAM) have developed designs for a major project (TAM Build Plan) along Highway 101 in the corridor from Sir Francis Drake Blvd. in Greenbrae to Tamalpais Drive in Corte Madera. The project, projected to cost in excess of $150 million, focused on reconfiguring freeway access in this corridor by eliminating the existing Lucky Drive interchanges and replacing them with interchanges at Wornum Drive. In addition, traffic headed south from Sir Francis Drake Blvd. would be substantially rerouted.

The project has engendered a substantial amount of criticism from the community. On August 26, 2013, the TAM Greenbrae Corridor Working Group, which was formed of community members to offer an alternative to the the massive project,  finalized its recommendations for submittal to the full Transportation Authority of Marin (TAM) Board, which is expected to vote on them at the TAM Board meeting on September 26. These recommendations are the result of five months of study by the TAM Working Group, whose members devoted many long hours to analyzing various concepts for making improvements in the Greenbrae/Twin Cities Highway 101 Corridor. The issues in this location are complex, due to significant factors outside the project area, which the Working Group recognized in their multi-pronged approach to considering several different and seemingly disparate strategies for addressing them. It should be noted that the TAM Working Group rejected virtually all aspects of the TAM Build Plan that have engendered so much public opposition and were shown to have very limited benefits.

The TAM Build Plan
CalTrans, which is the “lead agency” for the federally funded project under both the California Environmental Quality Act (CEQA) and the National Environmental Policy Act (NEPA), has aggressively taken the position that this massive project will not have any substantial environmental impacts. Accordingly, CalTrans asserts that it is not required to do either an Environmental Impact Report (EIR) under CEQA or a Environmental Impact Statement (EIS) under NEPA. Instead, based on a finding that the project will not have any substantial environmental impact, CalTrans plans to issue a “Mitigated Negative Declaration.” TAM has previously claimed that the studies and assessments that it has done over the past several years are the equivalent of an EIR/EIS but it may be changing that assertion.

Materials about the project and its complex approach to routing traffic in this congested area can be reviewed at the TAM website, including detailed maps and links to “YouTube” animations simulating the new traffic flow.

The principal changes include:

1) Southbound 101—The Lucky Drive off ramp will be eliminated and would be replaced with a new interchange at Wornum Dr. (see screenshot from video simulation, below.) The existing interchanges at Sir Francis Drake, Madera Blvd. and Tamalpais Dr. would be retained. Travelers going from SB 101 to the businesses on the west side of Lucky Drive, to Redwood High School, or to downtown Larkspur would exit at Wornum and then double back on Tamal Vista to Lucky Drive. Because of the rerouting of traffic from Sir Francis Drake, the new Wornum Drive off ramp would include a massive elevated “flyover” structure. A new “auxiliary” lane would be added to the freeway from Wornum to Tamalpais to ease congestion. CalTrans has abandoned its earlier proposal to eliminate the Madera Blvd. exit.

2) Northbound 101—The Lucky Drive interchange would also be eliminated in the Northbound direction. Northbound traffic would be able to exit the freeway at the new Wornum Drive exit, which will provide access to businesses and residential areas on both sides of the freeway. A new off ramp, just before Wornum, would take traffic heading to Sir Francis Drake and the Richmond Bridge. An auxiliary lane will be added from Tamalpais Drive to the new Sir Francis Drake off ramp. Traffic from the Village and the Cost Plus shopping centers headed to northbound 101 would enter the freeway at Wornum, rather than at the current location at Industrial Blvd.  A ramp at Industrial Blvd. would continue to take traffic headed to Sir Francis Drake but no longer provide freeway access.

3) Sir Francis Drake—Traffic from both east and west Sir Francis Drake headed to 101 South and/or across Corte Madera Creek would enter an on-ramp at the current location, widened to two lanes and extended so that traffic enters the freeway south of Wornum. The extended freeway approach will have an exit at Fifer and at Wornum before reaching Highway 101. The route for traffic headed to101 North will be substantially unchanged.

4) East/West access across Highway 101—Each of the three roads that currently cross over or under the freeway in this corridor would remain: (a) Sir Francis Drake (north of Corte Madera Creek), (b) Wornum Drive, and (c) Tamalpais Drive (both South of Corte Madera Creek). The new Wornum Drive interchanges will make this crossing significantly more important, however.

5) Bicycle/Pedestrian Routes—The project envisions upgrades to the bicycle and pedestrian paths across the freeway, across Corte Madera Creek and on adjacent surface roads. Both of the existing paths for crossing Corte Madera Creek would be widened to current Class I standards, and new bicycle paths added to Tamal Vista Drive, requiring the elimination of the existing central turn lane. The existing pedestrian bridge across the freeway, (pictured above), located near the current Lucky Drive freeway exit, would be eliminated. Pedestrians and cyclists who relied on this bridge will have to cross underneath the freeway at Wornum. The existing multiuse path north of the Corte Madera Creek would remain.

It appears that this will be the most complex freeway project ever proposed in Marin. It is hard to envision that a project of this magnitude would not have any substantial environmental impacts. For example, at Wornum Drive, the freeway and the new ramps/auxiliary lanes would be a total of eighteen lanes wide. The project is located in an area of extensive tidal wetlands and typically low elevations frequently subject to flooding from the combination of tides and upland runoff, but it appears that the plans do nothing to accommodate the impacts of sea level rise.

2013 Documents and Correspondence

February 13, 2013 - MCL comments on DED to TAM

February 13, 2013 - MCL comments on DED to Caltrans

The Draft Environmental Document (DED)

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