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US 101 Auxiliary Lanes


The project constructed auxiliary lanes in each direction of a 3.2-mile segment of U.S. 101 between State Route 85 in Mountain View and Embarcadero Road in Palo Alto.

View a map of the project.


The purpose of this project was to relieve existing and future traffic congestion along U.S. 101 between State Route 85 in Mountain View and Embarcadero Road in Palo Alto, and to improve safety along the U.S. 101 corridor in Santa Clara County by eliminating bottlenecks while providing additional capacity for vehicles to merge.

Project Features

The project improvements included:

  • Constructed auxiliary lanes between on-ramps and off-ramps
  • Extended existing high-occupancy-vehicle (HOV) Lanes
  • Widened and modified on-ramps and off-ramps at each interchange to improve efficiency of the auxiliary lanes  
  • Improved traffic operations on the freeway by providing more room for traffic entering and exiting the freeway at each interchange
  • Allowed traffic traveling from one interchange to the next interchange to use the freeway without impacting the main through lanes


Caltrans operates and maintains the highway improvements.

Capital Cost / Project Funding

$72 million: $56 million in Corridor Mobility Improvement Account (CMIA) Funds, $16 million in VTA Local Program Reserve Funds.

Project Schedule

2007-2009 Environmental Studies
2009-2011 Design and Engineering
Spring 2012 Began Construction 
Summer 2014

Completed Construction                                                          

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