Bridges and Wildlife


Removing concrete for old Highway 4 lanes


Retaining wall construction


Building undercrossing for Lone Tree Way/A Street


Removing concrete for old Highway 4 lanes


Cutting through old guard rails for Highway 4


Demolishing old bridge over Lone Tree Way/A Street


Constructing new lanes for Highway 4 and wider median for BART

The Lone Tree Way / A Street segment represented the fourth of five phases in the sequence of the Highway 4 Corridor Projects. Widening this segment was not just a matter of laying new pavement: three new bridges were built – an Eastbound Bridge, a Westbound Bridge, and a BART Bridge – with each requiring its own separate stage of construction.

The first stage saw the construction of half of the new Eastbound Bridge as traffic maintained its usual course. During the second stage, both directions of traffic were detoured over this newly-built “Eastbound Half-Bridge” while the new Westbound Bridge and BART Bridge were constructed concurrently. Traffic was then shifted to this new, wider span of pavement. Finally, in the third stage, the remaining half of the Eastbound Bridge was constructed, enabling full utilization of the new Westbound Bridge and the now-complete Eastbound Bridge by their respective directions of traffic.

This staging effort was the primary driver of the increased complexity of the Lone Tree Way / A Street segment, but environmental monitoring continued to present new major complications. One challenge was the discovery of a family of burrowing owls near a retaining wall. Work activities were rescheduled as crews established a 250-foot buffer zone around the nest while bringing in biological monitors. Once the three juvenile owlets were seen flying and hunting, establishing their self-sufficiency, one-way exit doors were installed over the owls’ nesting holes to encourage them “passively” to move elsewhere. This adjustment ensured that construction activities complied with protocols set by the state Department of Fish and Wildlife and the California Burrowing Owl Consortium.

“The improvements to Highway 4 that are brought about with this project and through this partnership are a benefit to every driver that has experienced the traffic congestion on this corridor. We are thrilled to give the new and improved Highway 4 back to the residents of East Contra Costa County and all motorists.”
– Bijan Sartipi, District 4 Director, California Department of Transportation (Caltrans)


timeline iconTimeline: August 2012 to July 2016
segment iconSegment: Lone Tree Way / A Street to Hillcrest Avenue
mileage iconNew lane miles added: 5.91
investment iconCapital investment: $59.8 million
contractor iconContractor: Joint venture between Bay Cities Paving & Grading, Concord, CA and C.C. Myers, Inc., Rancho Cordova, CA

Key Enhancements

  • Widened Highway 4 from four to eight lanes, including a High-Occupancy Vehicle lane in the eastbound and westbound directions
  • Reconstructed the Lone Tree Way / A Street Interchange to provide additional local street capacity, upgraded signalized intersections, and ramp metering capabilities
  • Extended the Pedestrian Undercrossing at Cavallo Road to accommodate the Highway 4 Widening and BART median improvements
  • Constructed the BART median, including a BART bridge over Lone Tree Way / A Street and Cavallo Road
  • Constructed auxiliary lanes in the eastbound and westbound directions of Highway 4