Yerba Buena Island Forest Road detour to I-80 eastbound on-ramp takes effect August 2nd

Treasure Island Road will close south of the Macalla Road intersection on August 2nd. All vehicles traveling to the East Bay will detour through YBI to reach Hilllcrest Road and the I-80 eastbound on-ramp.
July 02, 2023
A traffic circulation map of Yerba Buena Island displaying vehicle routes to and from the YBI Bay Bridge ramps

Forest Road detour road to I-80 eastbound YBI on-ramp opens August 2nd

Beginning August 2, 2023 and continuing through 2026, Treasure Island Road will close to all traffic south of the intersection at Macalla Road on Yerba Buena Island in order for the start of substantial construction on the Westside Bridges Retrofit Project.  All traffic to westbound I-80 (toward San Francisco) will continue using Macalla Road to access the westbound I-80 on-ramp as you have been since June 26, 2023.

  • All vehicles and trucks (WB-50 or SHORTER) wishing to travel eastbound on I-80 (toward Oakland and points beyond) will use Macalla Road, then turn right onto Yerba Buena Road, then left onto Forest Road Detour, and then left onto Hillcrest Road where you will then merge onto the eastbound on-ramp to I-80/Bay Bridge.
  • All trucks LONGER than WB-50 must use Macalla Road to the westbound I-80 on-ramp (toward San Francisco) and then use the 5th Street Off/ On-Ramps in San Francisco to turn around to travel eastbound (toward Oakland and points beyond).

Detour road allows for start of Westside Bridges Retrofit Project

The San Francisco County Transportation Authority, in collaboration with Federal Highway Administration, Caltrans, Bay Area Toll Authority and the Treasure Island Development Authority, will begin construction on the West Side Bridges Retrofit Project on Yerba Buena Island.  The construction necessitates closure of Treasure Island Road south of Macalla Road, and of YBI's Bay Bridge on and off-ramps west of the Bay Bridge tunnel.

Multiple traffic circulation changes are associated with the Retrofit Project

The Forest Road detour road opening is the last in a series of recent traffic circulation changes on Yerba Buena Island enacted in support of the Retrofit Project.  Motorists must change their driving habits as follows:

When traveling to the Islands eastbound from San Francisco (as of June 26, 2023):

  • Utilize the new Southgate off-ramp located along the right side (#5 lane) of the eastbound lanes of the Bay Bridge (lower deck) immediately after the Yerba Buena Island Tunnel.
  • Motorists travelling to Treasure Island will follow the gently curving off-ramp to the stop sign at the intersection with Macalla Road
  • Proceed forward over the hill on Macalla Road until it intersects with Treasure Island Road and turn right to go to Treasure Island.
  • A Caltrans-produced video available here on You Tube demonstrates the recent changes to eastbound off-ramp access to Yerba Buena Island

When traveling to the Islands westbound from Oakland:

  • No changes to exiting circulation and off-ramp access.

When traveling from the Islands westbound into San Francisco (as of June 22, 2023):

  • Turn left from Treasure Island Road onto Macalla Road and proceed on Macalla Road until the marked Left Turn onto the I-80 Westbound Ramps on the east side of YBI. 

When traveling from the Islands eastbound into Oakland:

  • Continue to use southbound Treasure Island Road (on YBI) toward Hillcrest Road and the eastbound I-80 on-ramp until August 2nd.

Traffic circulation changes are extending MUNI 25-Treasure Island bus travel times

Beginning June 17, the 25 Treasure Island bus will see longer travel times due to this construction, which will affect frequencies. The line will run every 20 minutes on weekdays and every 30 minutes on weekends.

For more information, visit 

Sign-up for e-mail and SMS alerts for 25 Treasure Island service