Eureka Curve Tunnel Work

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Project Introduction

To take advantage of the Muni Metro service not running in the subway due to COVID-19, the SFMTA has been maximizing the work window to maintain the track system and infrastructure in the subway. Today, we are glad to announce the completion of the Eureka Curve Tunnel Work that has replaced track ballast, crossovers and switches between Castro and West Portal Station. Currently we are certifying that the automatic train control infrastructure was reinstalled successfully and continuing other maintenance work in preparation for the return of more rail service. 

With the Eureka Tunnel work completed, the construction related traffic and parking restrictions have been lifted on Market, Castro, Diamond and Collingwood streets. Occasionally, momentary traffic control may be required to allow the movement of construction materials for other tunnel work.

While we continue the critical maintenance work to enhance reliability and resilience of the subway, more rail service is coming back. By May, the SFMTA plans to restart more Muni Metro rail service, extending the T Third Metro rail route between Sunnydale and West Portal, and bringing the full N Judah Metro rail route back into service between 4th and King (CalTrain) and La Playa (Ocean Beach).

Project Timeline
November 30, 2020
Construction begins
February 2021
Anticipated project completion
Project Status
  1. Implementation / Construction
Predicted Completion
February 2021
Bus Routes and Rail Lines
Project Details, History or Features

In 2019, we completed a major project in the Twin Peaks Tunnel that included seismic upgrades and major track and other infrastructure overhauls. Additional work in this crucial section of trackway still needs to be done to improve the quality of the system and reduce the potential for disruptions to service in the years to come. 

Starting Monday, November 30, construction crews will begin maintenance work inside the Twin Peaks Tunnel. Most materials and equipment will enter the tunnel at the Eureka Curve – the area on Market Street between Diamond and Collingwood streets. This work addresses drainage issues related to the degradation of the track ballast - the rocky bed underneath the tracks that stabilizes the trackway. Crews will be replacing the ballast and work on track alignment.

This work is occurring alongside the replacement of overhead splice connectors, overhead wires, track fasteners, switch machines, rail grinding and trackway adjustments throughout the tunnel.

The Eureka Curve Tunnel work is anticipated to take approximately three months. We plan to wrap up in February 2021.

Construction work is scheduled for Monday to Saturday, from 7:30 a.m. to 8:00 p.m.; hours are subject to change based on construction needs. No night work will be performed in the public right of way and will be limited to within the tunnel. Heavy equipment will be entering through West Portal subway tunnel only during the morning, for about an hour. We do not anticipate any parking impacts or traffic lane changes near West Portal Station.

As we perform this work, some parking will be temporarily restricted, and traffic lanes will be modified in the construction zone. These temporary changes are:

  • One lane street closure in each direction on Market Street between Diamond and Castro Street
  • Parking will be temporarily restricted on Market Street between Diamond and Castro Street  
  • No access to Market Street from Collingwood Street. Local access from 18th Street will be provided 
  • Material and equipment staging on both sides of Market Street between Diamond and Collingwood Street.  
  • Heavy equipment will enter through West Portal Station tunnel most morning for about an hour. We do not anticipate any parking impacts or traffic lane changes near West Portal Station.
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