Transit Projects

Red Line Floating Slab Project

The Red Line track from Harvard to Alewife sits on concrete slabs floating on rubber disks that absorb noise and vibration from trains. Years of water infiltration into the tunnel has resulted in corrosion and cracking that must be addressed in order to maintain safe and reliable Red Line service.

In addition to six 2014 weekends in which some Red Line service is replaced with shuttle bus service, the Floating Slab Project has planned eight to nine additional weekend shuttle bus diversions scheduled each year for 2015, 2016, and 2017. These scheduled shuttle bus replacement diversions have been scheduled each year in anticipation of maintaining a state of good repair within the area of the Floating Slab. During the course of the Floating Slab Project, MBTA work crews will be removing and replacing corroded concrete slabs as part of a project partially funded by the American Recovery and Reinvestment Act. In addition to correcting problems with the floating slab structure, the project will involve the replacement of track and third rail. Workers will also address leaks in the tunnel to prevent further deterioration. 

Weekend Bus Replacement

Due to the complexity of this project, work cannot be completed during the short overnight period when service is not operating. Materials can only be brought to the job site by rail and the nearest access point is more than two miles away near the Longfellow Bridge. Also, the concrete requires a certain period of time to settle before train service can begin. 

As a result, buses will replace Red Line trains between Harvard Square and Alewife Stations during eight to nine weekends in each year of 2014, 2015, 2016, and 2017.

For shuttle updates and information, please check Red Line service advisories here.

Related Documents

Floating Slab Presentation - 10.16.2012  PDF  Word

Photos of the Project

Floating Slab Supervisor and Track Engineers Floating slab  Floating slab Floating slab Floating Slab Gradeall Floating Slab Ballast Removal Floating Slab  Replaced Slab  Secondary Slab Prepped Slab  Floating Slab  Cement Slab  New Cement

Last Updated: December 2014