Current reconstruction methods for older transit track systems are costly and require lengthy disruptions of service. Alternative methods of track reconstruction that allow work to be completed efficiently during off-peak periods or reduce the total time for reconstruction would improve service and yield economic benefits.

A number of methods for expediting track reconstruction by using precast concrete systems have been introduced in recent years. The use of precast concrete systems for track reconstruction can reduce construction time and minimize adverse impact on service while realizing economic and other benefits. However, research is needed to evaluate these systems and develop better procedures for track reconstruction.

The ultimate objectives of the research contemplated under TCRP Project D-3 are to identify and develop optimized precast concrete systems that allow efficient reconstruction of older tunnel track systems and to develop procedures for their installation. The research will focus on the installation and related design of precast concrete systems to replace existing track in tunnels. It will not deal with the removal of the existing track, but it will address any preparation needed prior to installation. These objectives will be accomplished in a series of projects. The first of which is TCRP Project D-3A.

The research under TCRP Project D-3A evaluated precast concrete systems used for tunnel track reconstruction, proposed improvements to these systems, and developed a work plan for evaluating the suitability and long-term performance of the proposed improvements.

Status: The project has been completed, and the agency's final report has been received. The report provides a review of practices pertaining to tunnel track reconstruction methods and identifies potential systems that merit further evaluation. However, because evaluating the long-term performance of these systems would require the removal and reconstruction of a section of track, substantial involvement by a transit agency and others involved in the design, construction, and replacement of track structure, and a large investment, no follow-up research was recommended as part of this project.