Green Line IMT Double Track

About Project

The Green Line IMT Double Track project was part of a $40.9 million grant from the Transit and Intercity Rail Capital Program (TIRCP) to reduce greenhouse gas emissions, modernize MTS systems and improve safety.  The Green Line terminates at 12th and Imperial Transit Center where Light Rail Transit (LRT) vehicles terminate on the bayside platform and turnback.  The Green Line will be double tracked in the area with the addition of a new double crossover to provide greater operational flexibility and increase the trains available to move people for operations during special events such as Comic-Con.

Project Scope, Successes

Pacific Railway Enterprises (PRE) provided transit signal final design, vital and and non-vital train control and station communications final design, technical specifications, cost estimates and bid analysis for the project.  The signal improvements for the project included constructing two new rail cases, new signal indicators with pushbutton request, power switches, TWC loops and impedance bonds.  New ElectrologIXS microprocessors were design to control the new rail case locations.  The project also included removal of one rail case and modifications to an existing rail case.

Within the project limits, MTS fiber optic cable transitioned from aerial on catenary to underground to serve the bayside platform.  The new track alignment created conflict with existing Overhead Catenary System (OCS) poles that contained aerial fiber.  The train control communications improvements analyzed the most cost-effective way to modify the aerial fiber to remove the existing rail case from the communications network and add a new rail case to the network.  The involved pullback, reuse of fiber and determination of new splice points.  Care was taken to avoid construction impacts to third party fiber belonging to the Port of San Diego.  The final plan was supported with multiple field verification visits as the overall design concept solidified.

The new track alignment also required the existing station platform to be narrowed and become a center platform.  PRE could provide cost effective engineering here based on its existing understanding of MTS station platform systems.  The station systems design coordinated with other disciplines, such as electrical, utilities and civil to determine the best placement for a common duct bank that facilitated complex construction phasing for the platform modifications, with the goal of maintaining platform operations during construction.

Project Highlights

• Produced 100% level design drawings, specifications and estimates
• Utilized ElectrologIXS platform for improved long term support and increased competition
• Coordinated with the design team to determine optimal fiber optic cable modifications
• Coordinated with utilities, electrical and civil to determine common duct bank placement
• Created add alternative option drawings