ABSTRACT
Compared to highway bridges, Light Rail Transit (LRT) bridges are subjected to additional forces/deformations caused by rail-structure interaction (RSI). Frequently, the impact factor used to account for dynamic effects caused by a passing train needs to be validated through rolling stock analysis (RSA). The RSI effects are typically aggravated by using Continuous Welded Rail (CWR) with direct fixations, as the CWR is a popular system due to maintainability, safety, and passenger comfort. This paper outlines the different RSI analyses required for the design of LRT Bridges and provides design recommendations.The existing Myrtle Avenue Bridge, also known as the Fresh Pond Bridge carried two MTA Subway M Line tracks over New York and Atlantic Railway. This was replaced with a three through-girder bridge. Limited allowable interruptions below the bridge and a gas main dictated the construction of the new abutments behind existing ones. Micro-piles were used to limit the vibration. Piles were installed only during weekends to expedite construction. This paper discusses the design and construction challenges and solutions adopted for the new bridge.
