Research Will Smooth the Way for High-Speed Rail

11/2/2011 11:19:00 AM

Railroad Engineering Program Instructor J. Riley Edwards inspects closely spaced concrete ties designed to reduce differential transition movement at a recently upgraded Union Pacific crossing near Springfield, Ill. (photo courtesy of Timothy D. Stark)

Railway track transitions at bridges, crossings and stations frequently experience differential movement, or bumps in the track. This differential movement is especially problematic for high-speed rail infrastructure, because bumps at the transitions are accentuated at high speeds and can lead to car uncoupling, derailment, bridge damage or passenger injury.  A $1.7 million study by CEE researchers, funded by the Federal Railroad Administration, aims to minimize this differential movement and smooth the way for high-speed trains.

During the first phase of the three-year study, researchers led by CEE professors Erol Tutumluer and Timothy D. Stark will instrument and monitor newly constructed high-speed railway transitions along the Union Pacific railroad (UP) from Dwight, Ill., to East St. Louis, Ill.  This existing freight railway is being upgraded by UP to accommodate high-speed passenger rail and, when the upgrade is completed, will be a shared corridor for freight and high-speed rail.
The researchers will also retrofit and monitor existing Amtrak bridge transitions in the heavily traveled northeast corridor to better understand the causes of the observed differential movements and performance of various remedial measures.
“These unique field-recorded movements and applied stresses will be used to calibrate our state-of-the-art numerical models of track-foundation systems and ensure reliable prediction of future movement,” Stark says.  “In addition, the development of field-calibrated numerical models will lead to expertise and analysis techniques that can be used to confidently predict the future performance of new designs and retrofit measures.”
Differential movement at railway transitions can occur because of differences in track system stiffness, foundation type, track ballast, or rock settlement from fouling or degradation, as well as settlement of the approach embankment fill and the native soils underlying it, Stark says. This research will build on extensive prior research by Tutumluer and Stark on the settlement of pavements and railroad track structures due to traffic loading, as well as studies of differential movements at highway bridge approaches for the Illinois Department of Transportation. The researchers anticipate that high-speed rail lines will be able to utilize technologies similar to those that are used to mitigate differential movement at highway bridges.
“This is truly a unique project because the research team will be working directly with Amtrak and Union Pacific on the design and remediation of high-speed rail bridge approaches and then monitoring their performance to assess long-term effectiveness,” Tutumluer said. “Through this collaboration between the project team and railroad industry partners, this project will have a direct and positive impact on passenger and freight rail operations in joint corridors in the U.S. and will ultimately result in improved safety, increased speed and network reliability, and improved management and maintenance of mixed use tracks by reducing capital and life-cycle costs.”
This study, “Mitigation of Differential Movement at Railway Transitions for U.S. High Speed Passenger Rail and Joint Passenger/Freight Corridors,” is funded by the Federal Railroad Administration under the direction of Cameron Stuart. Collaborators include railroad industry partners Union Pacific, and Norfolk Southern and contractors Nicholson Construction Company, Geopier Foundation Company, and Tensar International Corporation.