Technology Digests / Revenue Service Test of a No. 24 Modified Heavy Point Spring Rail Frog

TD25-018

September 30, 2025
Authors
  • Ekrem Koç
  • Benjamin Bakkum
  • Duane Otter
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Key Findings

  • The modified heavy point spring rail test frog has been performing well with over 100 MGT of accumulated traffic tonnage.
  • After accumulating 130 MGT, the control frog was removed from service, likely due to ride quality issues for the high-speed passenger trains.
  • Compared to the control frog, the test frog showed a 67 percent reduction in head height loss at the point per 100 MGT.
  • On both frogs, lateral wear on the gage side of the main wing (spring rail) was greater than the rail head wear at the same location due to spring rail operations.
  • The diverging wing wheel transfer zone on the test frog was approximately 5 inches shorter as a result of the wider flangeway implemented on the test frog.

Revenue Service Test of a No. 24 Modified Heavy Point Spring Rail Frog

As part of the Revenue Service Testing Program, MxV Rail engineers evaluated the performance of a modified heavy point spring rail frog on Union Pacific Railroad (UP). A heavy point frog requires strict manufacturing and installation tolerances, including track gage, face gage, check gage, and flangeway width, to meet all Federal Railroad Administration (FRA) Class 6 track safety standards. This Technology Digest presents the test results for a modified No. 24 heavy point frog on a Class 5 track with 90-mph passenger traffic (upgraded to Class 6 track with 110-mph passenger traffic in 2023) and 60-mph freight traffic and 15–20 million gross tons (MGTs) of annual tonnage. BACKGROUND This test was initiated in 2017 to evaluate the modified heavy point frog design. Along with this modified frog, a No. 24 standard heavy point spring rail frog (installed under an FRA waiver) on the same line under similar tonnage was also…