c) Where derailment would be hazardous or costly, such as on steep
embankments and bridges.
For gaging, See AREA Portfolio of Trackwork Plans, Plan
Material. Relay rail of the same size as the running rail may be
used. Relay rail shall conform to the requirements of Military Specification
MIL-R-3911, Rail, Tee, Railway, Relayer Rail.
Track Construction. Use specifications as recommended in the AREA
Manual, Chapter 5, Part 4, Track Construction.