Figure 2-21. Track frog and guardrails.
b. Track Geometry.
Track geometry includes such items as gauge, line, surface, cross-level, superelevation,
and profile. Every member of a train crew should be on the lookout for signs that the track
geometry is unsafe. The simplest example is wide gauge that could cause a wheel drop
derailment. Wide gauge often exists where tie condition is poor, where several spikes in a row
are missing, or in curves. It can often be spotted by wear marks in one of the rails that only
extend partway across the rail. Several low joints in a row can be a serious track geometry defect
if it sets up conditions for harmonic rock and roll, and consequently a wheel lift derailment.
Although these and other types of cross-level defects are often hard to spot, if the train is
observed closely, its motion can often indicate a situation that should be reported. Figures 2-22
and 2-23 show how the measurements of gauge and cross-level are made.
2 - 22