Talking of wheel flats, if
a carriage wheel is (say) 30 inches in diameter it will revolve
672 times for each mile travelled. If the journey from Crewe
to Holyhead and back is 212 miles then the wheel will hit the
track 142,500 times during that return journey. Similarly, if
Crewe to Birmingham and back is (say) 100 miles the flat will
hit the track 67200 times. Therefore, on the current 37/4 diagram,
a vehicle with a flat will strike the rail top over 352,200 times
a day. The train I rode today had two flats which means that
the track was hit over 700,000 times during the day's operations.
How do track and bearings tolerate such wear?