 Clearances for bridges
On Jul 17, 4:39 pm, Michael Bell <mich...@beaverbell.co.uk> wrote:
> What are the clearances for bridges and suchlike and for the boundary
> fence? Looking at the fences I get the feeling that there is some
> leeway!
>
> Michael Bell
>
> --
There are two separate issues to be considered here. The clearances
for bridges are related to the structure gauge and, on top of that,
the Design Kinematic Envelope, which represents an additional
clearance beyond the structure gauge to allow for movement of the
vehicle. The DKE varies according to linespeed and (ICBW here) type of
vehicle.
Historically, the boundary fence marked the limit of railway land
ownership, which can stretch beyond the tracks themselves, eg to the
top of a cutting or the bottom of an embankment. Furthermore, on new
railways, the boundary fence should, wherever possible, allow staff
working on the line under what are known as "Red Zone" conditions to
be able to reach a position of safety (defined as 1.25 m from the
nearest rail for linespeeds of up to 100 mph and 2 m from the nearest
rail for linespeeds 101-125 mph in the Personal Track Safety
Handbook).
The PTS Handbook defines a Green Z |