Route availability
Route Availability (RA) is the system by which the permanent way and supporting works (bridges, embankments, etc.) of the National Rail network of Great Britain are graded. All routes are given an RA number between 1 and 10. A route availability of one (RA1) is the most restricted. 10 is the most open.
Rolling stock is also given an RA (again between 1 and 10) and the RA of a train is the highest RA of any of the supporting elements. The RA is mainly about the axle load of the vehicle, although axle spacing is also considered. In practice it is the locomotive which decides where trains may operate, although many high capacity four axle wagons have high RAs when fully loaded. (When considering the operation of trains the loading gauge must also be considered.)
Route Availability Media
With its relatively high axle load, the Class 67 locomotive has a somewhat limited Route availability of 8
A Class 86/2 No. 86 252 at Birmingham New Street railway station. This class has a Route availability of 6.
A Class 37 in British Rail large logo livery at Muir of Ord railway station, 1988 with a medium Route availability of 5.
Class 14 No. D9526 (as preserved) at Williton on the West Somerset Railway a low axle load and less limited R.A. of 4.
Class 01 shunter 01002 inside the shed at Holyhead Breakwater. The withdrawn loco 01001 is just visible at the rear. They had an RA of 1, and thus had the fewest axle load related restrictions put upon them.
