Within the main railway network, there is a standard classification of rail services comprising of a headcode, which comprises of three numbers and an alphabet (e.g. 1Z99).
In the London Underground, there are different system of classifying tube services, made up of three numbers (e.g 366). I notice this when I read the Underground's Working Timetable (WTT), especially when some services have a 'D' after their number or any letter before it.
This is something I do not fully understand on how it works. Could someone please explain how this form of headcoding works?
In the London Underground, there are different system of classifying tube services, made up of three numbers (e.g 366). I notice this when I read the Underground's Working Timetable (WTT), especially when some services have a 'D' after their number or any letter before it.
This is something I do not fully understand on how it works. Could someone please explain how this form of headcoding works?