Inter-regional Headcodes, North London Line

[JRHurst]

Can anyone explain how some 'inter-regional' headcodes work along the North London Line please...

Overground passenger trains from Clapham Junction to Stratford are 'L' - Anglia bound - but in the opposite direction are 'Y' not 'O'. And Stratford - Richmond trains are 'N' in both directions.

Tomorrow sees a Norwich - Wembley ECS move with a 'H' (5H72), but a Bow - Wembley runs 'M' (6M86).

Confused here.

Thanks, John

 

[NSE]

I know many places often avoid the use of O & I to avoid confusion with 0 & 1. Of course, railway staff know headcodes are formed ‘number letter number number’ but it may have something to do with it.

I don’t know about freight operations so that I don’t know.

 

[FGW_DID]

Can anyone explain how some 'inter-regional' headcodes work along the North London Line please...

Overground passenger trains from Clapham Junction to Stratford are 'L' - Anglia bound - but in the opposite direction are 'Y' not 'O'. And Stratford - Richmond trains are 'N' in both directions.

Tomorrow sees a Norwich - Wembley ECS move with a 'H' (5H72), but a Bow - Wembley runs 'M' (6M86).

Confused here.

Thanks, John

You would have to look at the specific WTT for that area. The inter-regional headcode letters may also be used for trains / routes specific to that particular WTT Area.
Each WTT area will have an index that will list the relevant Letters. See the link at the bottom for an example (PA).

Two examples in the WTT ‘PA’ area:

• the letter S (Scottish region in the inter-regional codes) is used for all class 2 trains from Paddington to Hayes & Harlington or Slough and vice versa.
• The letter L (East Anglia) is used for Class 2 trains between Reading, Didcot Parkway, Oxford, Banbury and Bicester Town and also Class 1 originating in the PB WTT area.

WTT PA index.

Network Rail WTT area index.

Edited to add link for Network Rail WTT webpage.

 

[zwk500]

Can anyone explain how some 'inter-regional' headcodes work along the North London Line please...

Overground passenger trains from Clapham Junction to Stratford are 'L' - Anglia bound - but in the opposite direction are 'Y' not 'O'.

This is almost certainly a specific deviation from the norm to mitigate the risk of confusion between a 'O' train running from Watford Jn to Clapham Jn/East Croydon.

And Stratford - Richmond trains are 'N' in both directions.

Technically Richmond NLL is within the Anglia Region.

 

[Harpo]

railway staff know headcodes are formed ‘number letter number number’

Not always. The Fenchurch St line used to use four numbers with the second number indicating routing.