Tom Anderson wrote:
On Tue, 2 Oct 2007, Clive D. W. Feather wrote:

In article , Tom
Anderson writes

"on the Moorgate Welwyn Garden City / Hertford North routes contra
peak services (i.e. northbound until 0900 and southbound after 1600)
are only 2 tph."

Christ! How the hell does that work? Do most of the trains run ECS
back up north?


The peak arrivals run ECS back up to the northern termini to provide
another with-flow service.


Okay, that's what i suspected.

How much time does that save over running in service?


12.5 minutes.

[Moorgate to WGC: 46 minutes in service, 33.5 minutes ECS.]


Okay. Assuming that the run in service back down is also 46 minutes, and
assuming zero turnaround time at either end, then the length of a
half-ECS cycle (is this what they call a diagram?) is 79.5 minutes, and
a fully in-service cycle is 92 minutes, 15.7% longer.

But Clive's figures only apply to Moorgate - WGC. The original document
was also talking about the Moorgate - Hertford North route, where the
trains usually start from either Stevenage or Letchworth. The saving there
may be even greater. (And now I understand why I often see one of
these units running empty on the down slow at Stevenage in the
mornings.)