With the current lack of holding facilities that don't block the main lines or single track at both Chippenham and Trowbridge, you have a major issue if operations get slightly out of step. Imagine a freight train coming up, slightly late, from Southampton and being held at Thingley on the "TransWilts" for 15 minutes to let an HST go through. No problem ... until you have another service (be it a freight, or the 17:02 Worcester to Southampton passenger train) needing to go down the TransWilts. As it currently stands, that extra service has to be held blocking the main line at Chippenham, and behind it would probably be the next London to Bristol HST.
So realistic TransWilts capacity is limited to - shall we say - occasional services unless reliabillity of operation is pretty close to perfect. It IS good to see that things are getting better on that front, and it's an area where improvements feed improvements.
With tracks arrange like this:
---------------
------ < *********** > ---------
---------------
------ < > ---------
---------------
*******
at Chippenham, you get much needed flexibility ... please forgive the ASCII trackwork.
Bearing in mind that the lines to Thingley are bidirectional, you can usually terminate the hourly (
) TransWilts in the short platform, which it will occupy for 20 minutes - arriving just before the London to Bristol service calls, and leaving just after the Bristol to London has passed, giving good connections all around and meaning that the two TransWilts units pass each other between Trowbridge and Westbury, and allow for a freight path every hour. Even if there's a waiting freight at Chippenham at the same time as the TransWilts unit, there's not a problem as there's a bidirectional platform, and the TransWilts unit could reverse at ANY platform.
Author
Logged
