When higher speeds become possible, what do you do with the timetable?

[Western 52]

Suppose a TOC gets some nice new trains which perform better than the ones they have replaced, and the route is suitable for higher speeds. Maybe class 197 replacing class 150 or similar.

Does the TOC:-

a) improve the timetable to take advantage of all the additional performance now possible, or

b) keep the timetable as it is and use the extra performance to improve timekeeping and reliability, or

c) take a half-and-half approach and make some timetable improvements, leaving increased margin for reliability?

I know in the real world there are many other constraints, such as other traffic and connections, but let's assume a simple route without too many external factors.

 

[The exile]

If I were doing the planning and ignoring all other constraints (which in this instance are completely unknown to us!), my preference would be :

b) for the transition period and at least one full timetable period after - to allow for bedding-in , teething troubles etc - then
c) - unless there was already so much slack that any more would be ridiculous.

 

[The Planner]

You tend to wait until every schedule is using the new traction and refine the running times, as new traction SRTs are modelled first. Also depends on if the dwells can be kept the same, if not you take the performance gain and stick it in the dwells. There are plenty of other factors as well, is the traction bought to unlock journey time improvements, for capacity but performance gain is a freebie, how much time does the traction change give you, if its say only a couple of minutes then you may just leave it as it is.

 

[edwin_m]

Sometimes a faster schedule isn't possible due to other conflicts. For example a few years ago I looked at improving speeds and frequencies on the Heart of Wales line, but with multiple passing loops it tended to work out that if trains passed at one of them, they would miss at the next one and the time gained was wasted sitting at the loop.