Passenger numbers - diversions

[whole diary]

[grahame]

In putting together passenger numbers and uses of the TransWilts - in particular the section from Chippenham to Trowbridge - we've been taking a detailed look at regional traffic in 153 / 150 / 158 trains that have been "all stations", and indeed those number are towards the upper end of what we would have expected even in a "best case" scenario of everyone working well together (which has happened 90%+ of the time).

We have, though, overlooked traffic in High Speed Trains diverted over the line and on days of engineering of other issues on the Berks and Hants the TransWilts is every bit as important to those long distance journeys as it is to the regional stuff. 

How many journeys are we talking about?  My personal educated guess would be that we're looking at between 15 and 35 days, and with diversions ranging between a single train sent "via Melksham" on some of those days up to 16 trips (8 each way) at times.  In the lowest case scenario for those days, you're looking at perhaps 40 people on a single HST^▸ (High Speed Train (Inter City class 43 125 units)), and at the highest scenario you're looking perhaps at 16 x 200 passengers (average load) = 3200.

There are huge variations in my guesses.  If we said 8 "full diversion" days at 3,000, 6 part days at 1,000, 6 part days at 500 (single peak) and 6 days with 1 train diverted at 100, we're looking at 33,600 more journeys.  Add to that, I think, one summer Friday HST scheduled to run via Melksham and you're up, in very rough fingers indeed, to about 35,000 journeys.

Can anyone give me a more accurate figure or an amended guess ... or provide data or a data source which will help get get a better grasp on this traffic?