Now that I have half a year's data for Monday to Friday trains that call at / were supposed to call at Melksham, I've been corellating the reliability record.  The format I've employed here is in response to a request that I've just received for such data as input to an ORR (Office of Rail Regulation) request for data.

SERVICE - Swindon to Westbury

OPERATOR - Wessex Trains (to 31.3), First (from 1.4)

NATURE OF DETRIMENT - Cancellations. Alternative arrangements for through passengers via an awkward and delaying change at Bath, and for local passengers via substitute road transport which means an arrival rarely less that 60 minutes late, or by waiting for the next train over 4 hours later.

FREQUENCY OF OCCURRENCE - 3.1% of Monday to Friday trains over 6 month period from 1st February to 31st July 2006. Detailed list follows.  Frequency rises to a cancellation rate of 6.2% on the busiest train of the day, which is scheduled to call at Melksham at 18:09.

ALTERNATIVE ARRANGEMENTS - Usually, but not always, an alternative bus has been arranged, with delays to passengers normally in excess of 1 hour.  I have also been advised by national rail enquiries, when the 17:02 service was cancelled, to await the next service at 21:33.  On occasions, travellers from Swindon to Melksham have been given a taxi, and at other times told to take the train to Bath and change there (presumably into the X72 bus).

EXPLANATION - various. "Usually due to a lack of servicable trains; problems at depot with repairs" was offered as a blanket reason for the high cancellation rate. Also shortage of train crews, train failures and hitting a deer on the line have been given as explanations on specific occasions.

The following is extracted from a log of Monday to Friday train services between Swindon and Westbury, taken from the on line departure board.  Note that it only lists trains that I am certain were cancelled; on a further 60 occasions, the board has stated "No report" which indicates one of:
        a cancellation
        a train that's so late it has not left Swindon or Westbury when due at Melksham
        a failure of the on line departure board system or monitoring equipment

823 out of 1281 trains monitored were shown as "on time".

I have NOT collected weekend data.  For the MAJORITY of weekends over the last year, at least some trains have been replaced by buses due to engineering works and it has not been practical to set up the systen to monitor running trains on a weekend by weekend basis.

CANCELLATION LOG

05:52
7th April
4th July
(2 out of 123 = 1.6%)

06:56
7th April
4th July
(2 out of 123 = 1.6%)

07:45
10th February
14th February
23rd March
20th April
(4 out of 129 = 3.1%)

09:12
10th February
14th February
23rd March
20th April
(4 out of 129 = 3.1%)

13:35
10th February
(1 out of 127 = 0.8%)

14:49
10th February
24th April
(2 out of 128 = 1.6%)

17:02
22nd February
24th February
29th March
20th April
8th June
11th July
17th July
28th July
(8 out of 129 = 6.2%)

18:09
22nd February
24th February
29th March
20th April
8th June
11th July
17th July
28th July
(8 out of 129 = 6.2%)

21:33
23rd February
3rd March
28th March
26th April
(4 out of 126 = 3.2%)

22:37
23rd February
3rd March
28th March
26th April
(4 out of 127 = 3.1%)

Overall - 39 cancellations out of 1270 = 3.1% - and remember these are only the trains that I'm sure were cancelled; there are additional "no show"s.

My defintion of a cancellation is a train that fails to run - in this case - through Melksham and provide the scheduled service.  It differs from the operator's definition which describes a train as cancelled if it fails to reach its final destination.  On some recent occasions, the 18:09 departure from Melksham has started at Westbury and run to Southampton; this truncated service is described as "revised" rather than "cancelled" by First Great Western, but shows as "cancelled" in my listings above.

Yes indeed ... it all points to a squeeze on resources at the busiest time of day. Interestingly, I came up with this analysis in response to a request:

"This morning I had a meeting with ORR's Competition Team in connection with their market study of ROSCOs.  This study is the first stage in responding to the Department for Transport's formal request asking the ORR to refer the passenger rolling stock leasing markets to the Competition Commission for a detailed investigation."

ORR - Office of Rail Regulation
ROSCO - Rail Operating Stock Company

I can pass on other reports too, or put you in touch if you want to make direct input ... the format requested is ...

"A response in the following form would be useful:

• Service (e.g. 1708 from Commuterton to Bigtown on 11/06/06)
• Operator (e.g. Greater Midland)
• Nature of detriment (e.g. 3 Passengers unable to board regular two-car Class 149 at Middleplace due to over-crowding)
• Frequency of occurrence (e.g. Common on Mondays and Fridays throughout school term)
• Alternative arrangements (e.g. Passengers advised to wait for through service following one hour later or to travel by way of connection at Remote Junction)
• Any explanation offered (e.g. Train unit failure)

A scant example is better than none at all."