Date | Section of line | Miles/chains |
| 1 Jan 1837 | Total broad gauge mileage | nil |
| 4 Jun 1838 | Paddington - Maidenhead | 22m 43c |
| 1 Jul 1838 | Maidenhead - Twyford | 8m 18c |
| 30 Mar 1840 | Twyford - Reading | 4m 77c |
| 1 Jun 1840 | Reading - Steventon | 20m 44c |
| 20 Jul 1840 | Steventon - Faringdon Road | 7m 29c |
| 31 Aug 1840 | Bristol - Bath | 11m 43c |
| 17 Dec 1840 | Faringdon Road - Hay Lane | 16m 29c |
| 31 May 1841 | Hay Lane - Chippenham | 13m 57c |
| 31May 1841 | Swindon Junction - Kemble - Cirencester1 | 17m 75c |
| 14 Jun 1841 | Bristol - Bridgwater2 | 33m 20c |
| 14 Jun 1841 | Weston Junction - Weston-super-mare2 | 1m 38c |
| 30 Jun 1841 | Chippenham - Bath | 12m 73c |
| 31 Dec 1841 | Total broad gauge mileage | 170m 66c |
| Metric conversion: 80 chains = 1 mile; 5 miles = 8 kilometres |
| Note 1: | Cheltenham & Great Western Union Railway | |
| Note 2: | Bristol & Exeter Railway | |
| |
| | Locomotive Class | Number (+/-) |
| 1 Jan 1837 | Total locomotives | nil |
| | Unclassified engines | + 19 |
| | Star 2-2-2 | + 12 |
| | Fire Fly 2-2-2 | + 44 |
| | Sun 2-2-2 | + 20 |
| | Leo 2-4-0 | + 12 |
| | Unclassified engines withdrawn | - 8 |
| 31 Dec 1841 | Total locomotives | 99 |