It's longer than I guessed, then.
Not sure. It may be to just accommodate 4 of a 5 car set.
It's on network Rail's list of platforms to go to 5-car length. The full list for project W009 (West of England
DMU▸ Capability, oddly) is:
Operational length | No of platforms | Stations and platforms |
| to be extended | to be extended |
1 car (23m vehicle) | 2 | Dilton Marsh – Platforms 1 and 2. |
3 car (23m vehicle) | 1 | Melksham - Platform 1 |
5 car (23m vehicle) | 7 | Bradford on Avon – Platform 2 |
| | Freshford – Platforms 1 and 2 |
| | Lawrence Hill - Platform 2 |
| | Stapleton Road – Platform 1 |
| | Trowbridge – Platform 1 |
| | Warminster – Platform 2 |
6 car (26m vehicle) | 3 | Kemble – Platform 1 |
| | Stonehouse – Platforms 1 and 2 |
|
They also note that:
"Works to address stepping distances are only required at specified stations; Freshford Platform 2 and Stonehouse platform 2."