| British Rail Brake Standard Open | |
|---|---|
| In service | 1955– |
| Manufacturer |
Mark 1: BR Doncaster, Wolverton and Gloucester RCW Mark 2: BR Derby |
| Family name |
British Railways Mark 1, British Rail Mark 2 |
| Constructed | Mark 1: 1955–1963 Mark 2: 1966–1974 |
| Number built | 340 |
| Fleet numbers | 9200–9539 |
| Capacity |
Mark 1: 39 Mark 2/A–D: 31 Mark 2E/F: 32 |
| Operator(s) | British Rail |
| Specifications | |
| Car length | 66 ft 0 in (20.12 m) |
| Width | 9 ft 3 in (2.82 m) |
| Height | 12 ft 9 1⁄2 in (3.90 m) |
| Maximum speed | 90–100 mph (145–161 km/h) |
| Weight | 33 long tons (34 t; 37 short tons) |
| Train heating | Steam, Electric or both |
| Bogies | BR1, Commonwealth, or B4 |
| Braking system(s) | Vacuum, Air, or both |
| Coupling system | Drop-head knuckle coupler on draw-hook |
| Track gauge | 4 ft 8 1⁄2 in (1,435 mm) standard gauge |
A Brake Standard Open or BSO, is a type of railway carriage used by British Rail. Both Mark 1 and Mark 2 types were built. Each consists of a standard class open passenger saloon with a centre aisle, a guard's compartment with hand brake and a lockable luggage compartment.
A number of Mark 1 and Mark 2 BSOs were converted to Brake Standard Open (Micro-Buffet) (BSOT), and fourteen Mark 2 BSOs were converted to Driving Brake Standard Open (DBSO). A number of BSO and BSOT coaches have been preserved, and some are still in use on main line charters.