|Distance:||3.3 miles (5.3 km)|
|Meets:||A89, B9080, B907, A90, A904|
|Old route now:||B907|
|Route outline (key)|
The B800 starts on the A89 at Newbridge, west of Edinburgh, and runs northwards alongside the River Almond to cross the B9080 (former A9) in Kirkliston before reaching Queensferry on the Firth of Forth, where it swings to the west to connect to the A90 Forth Bridge Road, although it originally continued ahead along what is now the B907 to end in the centre of town on the original line of the A904.
The main claim to fame of the B800 was that between 1970 and 2009 its northern section from just north of Kirkliston was upgraded to the A8000 (although some early maps show the southern section upgraded as well) as a result of the M9 spur, thus making the road the main route south of the Forth Road Bridge. Busy dual carriageway from the M9 to the bridge terminated on a roundabout just north of Kirkliston, and traffic to the bridge was forced to take this humble S2 up to the bridge. The result was inevitably terrible congestion.
Eventually, the M9 spur was extended past the old roundabout without any access to the quiet Kirkliston road. Having once been linked directly to one of the busiest routes in the UK, the B800 has thus returned now to being once again a peaceful, local B road, although the A8000 did not become B800 again for a couple of years after the M9 spur was extended and the junction here closed. The B800 now ignores the M9 spur and heads north to cross over the A90 west of the Scotstoun Junction, heading into the suburbs of South Queensferry. It comes to a roundabout beside Tesco and then turns left to another roundabout at Echline Junction just south of the Forth Road Bridge; the A904 continues out the other side.