Although one end is on the A38 and the other on the A303, the B3170 is little more than a local road.
It begins at a complex set of one-way roads and junctions on the A38
, and makes its way through the suburbs, passing houses and a couple of colleges on its way. At this point, like most urban B-roads, it is S2
, and carries a 30mph speed limit. Once it crosses the M5
and passes the main HQ for Heart Taunton (formerly known as Orchard FM), the limit increases to 40mph and is now rural in character.
After passing Taunton Racecourse (the road's only real cause for congestion, once out of Taunton
proper), the limit increases again to NSL
, and reaches the village of Corfe, small but signposted as there is little else along this road.
At the southern end of Corfe the B3170, more-or-less flat up to this point, begins to climb steeply up into the Blackdown Hills. The road winds through Whitford to avoid running straight up the hill before reaching a crossroads near the top of the ridge. The road descends slightly via Brown Down to the county boundary before bending round to meet the A303 at Stopgate.
The road originally continued to the now A30/A303 TOTSO junction near Upottery. This section was renumbered to A3079 when that route was created in the 1930s and has been A303 since 1933.