|Length:||3.2 miles (5.1 km)|
|Meets:||A5, B5107, A55, A487, B4547|
|Route outline (key)|
The A4087 is a short road in north Caernarfonshire.
The route starts on a one-way loop by the station in Bangor. Unusually, the roads making up the loop are numbered as if they were all two-way; the A4087 starts on the A5 and heads east then south to traffic lights. From here the B5107 continues round the loop, taking A5 traffic heading out of town to the third corner, where it meets up with inbound traffic which uses the fourth side of the loop, the only one to be numbered A5.
The A4087 proper starts at the traffic lights on the B5107 and immediately goes under the railway line. It heads southwest through the suburbs of Bangor along Caernarfon Road, which soon runs along the bottom of a valley. The road passes an out-of-town retail park then becomes D1 as it interchanges with the A55 at J10. Here, the two west-facing slip roads both meet a roundabout but the east-facing slip roads simply join the A4087.
This incarnation of the A4087 came into being in the 1960s when the A487 was rerouted away from Snowdonia and then extended to meet the A5. The extension took over the northern end of the A499 and that part of the road not taken over by the A487 became the A4087. The road originally ran the full length of Bangor High Street to meet the A5 by the harbour; when the High Street was pedestrianised the road was cut back to its present starting point on the southern side of the city centre.