|Distance:||3.5 miles (5.6 km)|
|Meets:||A329, A329(M), A4|
|Route outline (key)|
The route starts at a hamburger roundabout on the A329 at Loddon Bridge, Winnersh, as a northern extension of the B3270. After passing under the Reading to Wokingham railway line it reaches the western terminus junction of the A329(M) and from here it continues west along what was until 1997 the final part of that motorway.
The ex-motorway section is non-primary D2M, and has hard shoulders which are hatched out. Less than 2.5 miles long, it still looks like a motorway, with marker posts and emergency phones. About 0.5 miles from its terminus, a (very narrow) bus lane appears on the westbound hard shoulder – and it is for this reason that the road has been reclassified as the A3290.
The numbered road ends at a grade-separated junction with the A4, where almost all traffic turns off: either for Reading or heading towards Maidenhead. The through route continues northwestward, however – as an unclassified road which ends at a roundabout junction serving a business park. If you head back from this roundabout you may observe that on the gantry sign on the approach to the GSJ the overhead lane marker for the A4 is black-on-white, but those for the A3290 remain white-on-blue – nearly 20 years after the route ahead ceased to be a motorway.