The A1245 follows the old route of the A130 as it passes between Wickford and Rayleigh.
The road starts at a roundabout on the A130 near Benfleet, where all three left turns are given their own filter lanes. The A1245 heads north along a road that is a 3-lane dual carriageway (D3) for part of its distance, before reaching a grade-separated junction (GSJ) on the A127. The A130 no longer has a junction with the A127, so this is the route used; some maps even claim it to be a spur of the A130. There is a debate as to whether this section is primary, with maps and signs disagreeing.
The A1245 continues north, now certainly non-primary although a 2-lane dual carriageway (D2). It goes over the Great Eastern line from London to Southend before a short detour east leads to a roundabout junction with the A129. The old A129/A130 crossroads was a short distance to the west and is still marked with a pub.
The D2 continues north into Rawreth and then narrows just in time to reach the southern end of the Battlesbridge bypass. The road skirts the village to the west, crossing the narrow River Crouch and the Southminster Branch Line en route. A roundabout is soon reached where the old road from Battlesbridge reaches us again. The A1245 ends here, where it meets the A132 and returns to the A130. The roundabout is part of a bizarre GSJ for the A130, although the road layout suggests that something else was planned regarding the A132.