Dangerous blind spot, made worse by cars overtaking

On the slip road, from the roundabout with the A4, down to the A404M, heading towards the M4: as you merge with the dual carriageway, there is a blind spot, owing to the curve in the main carriageway. The blind spot is made worse when other cars, speeding usually, try to overtake on the slip road, taking the right hand of the two lanes on the slip road, even trying to overtake as close as the end, and try to cut in, and in doing so also block your view of the oncoming traffic, making you have to stop. This bad driving makes a dangerous point even more so. A solution would be to amend the road markings, to make the two lanes on the slip road merge into one, and then also curve in a particular way, so as to bring you more parallel to the main traffic, to assist mirror vision. This happens more than you'd think, as fast drivers want to speed, after having to go to a limit on the A4.