M40 - A404 Comments

The grid-locks are often as not caused by drivers jumping the lights subsequently blocking entrances as they wait to enter their exit. I would propose that the WHOLE round about is made into a box junction supported by appropriately placed (and sign posted!) box junction cameras.

Perhaps a magic roundabout like junction one would have been better.

My main gripe with his junction is with the drivers that don't understand the lane rules as you exit the junction for the southbound A404. All three lanes can be used for entering the A404, but ONLY the left hand lane is for turning left towards Marlow Bottom. So many drivers cut across from the middle lane turning left towards Marlow Bottom. One day they will be T-boned by a car going straight across.

"In the longer term we will link the signals to the Reading Control Room so that we can remotely monitor and change the timings to suit traffic conditions. This remote control was always intended but we have had problems with a telephone link."

I emailed the DfT last night after spending 90 mins to go 700 yards up the A404, around the roundabout and join the eastbound M40.

I have known this roundabout for years, and although the old design was pretty hideous, the new junction has new issues, as described in my email below:

"The problem is basically that there is no protection of the exit junctions and crossing points from the inner loop and roundabout to the surrounding connected roads, hence when the roundabout becomes busy the traffic reaches a point when the entire roundabout becomes a solid loop.

"I cannot see why there cannot be box junctions (monitored by cameras) to protect the major exits on the roundabout and control the waves of traffic allowed onto the roundabout. Although these would obviously be an extra cost, the box junction painting in itself would cause most drivers to think again before blocking the roundabout exits, and would be significantly cheaper than any changes to the light phasing or additional roadworks."

Unfortunately, since this junction has been completed, it regularly goes into gridlock. Lorries coming off the M40 south heading onto the A404 via the new roundabout block the traffic from flowing around, allowing only a few cars through the lights at a time. The junction needs yellow boxes painted onto it, or a complete re-build... But let's face it, they would probably make it even worse again.

The work that is mentioned is now complete. A hige slipway now cuts across the roundabout, bypassing the A4010, the road to the north and the A404 north. It's a lot easier to get from the A404 from Maidenhead onto the M40 towards London.

A new slipway now goes from the A404 from Maidenhead, under the road to Marlow bottom and then onto the M40 towards Birmingham. In short, traffic from the A404 can now be routed onto the M40 (both directions) much easier.

Is the fact that the M40 is down to two lanes through the junction, often resulting in long queues, ever going to be sorted? There would seem to be enough room if the hard shoulder is 'lost' through the bridges, as happens in some places elsewhere where widening has taken place, eg M25 j9 to 8.

Surely the fact that the M40 is reduced to two lanes at this point just for the duration of the junction has something to do with the chaos. The M40 was originally all two lane, then slowly turned into permenant roadworks to increase width to three and even four lanes - super - except for this 200-yard section which simply hasn't got the room without a complete rebuild of the whole junction and bridge.

I've watched this junction 'grow' from when it was a temporary end of the M40. The A4010 is to blame, being a 'bypass'. Plans were made to move the whole M40/A404 junction south, but this has now been superceded by a plan to burrow the A4010 through the roundabout to the southbound A404 to avoid conflict with the M40. I think we shall be seeing even more traffic lights!