|Location Map ( geo)
|25.3 miles (40.7 km)
|M40, A40, A329, A4129, B4011, B4445, A41, A4156, A413, A4157, A4146
|Old route now:
|A4012, A507, B530, A5141
|Route outline (key)
The A418 is a medium-distance A-road linking Oxford to Aylesbury and Leighton Buzzard. In its original form it was much longer, extending right across the 5-zone to pass through Woburn and Ampthill, before terminating in Bedford on the A6.
Section 1: Wheatley – Aylesbury
It starts its journey at the Sworford trumpet interchange at Wheatley on the A40. It has the unusual feature of having two junctions with the M40 within 1/2 mile: the end of the A40 spur here and junction 8A shortly afterwards. Also it is part of a multiplex with the A40 here, the A418 taking numbering priority. Prior to the building of the Wheatley bypass in 1962-63 it ended right before the abutment of the old Oxford - Princes Risborough railway line bridge. The disused line will follow us alongside until we reach Thame. The old section of road can still be walked down, behind a set of gates, just after the new junction with the A40.
About half a mile after the main M40 junction the A40 turns off to the right on a new-build road for non-motorway traffic, built as the original slip road was closed when the M40 extension was opened. We then head into Tiddington, a small village that has been asking for a bypass for many years to no avail. After Tiddington the road gently twists and turns its way for 5 miles towards Thame. We arrive at Thame at the roundabout junction for the A329 (former B4013), which now ends its journey from Bracknell way. Before the bypass was built the A418 made its way through the small market town, with its narrow streets via two TOTSOs to emerge at the other side. The Thame bypass was opened in 1980. It seems to be over-engineered but this was due to plans for a major route from the East coast to the M40 and on to Swindon that has yet to come to fruition.
At the roundabout junction with the A4129, B4011 and B4045 the road reverts to its previous standard, slightly narrow and twisty. We are now heading off towards Aylesbury. At the top of a small hill a right turn heads off to the town of Haddenham; the A418 appears to be a bypass of the town but actually it isn't. We work our way through Stone and then after a sharp 90-degree left turn we head into the outskirts of Aylesbury.
Section 2: Aylesbury – Wing
After multiplexing around Aylesbury town centre on the A41, the A418 continues on the town's ring road for a short distance, to a roundabout with the A413. Turning left at the next roundabout and right at the mini-roundabout after that, the A418 rejoins its old route. Aylesbury almost seamlessly becomes the village of Bierton, and then, other than the small hamlet of Rowsham, the road isn't built up at all until Wing. At Wing, the road sharply turns left, then right again, causing a bottleneck on the Aylesbury to Milton Keynes route. Plans to bypass the village have existed for a great many years, very nearly getting built in the late-1980s, then causing great controversy in 1991, when the design specification was significantly increased, due to being part of a major new build trunk route (that fell flat with the Wing bypass plans). Wing, incidentally, was proposed at one time to be the site of London's third airport, so it is possible that the A418 would have been diverted and/or heavily upgraded to serve that. At the north end of Wing, the A418 terminates on the Linslade Southern bypass (formerly A505)/Western bypass (A4146) junction.
At its southern end, the A418 is not much changed from its original route. The construction of the M40 saw it gain two junctions with that road; the trumpet interchange where it meets the M40's Oxford spur, and the roundabout junction with the mainline of the motorway itself.
A bypass of Thame was completed in 1980, removing the road entirely from the town. The first half of the original route through the town centre (Oxford Road) is now unclassified, whereas the other half (Aylesbury Road) is now part of the B4445.
Buckinghamshire County Council had plans to rebuild the A418 between Aylesbury and Linslade as an at-grade D2. From the Aylesbury ring road, the A418 would have followed an upgraded Stocklake out of the town to a roundabout, where a link to Woodlands Roundabout on the A41 would have been built, and from there the new road would have taken the A418 northwards to meet the current road just north of Bierton. A short online section would have been upgraded, before a newly-built Rowsham bypass would have headed towards Wingrave Cross Roads, from which a northern bypass of Wing would have taken traffic to meet the Linslade western bypass just north of that village.
Although the A418 now ends at Linslade, historically it was much longer. Its original itinerary headed through Linslade and Leighton Buzzard, heading northwards for a while, before meeting the A5 north of Heath and Reach. From there it went through Woburn and Ridgmont to Ampthill, before turning north and heading to Bedford on the A6. Strangely, the A418 did not get a junction with the M1, that honour going to the B557 about a mile to the north-west. This meant that the B-road became significantly more important, to the extent that it was upgraded to become the A421, while the A418 declined in significance and was eventually downgraded. To the north of Leighton Buzzard, the original alignment of the A418 is now unclassified as far as Woburn, having once comprised the B5704, the former A4012, the former B559, and part of the A507 to Ampthill. Most of the original route from Ampthill to Bedford is now numbered B530, with the final stretch into the town centre being the A5141.
Road signs along the A418 are inconsistent over whether the road is of primary or non-primary status.
A study in 1987 highlighted that the road was signed as primary in Oxfordshire, but not in Buckinghamshire, but added that Buckinghamshire were going to be reviewing its status. The same study advised that the A418 had been included in a number of White Papers as a route that would be improved, despite it not being trunk. In 1987 the generic improvement was withdrawn in favour of a number of specific improvements to be delivered by local authorities: the Stone Bypass, the Aylesbury Bypass and the Leighton Buzzard Bypass. Buckinghamshire has now obtained green signs along this section o/s have it in green, and Google Earth now shows the A418 as a primary route.