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Location Map ( geo)
Cameraicon.png View gallery (14)
From:  Hemel Hempstead (TL047060)
To:  Milton Keynes (SP890403)
Distance:  16.7 miles (26.9 km)
Meets:  A4251, A414, A4147, A505, A4012, A418, A5, A421, A509, A5130
Former Number(s):  A414, B486, B488, A505
Old route now:  B440, B4034
Primary Destinations
Highway Authorities

Buckinghamshire  • Central Bedfordshire  • Hertfordshire  • Milton Keynes

Traditional Counties

Bedfordshire • Buckinghamshire • Hertfordshire

Route outline (key)
A4146 Link in Hemel Hempstead
A4146 Hemel Hempstead – Leighton Buzzard
A4146 Leighton Buzzard bypass – Little Brickhill
(A5) Little Brickhill – Caldecotte
A4146 Caldecotte – Northfield Roundabout
Stoke Hammond bypass

The A4146 is a cross-country A-road in the Home Counties.

The route starts at a roundabout on the A4251 (former A41) on the western edge of Hemel Hempstead. Heading east, it starts off surprisingly rural in character as it crosses the River Bulbourne and the Grand Union Canal. Buildings do then appear but there is still a grassed area on the right of the road as far as the next roundabout (Hemel's magic roundabout) on the A414 on the southern edge of the town centre.

The two roads cannon off each other and the A4146 continues northwards along a relief road. We lose the B487 at the first roundabout and the A4147 at the second. At one time, the road continued straight ahead, however in 2017 with the opening of the Dunstable bypass, this was downgraded to B class, becoming the B440.

The road restarts on the Leighton Buzzard southern bypass as a continuation of the A505 at a roundabout junction with the B440. From here on, the A4146 is primary.

We follow a modern alignment past a few roundabouts and go over the West Coast Main Line. At one roundabout we meet the A418 and then turn northwards and continue as D2 (this part of the bypass is about 15 years newer than the previous section). There are still a few roundabouts, however. We run parallel to the WCML as we bypass Stoke Hammond and reach a roundabout on the southern edge of Milton Keynes, where we turn right, back over the railway. The road narrows at the next roundabout and we continue across the fields to reach the A5, at one of the few at-grade roundabouts on this section of that road. Northbound traffic for Bedford is signposted straight ahead at this roundabout on the unclassified road to Bow Brickhill station that then becomes V10, only to rejoin A4146 at the third roundabout. Southbound traffic (from M1 J14 towards Aylesbury) is signposted along A4146 to the A5 multiplex section.

There's a multiplex north along the A5 to the next junction, a dumbbell GSJ, where we join the H10. Now dual once more, we cross a bridge over a lake and continue past an industrial estate (the home of Red Bull Racing). We start to pass housing and then turn northwards at the next roundabout onto the V11. We continue on, alternately passing industry and housing to a roundabout where we turn right onto the H6. The road ends at the next roundabout on the A509, with that road continuing ahead to meet the M1.


In 1922 the route from Hemel Hempstead to Leighton Buzzard was the B486, with the route from Linslade to Bletchley and north the B488. Part of the B486 – the section south of the then B487 – was upgraded to A4146, with the A4147 being created at the same time in 1934/35. Together they formed a loop of A road serving Hemel, which remained like that – with the B486, A4146 and A4147 all ending at the same junction, until the 1970s, when the B486 was upgraded to A4146, taking the road to Leighton Buzzard.

Around 1980, the A4146 was extended further – to the A422 in Milton Keynes. It took the B488 from Linslade to Bletchley, then along Watling Street to meet the A421 at Roman Roundabout. From there it went north along V7 Saxon Street to H9 Groveway, then north on V8 Marlborough Street to the A422. This route is similar to that of the B4034, though the latter skips between V7 and V8 on H8 Standing Way, rather than H9, owing to the A421's shifting one road further north.

When the A41 Kings Langley bypass opened, there was a link road meeting the old A41 (A4251) at the A4146 junction. This new link became A414, and the A414 and A4146 south/east of the Plough Roundabout switched routes, creating a cannon.

Stoke Hammond Northern Link from Drayton Road to A5, at the Fenny Stratford Bypass southern roundabout, was opened on 9 February 2004. The section west of Stoke road was initially unclassified until phase 2 of the Stoke Hammond and Linslade Bypass was opened. Phase 2 was the Southern section from Drayton Road to A418 Wing Hill Roundabout (south-west of Linslade). The 5 mile dual carriageway was opened on 14 September 2007 by rally legend Paddy Hopkirk, who won the Monte Carlo Rally with British team-mate Henry Liddon in a Mini Cooper in 1964. Contractor was Alfred McAlpine.

The adjacent portion of The Leighton Buzzard and Linslade Southern Bypass had opened in November 1991 with the A505 number; the section between Wing Hill Roundabout and Billington Road Roundabout became the A4146 in 2007.

As stated above, in 2017 the section between Hemel Hempstead and Leighton Buzzard was downgraded to B class again, becoming the B440.

Named Junctions

Image Name Classified Road(s) Grid Reference More Info Map
THE Roundabout called " Magic" Hemel Hempstead - Geograph - 23621.jpg The Plough Roundabout A414 TL054063 Hemel's Magic Roundabout
SABRE • Google • geo
Hemel Hempstead- Gadebridge Park roundabout - Geograph - 187988.jpg Gadebridge Park Roundabout A4147 TL050085
SABRE • Google • geo
Photo-required.png Kelly's Kitchen Roundabout A5 • V4 SP893335
SABRE • Google • geo
Photo-required.png Caldecotte Roundabout A5 (southbound carriageway's slip roads) SP885351
SABRE • Google • geo
Photo-required.png Walton Park Roundabout V10 SP896356
SABRE • Google • geo
Photo-required.png Browns Wood Roundabout H10 • V11 SP903363 A4146 changes from the H10 to the V11
SABRE • Google • geo
Photo-required.png Walnut Tree Roundabout H9 SP899372
SABRE • Google • geo
Photo-required.png Brinklow Roundabout A421 / H8 SP898380
SABRE • Google • geo
Photo-required.png Monkston Roundabout H7 SP896387
SABRE • Google • geo
Photo-required.png Fox Milne Roundabout V11 • H6 SP887397 A4146 changes from the V11 to the H6
SABRE • Google • geo
Northfield roundabout near Junction 14 M1 motorway - Geograph - 2476121.jpg Northfield Roundabout A509 • A5130 • H5 SP890403 A4146 ends here
SABRE • Google • geo

Related Pictures
View gallery (14)
A4146 Stoke Hammond bypass - Coppermine - 15603.jpgHemel Hempstead- The Magic Roundabout - Geograph - 1668686.jpgIMG 0302.JPGTHE Roundabout called " Magic" Hemel Hempstead - Geograph - 23621.jpgNorthfield roundabout near Junction 14 M1 motorway - Geograph - 2476121.jpg
Other nearby roads
Hemel Hempstead
Leighton Buzzard
Milton Keynes
NCN51 • A5 • A50 • A421 • A422 • A506 (Hockliffe - Northampton) • A508 • A509 • A5130 • B488 • B526 • B557 • B4033 • B4034 • C5 (Milton Keynes) • C9 (Milton Keynes) • C13 (Milton Keynes) • C24 (Milton Keynes) • C41 (Milton Keynes) • C129 (Milton Keynes) • C130 (Milton Keynes) • C131 (Milton Keynes) • C132 (Milton Keynes) • C140 (Milton Keynes) • C141 (Milton Keynes) • C142 (Milton Keynes) • C143 (Milton Keynes) • C144 (Milton Keynes) • C145 (Milton Keynes) • C146 (Milton Keynes) • C147 (Milton Keynes) • C149 (Milton Keynes) • C150 (Milton Keynes) • C151 (Milton Keynes) • C152 (Milton Keynes) • C154 (Milton Keynes) • C155 (Milton Keynes) • C156 (Milton Keynes) • C157 (Milton Keynes) • C158 (Milton Keynes) • C159 (Milton Keynes) • C160 (Milton Keynes) • C162 (Milton Keynes) • C179 (Milton Keynes) • C181 (Milton Keynes) • E13 • E31 (via Carlisle) • E33 (London - Glasgow) • H1 (Milton Keynes) • H2 (Milton Keynes) • H3 (Milton Keynes) • H4 (Milton Keynes) • H5 (Milton Keynes) • H6 (Milton Keynes) • H7 (Milton Keynes) • H8 (Milton Keynes) • H9 (Milton Keynes) • H10 (Milton Keynes) • Holyhead Road • M1 • T11 (Britain) • V1 (Milton Keynes) • V2 (Milton Keynes) • V3 (Milton Keynes) • V4 (Milton Keynes) • V5 (Milton Keynes) • V6 (Milton Keynes) • V7 (Milton Keynes) • V8 (Milton Keynes) • V9 (Milton Keynes) • V10 (Milton Keynes) • V11 (Milton Keynes) • V12 (Milton Keynes) • Watling Street
A4100 • A4101 • A4102(W) • A4102(E) • A4103 • A4104 • A4105 • A4106 • A4107 • A4108 • A4109 • A4110 • A4111 • A4112 • A4113 • A4114 • A4115 • A4116 • A4117 • A4118 • A4119
A4120 • A4121 • A4122 • A4123 • A4124 • A4125 • A4126 • A4127 • A4128 • A4129 • A4130 • A4131 • A4132 • A4133 • A4134 • A4135 • A4136 • A4137 • A4138 • A4139
A4140 • A4141 • A4142 • A4143 • A4144 • A4145 • A4146 • A4147 • A4148 • A4149 • A4150 • A4151 • A4152 • A4153 • A4154 • A4155 • A4156 • A4157 • A4158 • A4159
A4160 • A4161 • A4162 • A4163 • A4164 • A4165 • A4166 • A4167 • A4168 • A4169 • A4170 • A4171 • A4172 • A4173 • A4174 • A4175 • A4176 • A4177 • A4178 • A4179
A4180 • A4181 • A4182 • A4183 • A4184 • A4185 • A4186 • A4187 • A4188 • A4189 • A4190 • A4191 • A4192 • A4193 • A4194 • A4195 • A4196 • A4197 • A4198 • A4199
Former iterations: A4105(W) • A4105(E) • A4108 • A4114 • A4115 • A4116 • A4125 • A4141 • A4150 • A4154 • A4160 • A4168

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