M1 motorway

Looking north from B579 bridge at Chalton. Former cement works at Sundon to the right (May 1958)

The first section of the motorway, between Junction 5 (Watford) and Junction 18 (Crick/Rugby), opened on 1 November 1959, together with the motorway's two spurs, the M10 (from Junction 7 to south of St Albans originally connecting to the A1) and the M45 (from Junction 17 to the A45 and Coventry). Parts of the Hertfordshire section were built using steam rollers.[6]

The M1 was officially inaugurated from Slip End (close to Luton), celebrated by a large concrete slab[7] on the bridge next to the village, with inscription "London-Yorkshire Motorway – This slab was sealed by the Rt Hon Harold Watkinson M.P. – Minister of Transport – Inauguration Day – 24th March 1958". It was relocated, during widening works in 2007–08, to the eastern side of junction 10.

Looking north from a similar position south of Toddington services (July 1959)

This section of the M1 broadly follows the route of the A5 north-west. It started at the Watford Bypass (A41), which runs south-east to meet the A1 at Apex corner, and ended on the A5 at Crick. The M10 spur motorway connected the M1 to the North Orbital Road (A405/A414, a precursor of the M25) where it also met the A5 (now renumbered here as the A5183) and, 2 miles (3.2 km) to the east via the A414, the A6, which subsequently became part of the M25.

Although the whole of the first section opened in 1959, it was built in two parts, with the northern part (Junctions 10 to 18) being built by John Laing[2] and the southern part (the St Albans Bypass) being built by Tarmac Construction.[8]

The continuation of the motorway from Junction 18 towards Yorkshire was carried out as a series of extensions between 1965 and 1968. Diverging from the A5, the motorway takes a more northerly route through the East Midlands, via Leicester, Loughborough, Nottingham to Sheffield, where the M18 splits from the M1 at Junction 32 to head to Doncaster.

Originally, the M1 was planned to end at Doncaster but it was decided to make what was going to be the "Leeds and Sheffield Spur" into the primary route, with the 11-mile (18 km) section to the A1(M) south of Doncaster given the separate motorway number M18.

From Junction 32, the motorway passes Sheffield, Rotherham, Barnsley and Wakefield, reaching the original end of the motorway at (the original) Junction 44 to the east of Leeds. There were plans to route the M1 from just south of Junction 42, where it interchanges with the M62, round the west of Leeds to the A1 at Dishforth. The chosen route passes to the east of Leeds. With the M62 and M621, the M1 forms a ring of motorways around the south of Leeds.

The M1 and M621 interchange on the northbound carriageways at Leeds

In 1972, an extension of the M1 was opened into central Leeds as the Leeds South Eastern Motorway, where it met the Leeds South Western Motorway (M621) coming north-east from the M62 at Junction 3.

In July 1972, the then UK Minister for Transport Industries, John Peyton, announced that 86 miles (138 km) of UK motorway particularly prone to fog would benefit from lighting in a project that "should be" completed by 1973.[9] Sections to be illuminated included the M1 between Junctions 3 and 14, and between Junctions 16 and 24.[9] In August 2011, the Highways Agency announced that, despite being converted to Smart Motorway status, the lights will be switched off on stretches of the motorway between Junctions 10 (Luton) and 15 (Northampton) without affecting road user safety. The motorway junctions and their approaches, and a section of the M1 on either side of Junction 11 (north Luton), would have lighting columns replaced and remain lit. All lighting columns from Junctions 10 to 14 were removed completely, apart from some on slip roads.[10]

An increasing official interest in secondary safety was evident in an announcement in March 1973 that work would begin shortly on erecting "tensioned safety barriers" along the central reservation of a 34-mile (55 km) section of the M1 between Kegworth (J24) and Barlborough (J30).[11]

Between 1996 and 1999, the M1 section north of the M62 underwent a major reconstruction and extension to take the M1 on a new route to the A1(M) at Aberford. The new road involved the construction of a series of new junctions, bridges and viaducts to the east of Leeds. When the new section of M1 was completed and opened on 4 February 1999,[12] the Leeds South Eastern Motorway section of the M1 was re-designated as the M621, and the junctions were given new numbers: M621 Junctions 4 to 7.

Map showing construction dates of sections of the M1

M1 at Junction 4. The old overhead lane control gantries are still visible, which were replaced with newer, verge-mounted MS4 variable message signs in 2008.

The M1 was extended south towards London from its original starting point at Junction 5, in three stages. The first stage, opened in 1966, took the motorway south-east, parallel to the A41, to meet the A5 at junction 4 south of Elstree. The second phase continued east to Scratchwood (London Gateway Services occupies the location of the missing junction 3 from where an unbuilt spur would have connected to the A1 at Stirling Corner to the north-east). The M1 then runs south alongside the Midland Main Line towards Hendon, where it meets the A1 again at Junction 2 via a tightly curved flyover section. These flyovers connecting from the A1 were originally both for northbound traffic: the left one as the on-ramp to the M1, the right one going over the A1/A41 junction beneath to rejoin the A1 northbound.

Junction 2 is about 2.5 miles (4 km) south of the original Junction 3. Before the completion of Junction 2, southbound traffic left the motorway via a slip road which passed around the back of the now disused Homebase and under the A41/A1 Mill Hill Bypass, and looped round to join it at Fiveways Interchange. This slip road is still visible to southbound traffic approximately 650 yards (590 m) before Junction 2, and was maintained until the early 2000s, even though not accessible to traffic. The northbound slip road from the A1 is now partially used as the entrance way to a retail park and was once carried by bridge, but no longer reaches the northbound carriageway, because it is cut off by the motorway continuing south.

The final section of the M1 was opened to Junction 1 at Staples Corner in 1977. There the motorway meets the North Circular Road (A406) at a grade separated junction and roundabout. Unrealised plans from the 1960s would have seen the motorway continue through the junction on an elevated roadway to end at West Hampstead, where it would have met the North Cross Route, the northern section of the London Motorway Box, a proposed ring of urban motorway around the central area. The layout of the Staples Corner junction was originally built in accordance with those plans, although most of the London Ringways Plan had been cancelled by 1973. Around the same time, the section between the then-M10 and Junction 5 was widened from the original two lanes to three.

On its completion, the M1 acted as a fast link road between London and Birmingham via the M6. It also provided a link to London Luton Airport for those regions, and its proximity to the site of the Milton Keynes new town (designated in 1967) meant that it was soon providing a vital transport link to another major area.

In 2006, plans were published for the widening of 91 miles (146 km) from Leicester through to Leeds (Junctions 21–42) to four lanes each way.

Escalating costs across the whole of the Highways Agency programme, including the M1 project, on which costs had risen to £5.1 billion, as well as increasing opposition to major road expansion,[13][14] as well as criticisms by the Transport Select Committee and the National Audit Office, led to wide-ranging re-assessments of the Agency's project costs.[15] Widening was scaled back to the Junctions 6A to 10 scheme that was already in progress, and from Nottingham and Mansfield (Junctions 25–28), and hard shoulder running was to be used for other sections.

Many later developments, including Smart Motorway schemes, have been made to the M1, and these are detailed below.

A5-M1 Link (Dunstable Northern Bypass)

The route of the Dunstable Northern Bypass proposal and route options for the connecting Luton Northern Bypass.
Location	Central Bedfordshire
Proposer	Highways Agency
Status	Completed (summer 2017)
Type	Road
Cost estimate	£171 million to £217 million
Geometry	KML

The A5-M1 Link (Dunstable Northern Bypass) is a two-lane dual carriageway running east from the A5 north of Dunstable joining the M1 at a new Junction 11a south of Chalton.[16] Here, it is intended to join with a proposed Luton Northern Bypass to form a northern bypass for the wider conurbation. The A5-M1 Link aims to alleviate traffic congestion in Houghton Regis and Dunstable, reduce journey times for long-distance traffic travelling through Dunstable and improve the regional economy. The Highways Agency detrunked the A5 through Dunstable when the A5-M1 Link opened to the public in May 2017.[17] As part of the Dunstable Town Centre Masterplan, Central Bedfordshire Council built the 2.9 km Woodside Link to connect the new junction 11a to the industrial areas of Dunstable and Houghton Regis. Most of the road opened to traffic in autumn 2016 with the remaining section connecting to junction 11a.[18]

There is a proposal to widen the M1 to dual 4-lane or dual 5-lane between Junctions 21 and 21a and construct a new link road between the M1 and the M69. During this work the Leicester Forest East services would be closed, and possibly relocated.[19] Consultation took place in 2007.[20][21] As of April 2020, work on this scheme has still not begun.[22]

Following the report of a public inquiry in March 2013, the Secretary of State for Transport announced on 18 July 2013 that work to update the Catthorpe Interchange at junction 19, between the M1 motorway, M6 motorway and A14 road close to Catthorpe[23] would go ahead.[24] Work on the £191 million three-layer interchange started in January 2014[25] and the scheme was fully opened to traffic in December 2016.[26]

Work began on the 10-mile (16 km) section between the M25 and Luton (Junctions 6A and 10) in 2006 and opened in 2009, which included the construction of new parallel collector-distributor lanes between Junctions 7 and 8.

The M10 spur was built as a motorway because it inevitably led to the M1, but as non-motorway traffic could now travel between the A414 at Hemel Hempstead and Park Street Roundabout without having to access the M1, the M10 was downgraded to an A road, and designated as part of the A414 to allow for this. The widening or replacement of eleven underbridges on one or both carriageways, and replacing seven overbridges[27] at a cost of £294 million.[28] A variable mandatory speed limit system was installed, making this the first Smart Motorway scheme on the M1.

Work to introduce dynamic hard shoulder running on approximately 15 miles (24 km) of motorway between Luton and Milton Keynes (J10-13) was completed in December 2012, at a total cost of £327 million.[29] This made the hard shoulder available to be opened as a traffic lane where additional capacity was necessary. Modifications were made to Junctions 11 and 12,[30] to allow for four lanes running through each junction, and the A421 road from Junction 13 to the Bedford southern bypass was also upgraded to two lanes each way during this period.[31] The scheme will likely be converted to all lane running at some point in the 2020 decade, alongside all other dynamic hard shoulder running schemes. This was because a Government review into smart motorways found dynamic hard shoulder running was too confusing for drivers, leading to plans to convert all dynamic hard shoulders into permanent running lanes.[32]

Work to widen the 15-mile (24 km) section from Nottingham to Mansfield (J25-J28) to four lanes each way began in January 2008 and was completed in 2010, at a cost of £340 million.[33][34] A 50 mph limit, enforced by average speed cameras, was imposed for the period of construction, but it proved to be so effective that a permanent variable mandatory speed limit system was installed.[35]

Plans to dual the A421 from Junction 13 to Milton Keynes and to add capacity from Junction 10a on the Luton spur are being developed.[36][37] There are plans to reduce speed between M1 junctions 33 to 34, by Rotherham to 60mph, to reduce levels of nitrogen dioxide. The plans are to be implemented before October 2020 and the trial period is expected to last from 12 to 15 months.[38][39]