M1 Junction 7 to Junction 8 (St Albans / Hemel Hempstead)

One mile of motorway between Hemel Hempstead and St Albans, carrying almost 159,000 vehicles a day. It is one of the shortest gaps between junctions on the whole M1, one of the busiest, and it was the first stretch of the M1 anywhere to get variable speed limits.

Nearly 159,000 vehicles a day, over a single mile

That makes it the 2nd busiest of the 42 measured stretches of M1 mainline, and the 25th for the share of its traffic that is lorries. The average across the measured M1 is 119,883 vehicles a day — see how busy the M1 is junction by junction.

The local traffic has its own road here, alongside the motorway

Junction 7 is Beechtrees Interchange, for the A414 to St Albans and Hatfield. Junction 8 is Breakspears Interchange, for the A414 into Hemel Hempstead. It is the same A-road at both ends, and that is the point: a great deal of the traffic here is going from one Hertfordshire town to the next, not up or down the country.

When the motorway was widened in 2008, separate collector–distributor carriageways were built between these two junctions specifically to keep Hemel-to-St-Albans traffic off the main line. So the four lanes each way you are driving on are not the whole road — there is a parallel local carriageway beside you doing a different job.

A controlled motorway, not all-lane running — the hard shoulder is still there

This gets confused often, so it is worth being exact. National Highways classifies the M1 from junction 6a to junction 10 as a controlled motorway: variable mandatory speed limits on overhead gantries, but the hard shoulder retained and never used as a running lane. It is not all-lane running.

It opened to traffic on 19 December 2008 as part of a £294m widening of junctions 6a to 10, and it was the first smart motorway scheme on the M1. Those variable limits can drop from 70mph to as low as 20mph, and they are enforced — over 5,150 penalty notices were issued for exceeding them between junctions 6 and 8 in the three years to 2017.

Roughly one vehicle in nine here is a lorry, and the warehouses explain why

18,418 lorries a day use this mile. Immediately west of junction 8 is Maylands Business Park, which the local enterprise partnership puts at more than 650 businesses employing over 20,000 people, now being extended as the Hertfordshire Innovation Quarter. A Prologis industrial park sits on the corner of Green Lane and the A414 at the junction itself.

That is also why junction 8 keeps appearing in planning documents. Hertfordshire’s A414 corridor strategy notes that most traffic approaching the M1 at junction 8 originates in Hemel Hempstead, and National Highways has told the St Albans local plan examination that growth at Hemel Garden Communities would, without mitigation, queue traffic back onto the M1 northbound off-slip.

There are no services on this stretch, and the nearest hospital has no A&E

Neither junction has services. The nearest are London Gateway to the south, between junctions 2 and 4, and Toddington to the north, between junctions 11 and 12. Hemel Hempstead Hospital is close by but its accident and emergency department was removed in 2006, so it is not where casualties from this stretch would go.

Junction 7 used to be a motorway junction, and junction 8 is where Buncefield happened

The arm of the A414 running south-east from junction 7 is the former M10. It opened on 2 November 1959, the same day as the M1 itself, making it one of the oldest motorways in Britain — and it was downgraded to an A-road on 1 May 2009, less than a year short of its fiftieth birthday, because the very widening described above had made it redundant.

Beside junction 8 sits the Hertfordshire Oil Storage Terminal at Buncefield. It exploded at 06:01 on 11 December 2005, registering 2.4 on the Richter scale, and the M1 was closed between junctions 6a and 12 — some eighteen miles of motorway. Over 40 people were injured; nobody was killed.

Traffic figures on this page are Department for Transport road traffic statistics, annual average daily flow for 2025, both directions combined. Annual average daily flow counts how many vehicles use a stretch across the year. It does not measure how fast they travel, so the busiest stretch is not automatically the slowest.