A414 Park Street closure: every weekend from 11 September

The A414 between the M1 at Hemel Hempstead and Park Street Roundabout is to close for whole weekends from Friday 11 September 2026, and National Highways expects the arrangement to run until August 2027.

The order allows the trunk road to be shut from 8pm on Friday until 6am on Monday, and overnight from 8pm to 6am on other nights. A 40mph speed limit applies 24 hours a day on the approaches to Park Street Roundabout for the whole period, whether or not anyone is working.

National Highways advertised its intention to make the order in the Herts Advertiser on 27 August 2026. The notice says it is needed “to enable infrastructure works to Park Street Roundabout and a section of the A414 to be carried out in safety”. It replaces an earlier 2026 order covering the same stretch.

What the order allows

The two closures are defined by where the A414 meets the M1 at junction 8:

• eastbound, from the point the A414 diverges from the entry slip to the M1 southbound, through to Park Street Roundabout
• westbound, from Park Street Roundabout to the point the A414 merges with the exit slip from the M1 northbound

On top of the closures, the order imposes:

• a 40mph limit, 24 hours a day, eastbound from 1,400 metres west of Park Street Roundabout up to the roundabout, and westbound for 500 metres from its western side
• a 2.4 metre vehicle width restriction, at times, in the offside lane over broadly the same lengths

Emergency service vehicles are exempt from the speed limit. Emergency, traffic officer, works and winter maintenance vehicles are exempt from the closures. The order comes into force on 11 September and can run until the works are finished or for a maximum of 18 months, whichever comes first.

The diversion goes through the middle of St Albans

This is the part that will be felt furthest from Park Street. The published eastbound diversion does not stay on trunk roads. It leaves the M1 at junction 8 and runs:

• A414 Breakspear Way
• A4147 Leverstock Green Way
• Hemel Hempstead Road
• Bluehouse Hill
• A5183 Verulam Road
• High Street
• A1081 London Road, to London Colney Roundabout

That is Verulam Road and St Albans High Street, from Friday evening to Monday morning, for as long as the works last.

Westbound drivers are given two options. The first is that route in reverse, again through the city. The second avoids St Albans altogether by going the long way round through Watford:

• A405 North Orbital Road
• A41 North Western Avenue, from Leavesden Green
• A41 Watford Road
• A414 Two Waters Way, St Albans Road and Breakspear Way

What is being built has not been published

The notice does not say what the works are, beyond “infrastructure works to Park Street Roundabout and a section of the A414”. National Highways has published no scheme page for it, unlike the separate M1 resurfacing a few miles north.

Two things in the paperwork point at a developer rather than routine maintenance. General enquiries are directed not to National Highways but to a manager at Galldris Services, a civil engineering contractor based at Innova Park in Enfield. And National Highways’ own 7-day closure report has for weeks described the current A414 night closures as “S278/bypass works on behalf of Galldris Group”. A section 278 agreement, under the Highways Act 1980, is how a developer pays for and carries out changes to the public highway.

The largest development in that part of the district is the Strategic Rail Freight Interchange on the former Radlett aerodrome at Park Street, whose 2014 permission requires a Park Street and Frogmore relief road. Nothing published by National Highways or the council links the two, and we are not asserting the link. We have asked what is being built and will update this piece when we get an answer.

What it means for you

If you drive between St Albans and Hemel Hempstead at weekends, the direct route is gone from 11 September. Plan for the Watford loop or accept the run through the city centre. The order is drawn widely enough that the road can be shut every weekend until August 2027, though closures only take effect when signs say so.

If you live on or near Verulam Road, the High Street or London Road, expect traffic that does not normally use them, at times when those roads are usually quiet.

If you drive a wide vehicle, note the 2.4 metre restriction in the offside lane. Most cars and vans are comfortably inside that; plant, trailers and some agricultural vehicles are not.

The 40mph limit is permanent for the duration, not just during works. It applies 24 hours a day, including when the carriageway is fully open and empty.

Two other things are happening on the same roads next week. The M1 northbound between junctions 6 and 8 closes from 10pm to 5am on the nights of Monday 7 to Thursday 10 September, part of a separate £4 million resurfacing scheme. Hertfordshire County Council has also made orders closing Marford Road in Wheathampstead and Barley Mow Lane in St Albans from 7 September, for 19 days each. Both are covered on our St Albans roadworks and travel page, which we update each week.

Sources

• National Highways notice of an intended order, The A414 Trunk Road (M1 Junction 8, Hemel Hempstead to Park Street Roundabout, St Albans, Hertfordshire) (Temporary Restriction and Prohibition of Traffic) Order, published in the Herts Advertiser on 27 August 2026 and carried on the Public Notice Portal. Source for the closure hours, the 40mph limit, the width restriction, both diversion routes, the 11 September start, the expected end in August 2027, the 18-month maximum, the exemptions and the enquiries contact.
• National Highways 7-day road closure report, the spreadsheet published 4 September 2026 covering 4 to 10 September, for the description of the current A414 closures as S278 and bypass works on behalf of Galldris Group, and for the M1 junction 6 to junction 8 night closures.
• National Highways: M1 junction 6a to junction 8 maintenance for the £4 million cost of the separate M1 scheme.
• Hertfordshire County Council temporary traffic regulation notice, 3 September 2026 for the Marford Road and Barley Mow Lane orders.