Construction access for abnormal and oversized loads

Abnormal load construction access is not a planning matter, and that is exactly why it derails programmes. A tower crane base, a precast stair core, a transformer or a 30 metre steel truss moves under a separate statutory regime with its own notification periods, its own consenting bodies and its own veto points. Planning permission for the development says nothing about whether the load can physically reach the site.

The sequence that causes trouble is familiar. Permission granted, contractor appointed, delivery booked, and then a bridge assessment two weeks before the lift says no.

Which loads count as abnormal

A load becomes abnormal when the vehicle carrying it exceeds the limits set by the Construction and Use Regulations. In broad terms that means a gross weight above 44,000 kg, an axle load above the normal limits, a width over 2.9 metres, or a rigid length beyond about 18.65 metres. Vehicles carrying such loads run instead under the Road Vehicles (Authorisation of Special Types) (General) Order 2003, in one of its weight categories, and the heaviest or widest movements need a special order from the Secretary of State rather than falling under the general authorisation.

Check the current thresholds before you plan a movement, because the figures and the categories have been amended, and the consequences of getting the category wrong are a refused movement rather than a fine.

Two practical points follow. Indivisibility matters: the regime is for loads that cannot reasonably be broken down, so a load that could arrive in three pieces may not qualify. And the vehicle, not the item, is what is measured, so a modest precast unit on a long low loader can be an abnormal load while a heavier item on a suitable trailer is not.

Notification duties and lead times

Notification runs to three sorts of body: the police forces along the route, the highway authorities whose roads are used, and the owners of bridges and other structures on the route. National Highways operates an electronic notification service that distributes a movement notice to all of them from a single submission, and most hauliers use it as a matter of course.

Lead times are set by the category of movement. Lighter abnormal loads typically need a couple of clear days notice to the police. Heavier movements, and those crossing structures, require several clear days notice to highway and structure owners, and a special order application takes considerably longer than either.

The honest planning point is that the statutory minimum is not the working lead time. A bridge owner given the statutory notice may simply decline the crossing, and finding an alternative route then takes weeks. Treat the statutory period as the last possible date and work back from a first enquiry made months earlier.

Route survey and structural capacity

A route survey is a physical drive of the route in a vehicle with the dimensions of the proposed movement, recording constraints and measuring anything marginal. What it records:

• Overhead clearances: bridges, gantries, overhead lines, tree canopies and signage.
• Horizontal constraints: carriageway widths at pinch points, kerb radii, roundabout islands, build outs and pedestrian refuges.
• Vertical geometry: crests and troughs where a long trailer grounds, and gradients where a heavy load loses traction.
• Structures: every bridge, culvert, retaining wall and buried chamber on the route, with its reference.
• Street furniture: columns, signs, bollards, guardrail and cabinets within the swept path.

Structural capacity is assessed by the owner of each structure against the axle configuration you propose, not against gross weight alone. Spreading a load over more axles frequently turns a refusal into a consent. So does changing the trailer type, and the haulier is usually better placed than the designer to suggest which.

Where the route touches the strategic road network, the assessment sits with National Highways, and its position is decisive in practice. The note on when National Highways objects to an application covers how that body engages with development more generally.

Weight and width restrictions

Environmental weight limits, width restrictions and height barriers are the constraints most often discovered late, because they do not appear on a routing package built from a lorry satellite navigation dataset.

Environmental weight limits usually carry an exemption for access, which does not automatically authorise an abnormal load. Where a limit is absolute, the options are a temporary traffic regulation order suspending it, a signed diversion agreed with the authority, or a different route. Orders made under the Road Traffic Regulation Act 1984 take time and, where they require advertisement, that time is measured in weeks.

Low bridges and rail structures deserve separate attention. A rail bridge strike stops trains, the liability is substantial, and route approval for anything marginal will involve the infrastructure owner as well as the highway authority.

Moving street furniture and closing roads

Temporary removal of a lamp column, a sign, a bollard or a length of guardrail is arranged with the highway authority, at the applicant's cost, under the authority's own permit or licence arrangements. Statutory undertakers' apparatus is slower again, because the diversion is designed and carried out by the undertaker to its own programme.

Full or partial closures, one way suspensions and parking bay suspensions each have their own procedure and notice period. Where the movement is part of works the developer is carrying out in the highway anyway, it is often simpler to fold the requirement into the highway works agreement, and the note on section 278 agreements that follow a permission explains how that mechanism is used.

Budget for reinstatement and for a bond or indemnity. Authorities routinely require security against damage to the carriageway, the footway and any structure crossed.

Timing, escorts and the movement window

Most authorities push abnormal load movements into off peak or night windows, and the police may impose conditions on timing, speed and escort arrangements. Attendance is not automatic: self escorting arrangements cover many movements, with private escort vehicles and trained staff, while the widest and heaviest movements attract police involvement.

Night movements interact with the planning permission. A condition restricting construction hours to daytime working, drafted with noisy site operations in mind, can inadvertently prohibit the delivery window the police require. Ask for the condition to be worded so that pre-notified abnormal load deliveries outside the stated hours are permitted with the authority's prior written agreement.

Getting it into the construction documents

The place for all of this is the construction traffic documentation submitted for approval, usually a Construction Traffic Management Plan secured by condition, sometimes folded into a wider Construction Management Plan.

What to include, at the level of detail an officer can approve:

1. A schedule of anticipated abnormal load movements with dimensions, weights and indicative dates.
2. The approved route on a plan, with the structures crossed listed.
3. Swept path drawings at every constrained junction and site access.
4. The notification route and the consenting bodies, with responsibilities named by role rather than by person.
5. The timing window sought, with the reason.
6. The street furniture or apparatus to be moved and the arrangements for reinstatement.

Submitting that detail with the application, rather than after permission, is worth the effort on any scheme with a known heavy component. A highways officer who has already seen the swept paths is a far easier consultee at discharge of conditions than one meeting them for the first time under time pressure.

One honest caveat. Movement approvals are given close to the date and can be withdrawn where a structure is downgraded after an inspection, so a programme that depends on a single delivery date with no float is carrying a risk no amount of paperwork removes.

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This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.