Abnormal load routing for a large delivery

A delivery becomes an abnormal load when the vehicle and its load exceed the normal construction and use limits, and the thresholds that matter in practice are a gross weight above 44,000 kg, a width over 2.9 metres, or a rigid length over 18.65 metres. Cross any of those and the movement runs under the special types order, with notification duties to the police, to highway authorities and to bridge owners depending on how heavy and how wide the load is. Abnormal load route planning is the item most often missing from a rural planning application that involves one large component.

Councils rarely refuse a scheme over this. They do impose conditions that stop work until a route has been agreed, which on a farm diversification project with a fixed installation date is the same thing.

When a delivery becomes an abnormal load

The classification drives everything else. Loads carried under the special types order are grouped by weight into categories, and the heavier the category, the longer the notification period and the more parties have to be told.

Typical rural examples are a steel portal frame bay for a grain store, a slurry or digester tank, a bulk feed bin, a crane needed to erect any of them, a wind turbine component, a large transformer for a grid connection, and occasionally a modular building unit delivered in one piece.

Width catches people more often than weight. A tank at 3.4 metres wide weighs little, and it still cannot pass a parked car on a single track lane with hedges on both sides, and the notification and escort obligations follow from the width alone.

Notification duties and who to tell

Notifications are made through the national electronic service for abnormal loads, which distributes them to the police forces, highway authorities and structure owners on the route. The haulier normally does this, and the developer's job is to make sure it happens early enough and to supply the route.

• Police forces for each area the load passes through, with the notice period set by the category of the load.
• Highway authorities for the roads used, including the local authority for unclassified lanes and National Highways for the strategic network.
• Owners of structures on the route, which includes bridge owners, Network Rail where a railway bridge is crossed, and the navigation authority where a canal or river structure is involved.
• The relevant utility where overhead lines or a low bridge require attendance.

Where the load exceeds the limits the order permits at all, a special order from the Secretary of State is needed instead, which takes considerably longer and should be identified at feasibility rather than at delivery.

Keep the notifications. A condition requiring an agreed route is discharged by producing the correspondence rather than by describing it.

Route survey and pinch points

A route survey is a physical exercise, driven and walked, with photographs and measurements at every constraint. Desk work alone misses the things that stop a load.

1. Carriageway and effective width at each pinch point, measured rather than taken from mapping, with verge condition and overhanging vegetation accounted for.
2. Swept path analysis at every junction the vehicle must turn through, using the actual vehicle and trailer configuration with the load in place.
3. Overhead clearances: bridges, overhead power and telecoms lines, traffic signals, gantries and tree canopies.
4. Street furniture that would have to be removed or protected, with its owner identified.
5. Gradients and crossfall, which matter for a high or long load more than for a heavy one.
6. Turning and waiting areas where the load must be held for an escort or for a traffic management window.
7. The final site access and the manoeuvre within the site, which is where loads most often have to be craned off at the gate.

Structures, weight limits and assessments

Where a structure on the route cannot be shown to carry the load, the owner can require an assessment at the applicant's cost, and that assessment takes time. Bridge assessment is specialist structural work, and the answer is sometimes that the crossing is not possible at any weight.

Three practical responses: change the route, change the vehicle so the axle loads fall within the structure's capacity, or split the load. Splitting is available only where the load is divisible, and an abnormal indivisible load by definition is not.

A level crossing is a separate problem. Long, low or slow vehicles need the railway operator's agreement to cross, and that permission is given at specific times with its own conditions.

Temporary works to verges and hedges

Rural routes usually need physical work, and each item needs a permission.

Verge protection with track panels or geotextile and stone requires the highway authority's agreement, and reinstatement to its satisfaction. Cutting back hedges and overhanging branches on the highway side falls under the highway authority's powers, and work to a hedge is constrained by the bird nesting season as well as by any hedgerow protection, so timing is not free.

Temporary removal of a sign, bollard or lighting column needs the owner's permission and a reinstatement commitment. And any works in the highway need traffic management designed to the national standard, which on a single track lane usually means a convoy arrangement with stop and go boards rather than signals.

Where off-site highway alterations become permanent, a section 278 agreement follows the permission and runs on its own timetable.

Timing and escort requirements

Heavier and wider loads carry escort requirements, which for the largest movements means a police escort arranged through the notification process and for others a private escort vehicle. Police availability is finite and in rural areas the window may be a specific night of the week.

Movements are commonly restricted to off-peak or night-time hours, which then interacts with any noise condition on the permission. A delivery condition limiting construction hours to daytime and an abnormal load that can only move at 2am is a conflict to resolve at application stage rather than after.

Build the lead time into the programme honestly. Notification periods, structure assessments, escort availability and traffic management approval are sequential rather than parallel, and the total is frequently measured in months.

Evidence for the planning application

A rural application involving an abnormal load should include a route plan from the strategic network to the site with the pinch points numbered and photographed, swept path drawings at each constrained junction, a list of structures on the route with their restrictions, the number and timing of abnormal movements distinguished from ordinary construction traffic, the temporary works proposed with the owner of each asset identified, and the traffic management principle.

Put it in a Construction Traffic Management Plan rather than scattering it through a transport document, and keep the abnormal movements in a separate section so the highway officer can find them. Where the ordinary construction traffic case also needs setting out, a Transport Statement covers it.

And if the route touches the strategic road network, expect a formal response. The pattern of objections is covered in our note on when National Highways objects.

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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.