Swept path analysis, pavement thickness, kerb radii, gradients, and compliance for truck access
A comprehensive 2026 guide to heavy vehicle driveway design — covering design vehicle selection, swept path analysis, entry and exit gradients, pavement thickness, kerb radii, sight distance, loading dock geometry, and relevant Australian Standards and Austroads references for engineers, traffic consultants, and planners.
A poorly designed heavy vehicle driveway creates operational problems, safety hazards, structural pavement failures, and costly remediation. Getting the geometry and construction right from the start is essential in 2026.
Heavy vehicle driveway design encompasses the geometric, structural, and operational planning required to provide safe and efficient access for trucks, semi-trailers, articulated vehicles, buses, and other heavy vehicles to and from a site. It covers entry and exit geometry, swept path clearances, driveway gradients, kerb radii, pavement thickness, sight distances, and loading dock layout. Poor design leads to vehicles overriding kerbs, mounting footpaths, damaging property, blocking public roads during manoeuvres, and causing premature pavement failure under repeated heavy axle loads.
A formal heavy vehicle driveway design or swept path assessment is required for most development applications (DAs) involving industrial, commercial, logistics, retail, or mixed-use sites that generate significant heavy vehicle movements. In Australia, this is typically triggered by local government development control plans (DCPs), state road authority access policies, and traffic impact assessment (TIA) guidelines. Any site expecting regular access by vehicles over 4.5 tonnes GVM should be assessed against heavy vehicle driveway design standards, including those from Austroads and state road authorities.
Effective heavy vehicle driveway design rests on four principles: appropriate design vehicle selection (match the vehicle template to the largest vehicle that will regularly use the site); geometric adequacy (ensure swept path clearances, gradients, and radii accommodate that vehicle); structural sufficiency (design the pavement to carry the expected axle loads over its design life); and safe integration with the public road, footpath, and pedestrian network. See our guide on backfilling around concrete foundations for related pavement subgrade preparation guidance.
The starting point for any heavy vehicle driveway design is selecting the correct design vehicle — the largest and most demanding vehicle expected to regularly use the driveway. Austroads and the National Heavy Vehicle Regulator (NHVR) define standard vehicle dimensions and turning templates used across Australia. Over-designing for a vehicle that never visits wastes money; under-designing for the actual operating vehicle creates dangerous and unworkable access.
Design vehicle templates are used in swept path analysis software such as AutoTURN, SIDRA, Transoft Solutions, and TURN to verify that a vehicle can navigate the driveway entry, internal circulation, and exit without encroaching on footpaths, median islands, opposing traffic, or adjacent structures. The design vehicle must be able to complete all required manoeuvres from the worst-case starting position on the public road, using no more than the legal lane width available.
Design vehicle selection must reflect the largest vehicle that will regularly use the site. Dimensions are overall vehicle envelopes per Austroads Guide to Road Design Part 3 and NHVR PBS standards 2026. Always verify current vehicle dimensions against the applicable state heavy vehicle network permit conditions.
The design vehicle used in swept path analysis is not always the same as the largest vehicle permitted on the adjacent public road. A site may be designed for a semi-trailer (19 m) even if B-doubles (25 m) are legally permitted on the road, because the site operator only expects semi-trailers. Conversely, if a logistics centre expects B-double deliveries, the driveway must be designed to accommodate them regardless of whether B-doubles are the dominant vehicle on the road. Always confirm the expected vehicle mix with the site operator and the relevant road authority before finalising the design vehicle selection.
The geometric design of a heavy vehicle driveway entry and exit determines whether vehicles can safely enter and exit the site without conflicting with pedestrians, cyclists, or other road users. The key geometric parameters are driveway width, kerb return radii, throat length, sight distance, and the angle of intersection with the public road. Each of these must be designed to suit the selected design vehicle and the traffic volume and speed on the adjacent road.
Heavy vehicle driveways typically require a minimum throat width of 6.0–9.0 m for two-way operation (one lane each direction), or 3.5–5.5 m for one-way operation. For articulated vehicles and B-doubles, wider throats of 7.0–10.0 m may be required depending on the angle of entry and the available manoeuvre space inside the site. Width must accommodate the vehicle body plus clearance to kerb and any gatehouse or bollard structures.
The kerb return radius at the driveway entry controls how tightly a vehicle can turn from the road into the site. Heavy vehicle driveways typically require kerb radii of 10–15 m for rigid trucks and 15–20 m for semi-trailers. B-doubles and road trains may require radii of 20–30 m or compound curves. Swept path analysis must confirm that the design vehicle's rear wheels track inside the kerb return without mounting the kerb or footpath.
Adequate sight distance must be provided in both directions along the public road from the driveway entry to allow a departing heavy vehicle driver to safely identify and merge with approaching traffic. Austroads sight distance requirements depend on the posted speed of the adjacent road — at 60 km/h, a minimum approaching sight distance of approximately 70–90 m is required. Sight triangles must be kept clear of vegetation, parked vehicles, signage, and structures both during design and in perpetuity during site operation.
The throat length is the distance from the property boundary (or edge of the public road) to the first internal intersection or parking area. For sites with high heavy vehicle volumes, a minimum throat length equal to the length of the design vehicle is recommended — typically 19 m for semi-trailers and 25 m for B-doubles. This prevents queuing vehicles from blocking the public road while waiting for internal clearance, which is a common cause of traffic and safety incidents at busy logistics sites.
Maximum driveway gradient for heavy vehicle access is typically 1:10 (10%) for short grades up to 30 m and 1:12.5 (8%) for longer grades. Loaded semi-trailers and B-doubles should not be expected to climb grades steeper than 8% on driveways. Critical change-of-grade points (sumps and crests) must be rounded with vertical curves to prevent high-centred vehicles — the minimum vertical curve length depends on the wheelbase of the design vehicle and should be verified by swept path analysis in the vertical plane.
Where site area permits, one-way circulation (separate entry and exit driveways) is strongly preferred for heavy vehicle sites as it eliminates head-on conflicts, reduces required driveway widths, and simplifies swept path geometry. Two-way operation requires vehicles to pass in the throat, requiring wider driveways and careful attention to forward and rearward visibility. One-way circulation also improves pedestrian safety by reducing the unpredictability of large vehicle movements near building entries and car parks.
Driveway gradient is one of the most critical parameters in heavy vehicle driveway design. Excessive gradients prevent loaded trucks from safely entering or exiting a site, cause grounding of long wheelbase vehicles at change-of-grade points, and create braking and runaway risks on exit. The following table summarises maximum and recommended gradients for different heavy vehicle driveway contexts.
| Driveway Context | Maximum Grade | Recommended Grade | Vertical Curve Required | Notes |
|---|---|---|---|---|
| General heavy vehicle driveway (short grade <30 m) | 10% (1:10) | ≤8% (1:12.5) | At all grade changes | ✅ Standard |
| General heavy vehicle driveway (long grade >30 m) | 8% (1:12.5) | ≤6% (1:16.7) | At all grade changes | ✅ Standard |
| B-double / road train access | 6% (1:16.7) | ≤4% (1:25) | Mandatory — long wheelbase | ⚠️ Check operator requirements |
| Loading dock ramp (below grade) | 15% (1:6.7) short ramp | ≤12% (1:8.3) | Mandatory at top and bottom | ⚠️ Sump vertical curve critical |
| Driveway within 6 m of road edge | 5% (1:20) | ≤3% (1:33) | At grade change from road | ✅ Minimises road/site conflict |
| Fuel tanker / hazmat vehicle access | 5% (1:20) | ≤3% (1:33) | Required | ❌ Steeper grades prohibited |
| Driveway at footpath crossing (pedestrian zone) | See footpath crossfall rules | Maintain ≤2% crossfall in footpath zone | N/A | ⚠️ AS 1428.1 applies to footpath |
One of the most frequently overlooked aspects of heavy vehicle driveway design is the need for vertical curves at all significant changes of grade. A rigid truck or semi-trailer with a long wheelbase and low ground clearance can become high-centred (grounded) at an abrupt change from a steep positive grade to a flat area, or at the base of a loading dock ramp. The minimum vertical curve length (K value) at each change of grade must be calculated based on the design vehicle's wheelbase and ground clearance. AutoTURN and similar software can simulate this in three dimensions. Failure to provide adequate vertical curves is a common cause of driveway rejection by road authorities and councils at the development assessment stage.
The structural pavement design for a heavy vehicle driveway must account for the axle loads, frequency of heavy vehicle movements, subgrade strength, and design life of the pavement. Heavy vehicle driveways are subjected to far greater structural demands than standard car park or residential driveway pavements, and standard driveway specifications are entirely inadequate for semi-trailer or B-double loading.
Austroads Pavement Design Guide (AGPT02) provides the primary design methodology for Australian heavy vehicle driveway and road pavement thickness design. For concrete rigid pavements, AS 3600 and the Concrete Institute of Australia (CIA) industrial pavement guides are also relevant.
The following indicative pavement thicknesses are based on Austroads flexible and rigid pavement design principles for typical heavy vehicle driveway applications. These are indicative values only — a full pavement design should be undertaken for all commercial and industrial driveway projects, based on actual subgrade testing (CBR) and confirmed traffic data.
| Design Vehicle / Application | Subgrade CBR | Concrete Slab Thickness | Asphalt + Base Thickness | Sub-base Required |
|---|---|---|---|---|
| Light rigid truck (<12.5 m, low frequency) | 5–10% | 150–175 mm | 50 mm AC + 200 mm base | 150 mm compacted |
| Heavy rigid truck (up to 12.5 m, medium freq.) | 5–10% | 175–200 mm | 60 mm AC + 250 mm base | 150–200 mm compacted |
| Semi-trailer (19 m, regular daily movements) | 5–10% | 200–250 mm | 75 mm AC + 300 mm base | 200–250 mm compacted |
| B-double (25 m, regular daily movements) | 5–10% | 250–300 mm | 90 mm AC + 350 mm base | 250–300 mm compacted |
| Semi-trailer on poor subgrade | <3% | 275–325 mm | 90 mm AC + 400 mm base | 300 mm+ with geotextile |
| Loading dock apron (slow speed, high freq.) | 5–10% | 250–300 mm (preferred) | Not recommended | 200–250 mm compacted |
Rigid concrete pavement is strongly preferred over flexible asphalt at loading dock aprons, slow-speed turning areas, and high-frequency heavy vehicle paths for three reasons: resistance to rutting and shoving under slow-speed, high-torque heavy vehicle movements; resistance to fuel and hydraulic oil contamination that softens asphalt; and lower long-term maintenance cost over a 30–40 year design life. Concrete pavement at loading docks should be reinforced (typically mesh or air-entrained concrete in freeze-thaw climates) and jointed to control cracking under thermal and load cycling.
The following process reflects current best practice for heavy vehicle driveway design in Australia in 2026, covering the full scope from initial briefing through to construction documentation and council submission.
The Austroads Guide to Road Design (AGRD) — particularly Parts 3, 4A, and 6A — provides the primary Australian engineering reference for driveway design, design vehicles, swept path geometry, sight distance, and pavement design for heavy vehicle access.
Visit Austroads →The NHVR publishes vehicle dimension and mass limits, PBS (Performance Based Standards) vehicle specifications, and network access conditions that define the design vehicle parameters used in heavy vehicle driveway design across Australia in 2026.
Visit NHVR →Browse the complete library of concrete and civil engineering guides on ConcreteMetric — covering pavement design, structural assessment, sustainability, and construction best practice for engineers and planners in 2026.
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