Road Cost per Kilometre
Tonnage and budget per kilometre of road by carriageway width and layer thickness, for the United Kingdom.
Quick answers
| Carriageway | Width | Area per km | 40 mm | 50 mm | 100 mm | 150 mm |
|---|---|---|---|---|---|---|
| Single lane | 3.65 m | 3,650 m² | 343 t | 429 t | 858 t | 1,287 t |
| Two lanes | 7.3 m | 7,300 m² | 686 t | 858 t | 1,716 t | 2,573 t |
| Two lanes + shoulders | 11.0 m | 11,000 m² | 1,034 t | 1,292 t | 2,585 t | 3,878 t |
| Four lanes | 14.6 m | 14,600 m² | 1,372 t | 1,716 t | 3,431 t | 5,146 t |
| Four lanes + shoulders | 21.0 m | 21,000 m² | 1,974 t | 2,468 t | 4,935 t | 7,402 t |
2026 prices
| Item | Low | Typical | High |
|---|---|---|---|
| AC surface course per tonne | £72 | £88 | £115 |
| HRA per tonne | £82 | £100 | £128 |
| SMA per tonne | £95 | £118 | £150 |
| Binder course per tonne | £62 | £76 | £98 |
| Base course per tonne | £56 | £70 | £90 |
| Recycled planings per tonne | £8 | £18 | £32 |
| Type 1 sub-base per tonne | £12 | £18 | £28 |
| Bitumen 40/60 per tonne | £490 | £525 | £560 |
| Driveway installed per m² | £45 | £65 | £90 |
| Car park installed per m² | £35 | £50 | £72 |
Recommended thickness
| Application | Surface course | Binder / base course | Unbound base |
|---|---|---|---|
| Footpath | 20–30 mm surface | — | 100 mm Type 1 |
| Domestic driveway, cars | 20–25 mm surface | 50–60 mm binder | 100–150 mm Type 1 |
| Driveway, vans or caravan | 25 mm surface | 60–70 mm binder | 150–200 mm Type 1 |
| Private car park | 30 mm surface | 60 mm binder | 200 mm Type 1 |
| Commercial car park | 40 mm surface | 60–80 mm binder | 225–300 mm Type 1 |
| HGV yard | 40 mm surface | 100–150 mm binder and base | 300–450 mm Type 1 |
| Estate road (adoptable) | 40 mm surface | 60 mm binder + 100 mm base | 225 mm Type 1 |
| Trunk road | 40–50 mm surface | 60 mm binder + 150–250 mm base | Capping as designed |
What moves the price
| Factor | Effect on price | Why |
|---|---|---|
| Distance from the plant | Very high | Hot mix must arrive above 130 °C, which limits a plant to roughly an hour's haul. Sites with two or three plants in range pay noticeably less than sites served by one. |
| Bitumen binder cost | High | Binder is 4.5–6% of the mix by weight but 25–35% of its cost, and it tracks crude oil with a lag of two to four months. |
| Season | Medium-high | Plants concentrate output into the paving season. Prices peak in mid-summer and soften at each end of the season. |
| Order size | Medium | Below about 5 tonnes a small-load surcharge usually applies. Above a few hundred tonnes the rate becomes negotiable. |
| Mix specification | Medium | Polymer-modified and stone mastic mixes cost 25–50% more per tonne than standard dense-graded material. |
| Aggregate supply | Medium | Regions that import aggregate carry that cost straight into the mix price. |
| Access and site constraints | Medium | Narrow access, weight-restricted bridges or overhead cables force smaller vehicles and raise the delivered rate. |
| Recycled content | Low-medium | Higher permitted recycled content lowers the plant's raw material cost. |
Ordering and delivery
What the plant needs from you
- Tonnage including your allowance, rounded up to the nearest half tonne.
- The mix designation — the plant's own name for it or the specification clause. "Tarmac" on its own is not an order.
- Delivery date and a time window the crew can actually meet. Hot mix cannot wait for a late start.
- Site access — gate width, turning radius, overhead cables, ground bearing capacity and any weight restriction on the approach.
- Discharge method — directly into the paver, into a transfer vehicle, or tipped for hand-laying.
- Whether tack coat and prime coat are included or supplied separately.
- The minimum order and small-load surcharge. Ask before you finalise the quantity — it may change how you sequence the work.
Delivery vehicles
| Vehicle | Typical payload | Best suited to |
|---|---|---|
| Rigid tipper (4-wheel) | 6–8 t | Very tight access, small domestic work |
| Rigid tipper (6-wheel) | 10–14 t | Domestic drives, restricted sites |
| Rigid tipper (8-wheel) | 16–20 t | The usual default for driveways and small car parks |
| Artic tipper | 26–29 t | Larger car parks and road work with good access |
| Insulated / thermal body | as above | Longer hauls, cold weather, thin surfacing |
| Material transfer vehicle | 25 t+ | Continuous paving, eliminates segregation |
A part-load at the end of a job is common. It is often worth increasing the design thickness slightly to fill the last vehicle rather than paying a small-load surcharge on two or three tonnes.
Waste and compaction allowance
Loose material behind the paver occupies roughly 20% more volume than the finished compacted surface. Add edge trimming, material left in the vehicle body and normal measurement tolerance, and you need an allowance on top of the calculated tonnage.
| Situation | Allowance | Reason |
|---|---|---|
| Simple rectangle, machine-laid, experienced crew | 5% | Minimal trimming and predictable compaction |
| Standard driveway or car park | 10% | Normal edge detail and some hand work at the perimeter |
| Curved edges or several separate zones | 15% | More offcuts and more hand placement |
| Hand-laid work and small patches | 15% | Hand compaction is less consistent |
| Recycled planings | 15–20% | Higher compaction factor and less predictable spread |
| Unbound granular base | 20–25% | Significant consolidation under the roller |
Round the final figure up to the nearest half tonne. Being short means a cold joint in the middle of the surface and a second delivery charge, which costs far more than the extra material would have.
Maintenance schedule
| Interval | Action | Why it matters |
|---|---|---|
| Within the first 48 hours | Keep all vehicles off | The mat is still cooling and takes a permanent impression easily. |
| First 30 days | Avoid turning the wheel while stationary; support trailer jacks on a board | The binder has not fully hardened and point loads leave marks. |
| Within 6–12 months | First surface dressing or seal, if specified | Slows oxidation of the binder. Applying it sooner traps volatiles and softens the surface. |
| Annually | Sweep, clear drainage, inspect edges and joints | Standing water at an edge is the most common cause of premature failure. |
| Every 1–2 years | Seal any cracks that have appeared | A sealed crack costs a fraction of the pothole it becomes. |
| Every 3–5 years | Reseal and, on car parks, re-line | Restores surface texture and appearance. |
| Every 10–15 years | Consider a surface course overlay | Resets the wearing layer while the structure below survives. |
| 20–25 years | Full reconstruction | Only when the structure itself has failed, not merely the surface. |
Deferred maintenance compounds quickly. A crack sealed early costs very little; the same crack left for two winters admits water, softens the base and becomes a full-depth patch. The economics of surfacing maintenance are almost entirely about intervening before water reaches the layers below.
The base underneath
The unbound layer under the surfacing does more structural work than the surfacing itself, and it is where most premature failures actually originate. A thinner bound layer over a deep, well-compacted, free-draining base will outlast a thicker bound layer over a shallow one.
| Subgrade | Approximate CBR | Base under domestic access | Base under commercial |
|---|---|---|---|
| Well-graded gravel | 20–40 | 100 mm | 150 mm |
| Sand, well drained | 10–20 | 100–150 mm | 150–200 mm |
| Silty sand | 6–10 | 150 mm | 200 mm |
| Loam | 5–8 | 150–200 mm | 200–250 mm |
| Silty clay | 3–5 | 200–250 mm | 250–300 mm |
| Heavy clay, poorly drained | 2–3 | 250–300 mm plus geotextile | 300–450 mm plus stabilisation |
| Peat or organic soil | under 2 | Excavate and replace | Excavate and replace |
Two additions repay their cost on marginal ground: a separation geotextile between the subgrade and the granular layer, which stops stone punching down into soft clay and can save 50–100 mm of aggregate; and proof-rolling with a loaded vehicle before any stone is placed, which finds the soft spots while they are still cheap to deal with.
Remember that the granular base is usually the larger tonnage of the two. A 100 m² area with 200 mm of base at 2,100 kg/m³ needs 42 tonnes of stone against roughly 12 tonnes of surfacing at 50 mm. Budget and order for both.
Calculator
Frequently asked questions
How many tonnes do I need?
Area in m² × compacted thickness in m × 2.35. A 100 m² area at 50 mm needs about 11.8 tonnes.
How many m² does a tonne cover?
About 8.5 m² at 50 mm compacted.
What allowance should I add?
10% for standard work, 5% for simple machine-laid rectangles, 15% for curved or hand-laid areas.
Does the calculator handle several areas?
Yes — add a zone per shape, each with its own thickness and mix type. Multi-layer structures and irregular sites are entered directly.
Which standards apply?
BS EN 13108 and BS 594987, administered by National Highways and the Specification for Highway Works.
Sources and further reading
- Mineral Products Association — Asphalt
- National Highways (UK)
- BSI — BS 594987
- EAPA — European Asphalt Pavement Association
2026 Q3