Kerbs before asphalt: getting the sequence right

If the asphalt paver arrives while the kerb gang is still setting units in the same strip, the programme has caught up with itself. Those operations can happen on the same site, but they should not be competing for the same edge, the same levels or the same access route.

Kerbs normally go in before the asphalt they retain. That does not mean every kerb across a large estate must be finished before any paving starts. It means each work area needs a complete, protected edge and confirmed drainage levels before the paving train enters it. On a live warehouse yard or occupied estate, the traffic route through the works has to be planned with the construction sequence, not drawn around it afterwards.

What the kerb line controls

A kerb is not a decorative finish added once the road is built. It can define the pavement edge, hold the asphalt layers at the perimeter, establish upstands and crossings, and help direct surface water towards gullies or channels. If its line or level moves, the surfacing crew inherits the error.

The project specification and drawings remain the authority for the job. For motorway and all-purpose trunk-road work, the current Manual of Contract Documents for Highway Works provides the base specification, with the version applying to a scheme set by its contract. A private estate may use a different specification, but the practical principle is the same: the kerb needs the designed bedding, backing and geometry before it is asked to retain a compacted pavement edge.

That geometry links straight back to drainage. The top of kerb, channel line, gully frame and finished asphalt level are one system. Set any one of them independently and the surface can end up holding water, sending it across a pedestrian route or leaving an abrupt lip at a crossing.

The usual sequence

On a straightforward estate road or car park, the sequence normally works from the buried elements upwards:

Confirm the setting out and drainage strategy. Fix the finished levels, falls, tie-ins, channels, gullies and thresholds before physical work commits the design to the ground.
Complete buried drainage and service crossings. Install and test runs that would otherwise require the new pavement to be cut open. Protect known services and keep records of anything that will disappear below the construction.
Prepare the formation and pavement foundation. Excavate, improve or proof the formation as designed, then place and compact the capping and sub-base needed for the specified pavement.
Set the kerbs, channels and fixed ironwork. Build them to the design line and level with the specified bedding, foundation and backing. Protect the work for the required period rather than letting site traffic test it early.
Place asphalt base, binder and surface courses. Prepare the receiving layer, treat joints and interfaces as specified, then pave and compact without using the kerb as something for the roller or delivery vehicles to lean on.
Finish markings, signs and local details. Complete the items that depend on the final surface, then inspect drainage behaviour, transitions and access before reopening the area.

The contract pavement specification sets the requirements for preparing the receiving layer, placing the mixture, treating joints and achieving compaction. On private work, that may be a project-specific pavement design. Either way, the paving crew needs a sound, clean and correctly prepared area with enough room to operate the paver and rollers safely.

When paving can start before every kerb is finished

Large schemes are rarely built as one uninterrupted strip. A warehouse estate may need tenant access, fire routes and delivery windows throughout the works. The answer is phasing: finish a complete zone, protect it, pave it and move the traffic arrangement before opening the next zone.

That can put kerb installation in one part of the site and asphalt paving in another on the same day. There is nothing wrong with that when the work fronts are physically separated and neither operation relies on the other’s route. The problem starts when the paver needs to pass the kerb gang, asphalt wagons reverse through their working space or a roller is expected to compact an edge whose backing is still green.

A sensible phase boundary follows something buildable: a junction, a bay line, a drainage run or a designed pavement joint. A random stop because the access plan ran out of room creates awkward joints and leaves the next phase to repair the first.

Decide where the vehicles go before closing the lane

Traffic management is not a row of cones around the machine. It is a usable route from the estate entrance to every destination that must remain open, with holding points, turning space and a way back out. If two HGVs arrive together, both need somewhere safe to wait. If a tenant dispatches from the far unit, the driver needs a route that does not cross tack coat, fresh asphalt or the roller’s operating area.

The HSE guidance on construction site traffic management says vehicle and pedestrian routes must allow people to move safely, with suitable routes, safe crossings, clear instructions and separation where required. On a live estate, apply that thinking to tenant vehicles and visitors as well as the contractor’s plant.

Before the barriers move, answer these questions:

Which lane remains open, and is it wide and strong enough for the vehicles using it?
Where do arriving vehicles wait without blocking the public road or another tenant’s access?
Can an HGV turn without entering the paving zone or reversing through a pedestrian route?
Who controls a single-lane section, and can both ends communicate?
Where is the protected pedestrian route, including any necessary crossing?
How do emergency vehicles reach the occupied buildings throughout the phase?
What happens when an asphalt delivery arrives early or a tenant collection runs late?

If the work affects a public highway, the temporary traffic management needs the appropriate design, approvals and competent installation. The Department for Transport’s Traffic Signs Manual provides Chapter 8 guidance for design and operations in road works and temporary situations. A few site cones are not a substitute for the requirements that apply outside the gate.

Barriers have to close the tempting route

Drivers take the route that looks open. If a side entrance, gap between units or fresh binder course still appears to lead through, somebody will try it, especially at night or during a shift change.

The barrier line therefore has to make the closure obvious and continuous. It should protect the active paving area, close unused side access and support a clear diversion. Pedestrian barriers belong on the pedestrian interface; suitable traffic barriers, signs and controls are needed where vehicles are being directed or excluded. The arrangement must match the risk and the traffic management design, not just what happened to be on the wagon.

The open route also needs to remain genuinely open. Stockpiled kerbs, pallets, asphalt wagons and waiting plant cannot gradually narrow it until a driver has to mount a kerb or cross the work zone. Materials storage and wagon holding are part of the layout.

Drainage levels are the paving hold point

Before surfacing starts, walk the area with the levels in front of you. Check the kerb and channel, every gully frame, thresholds, crossings and tie-ins to existing asphalt. Confirm the planned surface can reach them with continuous falls and with enough compacted thickness to meet the pavement design.

This is the point to find a gully that is too high, not after the roller has finished. It is also the point to resolve a low crossing, a backfall at a dock approach or a kerb transition that would trap water. Our drainage gradients and falls reference is useful for an early sense check, but the project levels and drainage design govern the finished works.

The failures that come from rushing the sequence

The same avoidable defects appear when the programme drives the order instead of the construction:

Fresh kerb backing is damaged by wagons or the roller, leaving loose units and a weak pavement edge.
Asphalt is paved to an incorrect gully or kerb level, creating ponding that has to be cut out and reworked.
The paver reaches a pinch point with no safe roller path, so edge compaction becomes inconsistent.
A live vehicle crosses tack coat or fresh material because the diversion was not continuous.
The surfacing stops at an arbitrary point, leaving a joint in the worst possible wheel path.
Waiting delivery vehicles block the only route that was supposed to remain open.
Pedestrians step into the running lane because barriers protect the works but no bypass protects the people.

None of those is an asphalt problem on its own. They are interface problems between levels, access, temporary works and programme.

A final check before the first asphalt wagon

The last hold point can be short, but it needs to be real. Confirm that the kerbs and channels in the paving zone are complete and protected; drainage and ironwork are at the correct level; the receiving surface is ready; joints and tie-ins are agreed; barriers close every unintended route; the open vehicle and pedestrian routes are usable; and the paving train can enter, work and leave without crossing another gang.

That is how kerbs and asphalt belong on the same programme. Not side by side in a fight for space, but as consecutive operations inside a phase that has already decided where the water, machines, people and live traffic will go.

If an occupied yard or estate road needs resurfacing while access stays live, Rospower Projects can plan and deliver the drainage, kerbs, pavement repairs, surfacing and traffic phases as one external works package. See our industrial and commercial construction service or contact us to discuss the site constraints before the closure dates are fixed.

Eddie Lyons is construction director at Rospower Projects. He oversees civil engineering and external works across live commercial and industrial sites. Meet the team on our about page or contact us about an upcoming project.