Our Guide to Highways

Road maintenance types

We use various different types of road maintenance techniques, and our experienced highway engineers select the most appropriate and cost-effective technique to suit the circumstances:

  • Planned, preventative maintenance will extend the life of roads by sealing the surface and protecting it from damage caused by water and UV light. Preventative maintenance usually involves no replacement of material unless minor repairs are required in advance.
  • Intervention maintenance treatments are required if the surface of the road has deteriorated beyond preventative treatments but the base below is still in good condition. We remove the surface layer and replace with new.
  • Structural maintenance is required if the road base has broken-down and requires replacement of base layers in addition to the surface layers.

Layers of a modern carriageway:

  1. Surface Course
  2. Binder Course
  3. Base
  4. Sub Base

Did you know 55% of our roads are rural lanes and estate roads. Most of our rural lanes are not built like modern roads, they have evolved over time from ‘unmade’ tracks but have later been surfaced with asphalt.

Preventative maintenance types

Micro Asphalt - Preventative

A cold-applied thin bituminous surface course incorporating bitumen emulsion and fine graded aggregate with fillers, Micro-surfacing incorporates a polymer modified bitumen emulsion and is often a two-coat application and can be laid mechanically or manually to a maximum dried film thickness of 15mm. A Micro Surface restores surface texture and improves skid resistance, prevents ingress of water into the road structure, seals and preserves existing surfaces and has the ability to reshape and re-profile existing surfaces.

Crack sealing and joint repair

Crack sealing and joint repair help to maintain a road surface in a safe and serviceable condition and extend life. Left untreated, cracks and open joints in the road allow water ingress which will create further damage and ultimately shorten the life of the road. Timely intervention using crack sealing and joint repair systems can both seal the surface against the ingress of water and reinstate the surface profile.

Surface Dressing

A layer of liquid bitumen is sprayed onto the road surface to seal it and provide a binder for stone chippings which are then spread on top. The road surface is then rolled to embed the chippings. This provides enhanced skid resistance, and prolongs the life of the road by up to 10 years by preventing water damage to the underlying structure.

Excess chippings are then swept approx.  24 hours, 3 day and 7 days after the works are carried out.


A cold spray-applied surface penetrative preservation sealer, preservative penetrates into the asphalt mortar at the surface. This provides a durable seal to prevent water ingress and retards further oxidization of the road from water and UV light.

It preserves the condition of the surface at the point of treatment and provides improved cohesion and binding properties with the aggregate matrix.

Preservative is best utilised as a preventative maintenance measure as part of a long-term asset management strategy, extending the operational life of the road and delaying the large costs of resurfacing and repair works. Preservative is a cost effective treatment to keep good roads in good condition for longer. 

Intervention maintenance types

Plane and Inlay

If the road surface requires replacement and cannot be overlaid due to levels or condition the surface layer can be mechanically removed (Planed), a tack coat is then applied before re-laying a hot bituminous material to create a new road surface.


As long as existing levels are suitable it is sometimes possible to apply a new surface course directly on top of the existing with minimal or no patching we call this an overlay. This technique provides a greater thickness of bound surface and is often more cost effective than replacing. This is a surface repair only, and can only be done where there is no damage to the existing road structure (small isolated areas can be patch repaired in advance). Overlaying is often the first process considered when surfacing a carriageway as this takes advantage of the materials already in place, strengthens the road and is the least disruptive.

Structural maintenance types

Structural Road Recycling

Structural Road Recycling restores a failed road by recycling and reusing the existing construction materials to construct a new road base with strength and life expectancy that is equal to that of a traditionally designed and reconstructed road. The need to dispose of huge volumes of waste materials, import new aggregates and hot bituminous bound material is greatly reduced resulting in a lower carbon footprint and lower cost. The Structural Road Recycling process is also a convenient method of dealing with ‘tar’ residues in road construction, as the resultant recycled mix encapsulates the hazardous contaminants, rendering them harmless to the environment and avoids the need to remove them by excavation for disposal in a licensed hazardous waste facility.


An expensive treatment and is used as a last resort when the road surface and underlying layers have deteriorated to an advanced stage. Repairs may involve a deep excavation, and replacement of the sub-base stone layer in addition to the upper bituminous layers.

Other maintenance types

Retexturing – Restores skid resistance

This is the mechanical reworking of a sound road surface to restore skid resistance, texture depth or both, achieved by roughening the worn surface. The surface levels of an area which have been retextured will remain the same as the surrounding surface. Retexturing can be done hydraulically by blasting water at the road surface or mechanically by different methods which involve impact cutting or milling.