Rebuilding A Road

Road reconstruction includes a variety of activities like overlays, rehabs, shape corrections, minor safety improvements and repairs; but typically not actually building a new road.

Currently we have 5000km of formed roads and the only new road to have been constructed (outside of property development) in the last 30 or more years has been Papatotara Coast Road, necessary because the old road fell into the ocean!

So more of what happens is that we maintain, repair, rebuild or upgrade existing roads to meet the required level of service for the community.

Stages of road reconstruction

In general terms, gravel and sealed roads are very similar in their construction as they go through a series of stages: 1-4 for unsealed roads and 1-8 for sealed before being considered complete.

Stage One

Pre-construction: This involves the identification, design, tendering, acceptance, first site meetings, documentation transfer and Traffic Management. 

Left: A walk through with the contractor to outline the purpose and expected outcome.

 

 

 

 

Traffic Management Plans are approved. 

Stage Two

Drainage/Earthworks: The most significant stage of construction is the basis/foundation that the road is built upon (and usually where problems evolve from).  Here we remove existing vegetation, reshape/build the drainage, instal culverts, soak holes, sumps, subsoil drains etc.

 Left: Remove broken culverts and replace with new pipes.

Right: Remove overgrown vegetation from shoulders and improve drainage.

Stage Three

 

Rockfill/Bulkfill: Now that unsuitable material has been trimmed out it is time to start reconstruction. At the outer edge of the carriageway (not trafficked lane/shoulder) rockfill and bulkfill are used to raise and align to design levels as per plans, then compacted into place with rollers.

 

LEFT: Placing rockfill to shoulders over drainage

 

 Stage Four

Sub base: AP65 (65mm or other specified grade of aggregate suitable for task) is placed on carriageway and shaped using a grader to the necessary fall. On a straight section of road this is typically 3%. It is then rolled and compacted and the grader and roller make repeated runs to achieve the designed shape.

LEFT: Sub base to carriageway complete  

THIS IS THE END OF CONSTRUCTION FOR UNSEALED ROADS (go to Stage Nine - Completion)

Stage Five

 

Base course: AP40 (40mm or other specified grade of aggregate suitable for task) is placed over sub base and shaped.

LEFT:  Placing and grading of base course

 

  

 

Stage Six

Running Course: With the base course complete, an application of running course (a fine grit material) is spread over the site using a drag broom, filling in any small voids and protecting the base course layer underneath from traffic using the yet unsealed road.

LEFT: Drag broom being towed behind vehicle to smooth surface, ready for sealing.

 

Stage Seven

 

Sealing: With construction completed satisfactorily, approval is given to the contractor to seal the road surface with bitumen and a grade of sealing chip suited to the road and its use. For example, many roads will receive a single coat of chip (grade 3 medium); however, on heavy vehicle accessways, intersections and steep inclines an extra coat is often applied (2 coat grade 3/5 medium then fine).

LEFT: Spreading of sealing chip over bitumen

 

 

 

Stage Eight

Pavement Marking and Furniture: With the sealing complete and excess chip swept, the road is ready for pavement marking (centre lines, edge lines, intersection markings, etc) and the installation of furniture (edge marker posts, culvert markers, stop signs, curve warning signs, etc).

Stage Nine

Completion: The contractor advises Council that work has been completed and requests Practical Completion. It is the responsibility of Council's representatives (either an Area Engineer, Roading Manager or Consultants) to check the site has been satisfactorily completed and that the outcome meets the specifications of the contract.  Once this has been achieved, Practical Completion can be issued, a 12 month maintenance period begins, and another construction contract is complete. 

Farmers - you might want to take advantage of road works in your area next and have your accesses shaped and sealed.  Please contact either your Area Engineer or the Contractor.