Roading Improvement Works
Our network is continually assessed to determine where and how improvements can be carried out and all works considered are controlled by the availability of funding for the work.
The types of renewal and new capital works are:
· Cyclic Renewal
· Maintenance Metalling
· Pavement Treatments
· Drainage Improvements
· Bridge Upgrades
· Traffic Signs
· Street Lights Upgrade
· Other New Capital Works
Renewal (Cyclic Renewal) works
This is cyclic renewal work on unsealed roads that have lost most of their existing basecourse through a combination of road grading and basecourse deterioration due to traffic on the road. Annually the length of work carried out covers about 30 km and involves 37,000 cubic meters of basecourse. The roads in the Ashburton district network that require this treatment are effectively upgraded on a 20 year cycle.
Area wide pavement treatment
Council has adopted a policy to upgrade the busier unsealed roads by proper reconstruction of the base course along with associated roadside drainage. The work involves application of design depths of basecourse to carry current traffic loads and topping off with a layer of clay bound top course to provide a bound, smooth running surface. This wearing course will eventually be removed by regular traffic movement and at that stage the road may be sealed, subject to available finance. Approximately 30 km of roads are being treated with this work annually.
Major drainage improvements
This work covers replacement of existing kerb and channel where this has failed and is affecting the integrity of the road adjacent to the kerb. New kerb and channel is placed on the line of the old kerbing and drainage disposal systems upgraded. This section also covers the installation of roadside drainage improvements in the form of swales (shallow dish drains), primarily required to remove the water from off the road surface and onto the grassed areas, along with the installation of soak holes. Culvert upgrade and installation of new culverts under roads to assist with stormwater control is also a continual process.
The sealed roads are resealed on a cyclic basis to retain the surface integrity. The bitumen in the road oxidises over a 12-15 year period and becomes brittle. This makes it prone to pothole formation and surface cracking. Both these failures allow water to penetrate the road structure which, when combined with traffic movements, will accelerate the failure of the roads. The sealed roads are resurfaced every 12 years on average and 122 km of new seal is applied each year. Reseal Programme 2007/2008 is available for download.
The district has 161 bridges and shares ownership of an additional 24 bridges with the Rangitata Race Diversion Company (RDR). Eight of these have weight and/or speed restrictions. Two of these are currently being rebuilt to a standard where restrictions will be unnecessary. The programme will eventually see the removal of all weight restrictions on bridges.
The council is nearing the end of a complete upgrade of all road name signs in the district, both rural and urban. This is expected to be completed in 2003/2004. The new road name blades will be reflectorised blue signs with the road name and block numbers on them. (Rapid numbers for rural areas and street numbers in urban areas).
Street light upgrade
In 2003/2004 Council will complete upgrading of all street lights in the district from mercury vapour lamps to high pressure sodium lamps. The new lamps are more energy efficient and provide nearly four times the level of visible light for the same energy input.
New capital works
For major new works to obtain funding assistance from Transfund New Zealand Ltd the cost benefits from the project must be at least four times higher than the cost of the project (based on approved project evaluation procedures). Most of our district roads have low traffic counts and it is difficult to prove that the level of benefits will exceed the costs by the required factor. This means that Council generally has to fund the cost of new work from its own sources, usually rate funded. As a result, projects such as seal extension have a direct effect on the level of rates charged in the district and have to be matched and prioritised against other works also funded from this source.
There is a budget area where small works that improve the level of road safety may be funded. This totals about $240,000 per annum and approximately 12 separate projects are carried out each year. There must be an element of safety improvement in the project and the cost of an individual project may not exceed $75,000 to be eligible for this funding. Works carried out under this provision include intersection upgrades (eg roundabouts in Oak Grove/Walnut Ave), safety footpaths, new street lights with power line undergrounding, pedestrian kerb protrusions and new street lights at rural intersections.