2. Structures – Knowledge and Condition Assessment
There are approximately 33 500 road bridges in Australia and 17 000 road bridges in New Zealand in public ownership. More than 800 national, state and local agencies are responsible for managing those bridges. Each of these agencies is required to select an approach to bridge management to suit its particular circumstances.
At the time of publication there exists a draft data standard for road management and investment in Australia and New Zealand (Austroads 2016d) which gives guidance on data measurement and reporting for all road assets. This standard is aimed at ensuring that the data collected can support common operational activities of road agencies
For National and State Roads alone, the estimated replacement value of road bridges and major culverts in Australia and New Zealand at June 2014 was approximately A$48b and NZ$7.5b. Details are in Table 2.1.
In 2013–14, expenditure on maintenance of bridges on National and State Roads was estimated to be in the order of A$100m in Australia and NZ$15m in New Zealand.
Those amounts do not include the many more dollars invested and spent annually:
- by local government on its local road network
- on numerous other structures to which the principles of bridge management should equally be applied, e.g. minor culverts, noise walls, large sign support structures, geotechnical structures (retaining walls, rock anchors, gabion walls, protective beaching), tunnels (structural aspects only), etc.
|Road agency||Replacement value||Accumulated depreciation||Written down value|
|Roads and Maritime NSW||A$17.332b||A$5.196b||A$12.136b|
|Roads Corporation Victoria (VicRoads), VIC||A$8.216b||A$2.766b||A$5.447b|
|Department of Transport and Main Roads Queensland (TMR)(1), QLD||A$15.092b||A$4.942b||A$10.149b|
|Main Roads Western Australia (MRWA), WA||A$5.201b||A$1.473b||A$3.728b|
|Department of Planning, Transport and Infrastructure (DPTI), SA||A$2.114b||A$0.735b||A$1.379b|
|Department of State Growth, TAS||A$1.777b||A$0.538b||A$1.238b|
|Department of Infrastructure, Planning and Logistics, Northern Territory (DIPL), NT||A$1.108b||A$0.451b||A$0.657b|
|Transport Canberra and City Services Directorate (TCCS), ACT||A$1.134b||A$0.016b||A$1.118b|
|NZ Transport Agency (NZTA), NZ||NZ$7.489b||NZ$2.832b||NZ$4.648b|
- Valuation for 2014 based on escalation from 2000 values.
Source: Austroads (2000).
The challenge in highway structures management is to ensure that all structures in a road network remain fit for their intended purpose over long periods of time at minimum life-cycle cost. A comprehensive and effective management system is an essential tool to assist the responsible agency to meet this challenge by ensuring the reliability, safety and retained value of the asset.
Bridges and culverts managed by road agencies may serve a variety of functions, including carrying road traffic, rail traffic, pedestrians, cyclists, service ducts, etc. or providing a passageway for fauna. A road agency's bridges and culverts may be over waterways, canals, footways and cycle-ways, and under or over rail lines, other roads, and developed land.
In reviewing or establishing an asset management system, a road agency must therefore decide which structures warrant inclusion in its structures database. The main criteria for selecting assets to include in a road agency's structures database include the:
- need for structural engineering assessment for asset management purposes
- risk exposure to the road agency arising from defects in the structure
- stakeholder expectations for reporting by the road agency in relation to individual structures or generic collections of structures (e.g. by route, region, dominant structural type, age, etc.).
On this basis, a road agency should include in its structures database bridges, tunnels, culverts, large sign supports, retaining walls, and other roadside assets such as noise barriers. As a minimum, the database would include bridges and culverts meeting the agencies definitions (refer to Part 13).
Road agencies usually manage buildings separately from highway infrastructure assets.