A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle.
Council owned bridges typically exist to allow vehicles and/or pedestrians to access to areas that would be otherwise inaccessable or only accessable via a longer alternate route.
Glossary of Austroads Terms
The Glossary of Austroads Terms defines a bridge as a structure designed to carry a road or path over an obstacle by spanning it.
Victorian Code of Practice for Operational Responsibility for Public Roads
The Victorian Code of Practice for Operational Responsibility for Public Roads defines a bridge as any sturcture including culverts, on, over or under a road that have a single span or diameter of 1.8 metres or greater, or have a waterway area of 3 sq.m. or greater and includes all structural components (eg. abutments, retaining walls, traffic safety barriers), and associated pathways, within the limits of the structure, but excludes approach embankments.
Types of Bridges
Wikipedia lists six main types of bridges: beam bridges, cantilever bridges, arch bridges, suspension bridges, cable-stayed bridges and truss bridges.
The majority of new local government controlled bridges are probably constructed from pre-cast concrete segments. Timber was a common bridge construction material in the past, and is still used in the construction of footbridges, but it is not common for new road bridges to be constructed from timber.
Bridges are sometimes broken up into several components in an asset register, including;
The useful life of a bridge will depend on the type of bridge, the material from which it is constructed and a range of environmental & other factors. A life of 30-100 years is typical for bridges channel in some areas.
The maintenance of timber bridges is an issue for many rural Councils. Fortunately the Queensland Main Roads Timber Bridge Maintenance Manual, which can be downloaded free of charge from the Main Roads website covers the maintenance of timber bridges in great detail.
As with other timber structures, timber bridges should be checked and treated for termites on a regular basis.
Condition Assessment Techniques
There are a number of Condition Assessment Techniques that can be applied to bridges, including;
- Visual Condition Inspection
- Test Drilling
- Resistograph / Drill Resistance
- Ground Penetrating Radar
- Stress Wave Non Destructive Testing
- Vibrational Analysis
- Diagnostic Static Load Test
- Asset & Component Types
- Bridge Asset Management System
- Bridge Inspection
- Bridge Load Limit
- Level 1 Bridge Inspection
- Major Culvert
- Transport Infrastructure
External Links & References
- Wikipedia Article
- Bridge Management & Evaluation (ARRB)
- Timber Bridge Management (NSW RTA)
- Google Wave Timber Bridges Discussion
- Trial of Ground Penetrating Radar to Locate Defects in Timber Bridge Girders
- Nondestructive Evaluation Techniques for Timber Bridges
- Queensland Main Roads Timber Bridge Maintenance Manual
- Victoria's Arterial Bridge Strategy (VicRoads)
- Short Span Steel Bridges - Myths and Realities
- Bridge Construction Methods (David Trayner)
- Design Rules for Bridge Bearings and Expansion Joints (Austroads)