Safety message: Managing your bridge assets

> Asset details

Asset details (such as an asset register) provide information about the bridge itself. Information that asset details should cover includes, but is not limited to:

• Structure and location name, and location rail kilometrage (normally given at the "Up" end of the bridge)
• Structure description including number of spans, lengths of spans, super-structure type, sub-structure type, and deck configuration, for example, transom, ballast top or direct fix.
• Structure drawings and photographs including design railway loading (original design live load and current live load rating (LA) equivalent), structural details of any modifications or strengthening.
• Current operational railway loading details e.g. showing maximum axle loads, load or speed restrictions, and typical operational rollingstock type in use.
• Current operational speed and temporary speed restriction (if any).

> Indicative risks and controls

Documenting the risks and controls for bridges demonstrates that risks are being monitored and managed effectively. Risks can include:

• Structural collapse due to:
  • overloading of the bridge,
  • deterioration of a bridge member (rust, rot, split, crack, fatigue, insect attack).
  • deterioration of the bridge due to an external event (scour at supports, landslip, wind event, flood or earthquake damage, bridge struck by road or rail vehicle damage to the bridge due to derailment of train on approaches or on the bridge.
• Railway staff or passengers falling from the bridge.
• Bridge inspection staff or repair crews struck by road vehicle or train.

Each of these risks should have controls in place to ensure the safety of the bridge so far as is reasonably practicable. These controls can include:

• Design based on appropriate standard and performed by a qualified bridge engineer.
• Design is verified, and construction certified.
• Bridge design load recorded and current train load effects are less than design capacity.
• Current structural condition is checked by routine and special inspections, defects are recorded, risks evaluated and monitored with interventions made before defects become safety critical.
• Special engineering inspections in the event of earthquake, flood or other damage - to confirm adequacy of structure or initiate necessary repairs.
• Maintaining the track and rollingstock to standards.
• Adequate design clearance, signposting of any reduced clearance, addition of crash beams to protect the bridge structure, adoption of active monitoring and warning system for over-height vehicles (as required by risk analysis).
• Train loading standards, competency of personnel and inspections.
• Workplace safety procedures and worksite protection for road and rail traffic.

> Systems and Procedures

Procedures underpin the overall process for maintaining bridges. They can include:

• Competency requirements for bridge inspectors, and bridge engineers.
• An identified responsible and competent person to make asset decisions.
• Clearly defined responsibilities of Inspectors and Engineers.
• Inspection types, frequency and methodology required.
• Previous report and photographs of defects on site to ensure consistency and capacity to review any deterioration.
• All structural areas to be inspected, access proximity and any tests required for inspection types.
• Defects to be checked for (depending on structure type and materials) including their priority rankings, defect criticality limits (with triggers for higher inspection type)
• Clearly defined safety critical structural defect limits that inform restriction to, or suspension of, railway operations.

> Structural standards

Standards define the criteria for how bridges should be maintained. They can include:

• Australian Standards (e.g. AS 5100 Bridge Design and relevant material standards)
• RIM assets systems, bridge inspection standard and procedures
• RIM bridge maintenance procedures
• RIM structural defects management process
• RIM and road authority Safe Working Standards
• Clear and defined defect acceptance and rejection criteria
• Priority ranking system for defects
• Technical maintenance plans

> Inspection records

Undertaking inspections of bridges helps understand their condition and what repairs or maintenance may be required. Documentation in relation to inspections can include:

• Type of inspections:
  • Level 1 (routine visual inspections)
  • Level 2 (detailed inspection and testing)
  • Level 3 (detailed engineering inspection and load rating).
  • Special engineering inspection triggered by external events.
• Structural areas to be inspected, access proximity and any tests required for inspection types including whether they meet standards.
• Triggers for L2 and L3 inspections e.g. significant defects, deteriorated bridge condition.
• Special inspection report triggers e.g. storm damage, train derailment, landslip, increased loading or operational speed proposed
• Copies of all previous inspection reports (L1, L2, L3 and special)
• Timing for inspections e.g. when next inspections are due (L1, L2 and L3)
• Inspection forms to be used.

> Defect management

Defect management is about ensuring defects or non-conformances are accurately recorded, criticality assessed, tracked, monitored and actioned, ensuring traceability from defect to rectification.

Information in relation to defect management can cover:

• Itemised current defects (as per TMP)
• Defects referenced to specific structural element as per description/numbering system adopted in standards.
• Key details about the defect including:
  • date found, inspection type (L1, L2, L3, or special), defect type, detailed location, photographs
  • current criticality assessment
  • programmed future action (monitoring frequency, correction date, more detailed inspection if nearing intervention limits)
• Next inspections due (L1 and L2)
• Documented changes made by structure’s manager to inspector’s draft
• Defect criticality and draft correction date, with reasons and any additional risk controls deemed relevant.
• Records of repairs made and assurances these can be related and traceable to the relevant defects and non-conformances