Manual for Highway Bridge Maintenance Inspection
1996 Edition

As per IRC SP 18, typical inspection schedules for highway bridges are:

• Standard bridges should be examined annually by a qualified engineer.
• Bridges located in mountainous or landslide-prone regions require biannual inspections — one prior to and one following the monsoon season.
• Major or specialized bridges, including prestressed concrete continuous spans, suspension, and cable-stayed bridges, must be inspected by senior engineers with relevant expertise.

These schedules help ensure early identification of defects caused by environmental and structural factors.

Summary Table:

According to IRC SP 18, bearing inspections during extreme environmental conditions should be conducted:

• At temperature extremes to monitor maximum allowable movement of bearings and expansion joints.
• After flood events and during peak flood conditions to assess scour and foundation stability.
• Following unusual occurrences such as earthquakes, abnormal traffic loads, or unprecedented floods.

Inspection focuses include:

• Metallic bearings: Check for deformation, corrosion, lubrication status, and alignment.
• Foundations: Measure scour depth using soundings or weight-on-wire techniques during floods, and inspect for cracking, erosion, cavitation, and impact damage after floods.

Critical periods for inspection include monsoon seasons, strong wind seasons, and after seismic or heavy load events.

Any inability to inspect due to water presence must be noted, and remedial actions recommended if scour exceeds design thresholds.

IRC SP 18 recommends the following procedures for scour assessment:

• Conduct inspections during high flood stages to determine maximum scour depth and compare it against design criteria.
• Perform regular soundings around foundations, especially well foundations, employing wire-weight gauging if advanced equipment is unavailable.
• Pay particular attention to rock-based foundations with scouring overburden.
• After floods, inspect for structural cracking, erosion, cavitation, and damage from floating debris.
• Examine protective works like guide bunds, spurs, pitching, and aprons for damage or settlement.
• Verify availability of reserve stone materials onsite for timely repairs.

These practices ensure foundation safety through continuous monitoring and timely intervention.

The manual identifies the following critical defects necessitating immediate remediation:

For Prestressed Concrete Members:

• Loss of designed camber or excessive deflection.
• Buckling or distress of structural elements.
• Cracking or spalling near bearings and diaphragms.
• Corrosion of prestressing strands, especially at anchorage points.
• Concrete deterioration including spalling, honeycombing, or disintegration.

For Structural Steel Members:

• Corrosion and cracking.
• Loose or damaged connections including bolts, rivets, and welds.
• Misalignment, buckling, or damage of webs and flanges.
• Deformations such as kinks, bows, or eccentricities.
• Loss of camber in main girders.

For Bearings:

• Excessive displacement, tilting, or displacement from guides.
• Cracks in supporting components like abutments or pier caps.
• Deterioration such as oxidation or creep in elastomeric pads.
• Cracking or spalling in concrete bearings.

Prompt action on these defects is essential to maintain safety and structural performance.

The manual advises the following for expansion joint inspection and maintenance:

• Inspect the integrity of joint seals, checking for cracks, wear, or displacement.
• Verify the joint's ability to accommodate thermal expansion and contraction as designed.
• Examine for corrosion or damage to all joint components.
• Ensure effective drainage through the joint to prevent water ponding.
• Remove debris or obstructions that may hinder joint function.

Maintenance includes cleaning debris, repairing or replacing damaged seals, lubricating moving parts if necessary, and ensuring proper alignment and anchorage. Periodic inspections are especially important after severe weather or seismic events to preserve joint flexibility and watertightness.