Step 3: Preparing for Bridge Inspections
Bridge Inspection requires certain basic preparation before launching the inspection program. This generally includes timing of the inspection, access to bridges, safety measures to be taken at the time of inspection, transport to be used for purpose of inspection, equipment to be taken for use during the inspection and bridge data (i.e. background data about the specific bridge) inspection forms to be taken for inspection depending upon type of inspection, and a briefing on the approach to be adopted, Refer ▬►Guidelines for Inspection and Maintenance of Bridges Volume-1, Part -2, , Bridge Inspection Manual, Chapte -3,Page 32-34.
3.0 PREPARING FOR BRIDGE INSPECTIONS
It is essential that bridge inspections are properly planned, otherwise they will fail to fulfill their purpose. When preparing for an inspection the following matters need to be addressed.
3.1 Timing
Inspections should generally be carried out during the dry season when water levels are low and rivers may even be completely dry. This will permit easier access to midriver piers, and will allow the river bed and any bed protection to be inspected. It will also enable scour damage to be inspected. Inspection by the Maintenance Divisions will need to be coordinated with their general maintenance activities to ensure that the appropriate staff are available to carry out the inspections.
Other seasonal factors need to be considered, for instance avoiding intense midday heat in hot months, and ensuring that there is sufficient daylight available. Advantage should be taken of any circumstances which will facilitate the work such as scaffolding for repair work on the bridge or the closure of roads or traffic lanes for road works. For the first Principal Inspection on a new structure advantage should be taken of the Contractor’s access equipment before it is demobilised.
3.2 Access
The means of access to the bridge needs careful consideration. In many cases access to much of the structure is available on foot, but ladders will normally be required to enable bearings at the tops of piers and abutments to be inspected. Where bridges are located across permanently flowing rivers it may be necessary to use a boat. If the river is fast flowing strong securing ropes may be necessary, and inspections may need to be carried out in a particular month to take advantage of slower flows.
High level bridges also present difficulties. In some cases it may not be possible to obtain access to the underside of the deck or the tops of the piers without special equipment, and inspections may have to be undertaken from the ground using binoculars until such time as access equipment becomes available.
3.3 Safety
Bridges are potentially hazardous places and safety - of the bridge inspector, road users and local residents - must be given the highest priority. Bridges will normally be inspected while traffic continues to use the bridge, so there is the obvious danger to the inspector due to moving vehicles. There is also the potential danger of tripping and falling from the bridge, or of dropping equipment from the bridge onto people below. Another possible source of injury arises from insect or snake bites. All of these dangers can be avoided provided suitable precautions are taken. Bridge inspections should not be undertaken alone - the inspector should always take an assistant who can summon help in case of emergency. Temporary signboards should be used during all bridge inspections to notify drivers and pedestrians using the bridge that inspection work is in progress. Bridge inspectors should always have a first aid kit available on site. Please refer to departmental safety guidilies as described Reading the safety guidelines can save a life.
3.4 Transport
Suitable transport should be arranged to enable the inspector to get to the bridge site, together with all necessary equipment and assistants. Ladders will generally be required and provision needs to be made to carry these.
3.5 Equipment
The following items of equipment should be provided for all inspections apart from Superficial Inspections:-
| Traffic warning signs |
Penknife |
| High visibility fluorescent waistcoat |
3 m steel tape |
| Protective clothing |
30 m steel tape |
| Safety helmet |
Mirror |
| Clipboard (waterproof) |
Haversack / shoulder bag |
| Writing materials |
Plumb line |
| Waterproof marker |
Ranging rods (for probing depth of scour) |
| First aid kit |
Hammer |
| Binoculars |
Crack width gauge |
| Camera, flash and film Torch |
Ladder |
The following additional items may also be required:-
- Jars / plastic bags for samples
- Screwdriver
- Spirit level
- Straight edge
- Small boat
The inspection and/or access equipment requirement is enhanced for Principal and Special Inspections. Appendix E gives an indicative guide to specialist inspection equipment that may be used from time to time.
3.6 Bridge data
Before starting the bridge inspection the engineer should look up the data on the Bridge Inventory Record Card held by the Divisions (a copy of which is also held by the Regional Office and the Bridge Unit). This gives basic details of the structure such as size and number of spans and structural form, which will help the engineer to plan the inspection. The engineer should also inspect a copy of the last bridge inspection report and take a copy of the Summary Sheet where appropriate.
3.7 Inspection forms
It is good practice to prepare and collate the inspection forms and to fill in the details from the Inventory Record Card before going to site. This is easier to do in the office and saves time on site.
3.8 Briefing
Before inspecting a bridge the inspecting engineer should check with the Divisional Engineer whether there are any special instructions - for example inspecting previous repair work and reporting on its effectiveness.