The purpose of a Special Inspection is to provide detailed information on a particular part, area or defect that is causing concern, or inspection of which is beyond the requirements of the General/Principal Inspection regime.
A Special Inspection may comprise a close visual inspection, testing and/or monitoring and may involve a one-off inspection, a series of inspections or an ongoing programme of inspections. As such, Special Inspections are tailored to specific needs.
Special inspections are recommended for:
a. Cast iron structures, at intervals not exceeding six months.
b. Structures strengthened by the use of bonded plates, at intervals of six months for the first two years
and thereafter in accordance with the intervals prescribed in the maintenance records.
c. Structures that have weight restrictions, or other forms of restriction to reduce traffic loading, at
intervals not exceeding six months or as agreed by the Overseeing Organisation.
d. Structures that have to carry an abnormal heavy load. The structure should be inspected before, during and after the passage of the load if either:
• an assessment has indicated that the margin of safety is below that which would be
provided for a design to current Standards; or
• similar loads are not known to have been carried.
e. Structures in areas of mineral extraction, when subsidence occurs.
f. Structures if settlement is observed greater than that allowed for in the design. The cause should be
identified and steps taken to monitor the rate of settlement and to assess the urgency of remedial
g. Structures involved in a major accident, chemical spillage or fire. The inspection should investigate the
damage to the structure.
h. Probing of river bridge foundations after flooding. Where probing indicates the possibility of scour,
further Underwater Inspection should be carried out (see subsection 3.8).
i. Permanent access gantries prior to use and at intervals in accordance with The Institution of Structural
Engineers report on The Operation and Maintenance of Bridge Access Gantries and Runways.
j. Hoists, winches and associated cables. They should be inspected in accordance with the relevant
chapters of the Factories Act.
k. Post tensioned concrete bridges as described in BD 54.