Highway Maintenance

Highway Structures Policy

4. Inspection of Highway Structures

4.1 General

4.2 Categories

4.3 Frequency of Inspection

4.4 Inspection of small pipes, culverts and other footbridges

4.1 General

4.1.1 The purpose of carrying out inspections is to ensure the safety and long term serviceability of all Highway Structures.

4.1.2 All bridges and Ancillary Structures and certain Footbridges included in the database for which the Highway Authority has maintenance responsibility shall be programmed for inspection at least once every year, preferably during the spring or early summer. Before the start of each financial year, Bridge Client staff will advise Highway Units/Engineering Consultancy of the county bridge inspections which they are to carry out in that year. All inspections on county structures shall be completed and returned to the Bridge Client before the end of September.

4.1.3 Previous inspection reports shall be reviewed and any maintenance work carried out noted, before carrying out Principal or General Inspections.

4.1.4 Prior to Principal Inspection, a database printout for the bridge shall be provided for reference during inspection. The information shall be checked, completed and amended as necessary. The updated information shall be input into the database.

4.1.5 When an inspector identifies maintenance items prioritised as ‘Emergency’, he (or she) shall immediately report the defect to the Bridge Client by the quickest means available. He shall confirm verbal advice in writing at the earliest possible date thereafter; Fax, Profs or completed report are acceptable. The member of the Bridge Client receiving the report shall ensure that appropriate action is taken.

4.2 Categories

The various levels of inspection are categorised and defined as follows:-

4.2.1 Superficial Inspection

The purpose of a superficial inspection is to identify and report daily obvious defects which, if ignored, might lead to collapse, accidents or high maintenance and repair costs. The inspection will normally be carried out by Highway Unit staff.

4.2.2 General Inspection

This inspection requires the examination of all parts of the structure that can be inspected without the use of special plant, scaffolds, etc. Visual aids such as binoculars shall be used where necessary. Where the bed of a river is susceptible to scour, a check for scour/undermining of structural foundations shall be made, using a boat if necessary. General inspections will normally be carried out by Engineering Consultancy staff.

4.2.3 Principal Inspection

Each Principal Inspection shall normally be carried out by a member of the Engineering Consultancy staff who is a Chartered Engineer and/or has at least 10 years experience of bridge inspections. This inspection shall include checks for scour as in General Inspections and requires the detailed examination of all inspectable parts of the structure. Special access plant, scaffolding, boats etc, shall be employed as necessary to gain close access for effective detailed inspection. Database checks shall be carried out and colour photograph records of defects obtained together with bridge elevations if not on file.

Where an element of a structural steelwork bridge shows signs of severe local corrosion, residual laminated paintwork and loose corrosion must be removed and residual section thicknesses checked. The report should note if an assessment of the member structural adequacy and load capacity of the bridge is considered necessary.

4.2.4 Special Inspection

Special inspections are inspections carried out in addition to planned maintenance inspections. They are arranged as required by virtue of the condition of the structure or in connection with abnormal load movements, flooding, accident damage, etc.

Area/District Engineers are responsible for carrying out initial inspections of river bridges after exceptional rainfall or flooding and of damage to bridges from vehicle accidents. In the case of river bridges after flooding conditions, particular regard should be given to movements, settlement of foundation and approach training walls and the removal of waterborne debris.

Where a bridge has been damaged or where the integrity of the bridge is considered to be at risk, the Chief Bridge Engineer should be requested to arrange for a more detailed Special Inspection.

The Bridge Client shall ensure that lists of bridges potentially at risk due to flooding are available for immediate reference by each Area/District Engineer. The Bridge Client shall arrange for Area/District Engineer to be reminded of their responsibility at appropriate times where abnormally high river levels and/or flooding occurs.

4.3 Frequency of Inspection

4.3.1 Bridges and Ancillary Structures

Generally bridges and ancillary structures will be subject to inspection on a six year cyclic basis, the sequence being as follows:

Year 1 Principal inspection by Engineering Consultancy staff

Year 2 Superficial inspection by Area/Agency District staff

Year 3 General inspection by Engineering Consultancy staff

Year 4 Superficial inspection by Area/Agency District staff

Year 5 General inspection by Engineering Consultancy staff

Year 6 Superficial inspection by Area/Agency District staff

Bridges and ancillary structures on the six year cycle are allocated an inspection cycle number between 1 and 6. The inspection cycle number gives the year in which a principal inspection is to be made, year 1 being 1990. Other inspections will follow in sequence. Thus, if a bridge has inspection cycle number 5, then a principal inspection will be carried out in 1994 with the next one due in year 2000.

In the case of new structures the first Principal Inspection shall be made as soon as practicable after the structure is completed and where possible it should coincide with the inspection carried out at the end of the Contract maintenance period.

Structures which require inspection by divers shall normally be inspected on a two year cycle to coincide with Principal or General Inspections.

4.3.2 Private Structures

The highest category of inspection for Private Structures will be the general inspection to be carried out at two year intervals. This takes account of the fact that the County Council have no responsibility for maintaining the structure. The purpose of the inspection is to ensure that it is maintained by the owner to an adequate standard to ensure the safety of highway users.

4.3.3 Footbridges

Most footbridges for which the Planning and Transportation Committee are responsible, together with certain bridges on footpaths and bridleways for which Heritage and Recreation are responsible, will normally be inspected on a three year cycle. Every third year a general inspection will normally be carried out by Engineering Consultancy staff. Other inspections are superficial and shall be carried out by Highway Unit staff. Inspection cycle number 7, 8 and 9 are allocated to such structures, bridges referenced 7 having General Inspections in 1993.

Large more significant footbridges such as those spanning railways and roads are separately identified within the database and will be subjected to the same inspection regime as "Bridges and Ancillary Structures" (see para 4.3.1).

4.4 Inspection of small pipes, culverts and other footbridges

Where details are known small pipes and culverts which fall outside the definition of ‘bridges’ and footbridges not covered by section 4.3.3 are included in the database of Highway Structures. They are allocated an inspection cycle number zero and are not routinely inspected by Engineering Consultancy staff.

Chief Engineers – Highway Units or Countryside and Community arrange for inspections and routine maintenance as required.

Version No:   1.0

Effective:   From - 21/04/2004

If copied or printed, this document should be treated as uncontrolled and correct only at the date it was copied or printed.