LeftNavigation
  Home  
  General Job Description  
  Specific Job Descriptions  
  Strategy  
  Operational Plan  
  Rules and Regulations  
  Operational Procedures  
  Databases  
  Active Tenders  
  Online Documents  
  RHD News  
  Search  

 

 

RHD Operational Procedure – Bridge Management Wing
 
Planning and Data - Bridge Maintenance Programming Division
 
OP/PD/3.3 - Prioritising Quality Standards for Bridge Maintenance and Management
 
Purpose and Scope :

The Bridge Management Wing, through liaison with RHD Wings and Field Divisions, has an objective to ensure all bridges are “appropriate maintained to optimise use of funds”.

The aim of maintenance is to ensure that bridges are safe, able to carry the imposed traffic loading and that preventive measures are taken to reduce or eliminate future large-scale maintenance or replacement costs. However this has to be achieved within a limited budget requiring an effective prioritisation of expenditure.

This procedure sets out how the BMMS is used to enable engineering judgement, to be the basis for systematic prioritisation for bridge maintenance and rehabilitation, for all damaged bridges and box or slab culverts on the RHD Network.
 
Definitions :

Bridge Management and Maintenance System (BMMS) – is a database established containing condition survey of all bridges and culverts of RHD road network and is used in bridge planning, design and management role. The system has provision for prioritising maintenance and replacement needs based on a number of set parameters.

Routine Maintenance (RM) – works of bridges & culverts include regular cleaning of the structure, minor repair of approaches, clearing small obstructions in the channel, replacing damaged guide posts, railing, signboards, etc.

Periodic Maintenance (PM) – works of bridges and culverts will include (1) major repair and protective works up to a value set by the CE, RHD annually and (2) replacement works up to a value set by the CE annually. These works will generally be carried out through Revenue Budget.

Rehabilitation – (replacement) works will include any work exceeding the set value mentioned in (1) and (2) above.

The following definitions of Probability, Consequence and Risk of failure are for the purposes of this procedure:

Probability of Failure – is a number derived from various factors indicating the susceptibility of total structural failure, relative to other RHD structures assessed in the same manner- how likely failure is.

This prioritization facility will be integrated within facility BMMS during 2004/2005

Consequence of Failure - is a number derived from various weighted factors indicating the overall consequence of total structural failure, relative to other RHD structures assessed in the same manner-how bad failure would be for Bangladesh.

Risk – is defined as Probability of Failure multiplied by Consequences of failure.

Weighting - is the relative sensitivity of different factors (% variation). Factors with a higher weighting will have greater influence on the Risk calculated.
 
Responsibility :

Additional Chief Engineer - Bridge Management Wing (ACE-BMW) – Agrees the factors to be used in both Probability of Failure and Consequences of Failure for systematic prioritising of bridge and culvert maintenance and bridge replacement.

Superintending Engineer - Planning & Data Circle (SE-PDC) – Presents to the ACE-BMW proposals for factors to be used to calculate the Probability of Failure and Consequences of Failure and the Weightings used in assessing Risk.

Executive Engineer - Bridge Maintenance Programming Division (EE-BMPD) – Based on the various factors and weightings, runs a pilot study and (in consultation with the pilot division) based on prioritisation, recommends any revision to the factors and weightings to SE-PDC that he believes appropriate.
 
Method :

4.1 PRIORITISED SYSTEM

To define and quantify Risk it is necessary to quantify Probability of Failure, Consequence of Failure and the Weighting between the various consequences of failure.

4.2 PROBABILITY OF FAILURE

The probability of failure of a structure is a function of a number of factors. Such factors include:

· used Condition of the structure

· Age and live loads imposed on the structure

· Materials in construction

· Exposure to saline attack, common in coastal areas (some materials)

There may be more factors that could be considered. However, the above are readily available, and adequate for the purposes of prioritising.

As these factors are independently related to the probability of failure, they have been multiplied together to give an overall probability of failure. The weighting of each has been determined by basing the variation of each factor by its likely effect in real terms (e.g. an old heavily loaded bridge is move likely to fail than a lightly loaded new bridge).

The factors are included on the database shall be reviewed once a year prior to prioritisation and agreed.

4.3 CONSEQUENCES OF FAILURE

The Overall Consequences of Failure is considered as the sum of a number of different consequences:

· Direct Human impact – death or injury as a result of structure failure

· Effect on Local Access (in direct human impact)

· Effect on National Road Network (economic impact of diversion)

· Replacement cost (to RHD)

· Effect on access to areas prone to disaster (i.e. there is a need to put some priority on reliable access from the main centres to areas prone to cyclone, flood or earthquake disaster) - disaster management impact

· Effect on the poor – a factor should be included to recognise the increased vulnerability of the poorer areas.

The relative weighting given to these different factors is sensitive. The range of values used for each factor should first be agreed, and then the weighting between these agreed. Factors considered not important should be given a value of 1.0 throughout.

4.4 INPUT INTO BMMS

The agreed factors and weightings should be set up on BMMS and tested using data for a pilot division. The results should then be checked to see if they are reasonable: represent a good prioritisation based on engineering judgement.

This will be discussed between the EE-BMPD and with the Field Division and if necessary modifications to the factors and weightings made. Once this is completed and agreed with the SE-PDC and approved by the ACE-BMW these factors and weightings shall be used throughout RHD as the basis of prioritising bridge maintenance and bridge replacement. In the case of Bridge Replacement under ADP, the priority lists will require a more detail review and economic assessment.

Based on this prioritisation the Annual RHD Bridge Maintenance and Rehabilitation Needs Report shall be prepared OP/PD/3.1.

4.5 NEEDS REPORT FINALISED

This prioritises the “long-list” (not grouped by division or linked to road priorities) of the annual bridge maintenance and rehabilitation needs report. This should not be used to prioritise maintenance verses replacement expenditure. This “long-list” is then split into two lists: replacement and repair lists. The top preliminary items on each list should be considered first.

These lists give a preliminary prioritisation, not the final basis for prioritising bridge replacement. Final prioritisation needs to consider bridges and roads together (See PD/3.1). After this, inclusion of bridge replacement in either the ADP or the periodic maintenance budgets will need a separate economic feasibility/appraisal study.
 
References :

None.
 
Procedure Flowchart :

The procedure flowchart for this procedure is detailed below -
 


 


 

 

For duties associated with each grade of personnel see

 

Updated on : 1/12/2003

Footer