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RHD Operational Procedure Bridge Management Wing
 
Bridge Design - Bridge Design Divisions
 
OP/BD/2.2 - Bridge Design (external)
 
Purpose and Scope :

Bridges are the most expensive individual assets on a road network. Bridges must be designed to last many years with a minimum of maintenance. Incorrect design may lead to inappropriate structures, high maintenance cost and shorter than planned life. The following sets out the procedure to minimise error or bad judgement that may result in poor bridge designs being constructed.

The role of the Bridge Design Circle when an outside party, normally a consultant, carries out the design is to ensure that the best structural form is selected for the purpose, the designs are robust and fully comply with RHD Standards. The work will normally be carried out under a Project Director with whom the Bridge Design Circle must assist as technical experts.

This procedure sets out the role of the Bridge Design Circle when designs are prepared externally; normally by consultants both on GOB and Foreign aided projects.
 
Definitions :

Final Engineering Design Report The report includes:

1. The design brief,

2. Reference documents including surveys, topographical, soils and hydrological and hydrographical.

3. Any necessary assumptions during the design.

4. The design calculations,

5. Proposed maintenance requirements.

Designs are Final Engineering Report, detail drawings, and additional clause to the Technical Specification (Volume 3 of NCP) to be included in the Special Technical Specification in the Contract Documents. All designs drawings and specification to be completed to a standard that they can be constructed without modification.

Project Director (PD) for the purposes of this procedure is the person in charge of the project.(whether formally appointed as the Project Director or not).

Site Specific Data These must include soil survey, soils interpretative report, topographical survey, traffic flow motorised and non-motorised, Environmental Impact Assessment OP/SE/3.1(required if new build or rehabilitation).

In addition these must include as appropriate, condition survey of any adjacent structure, hydrological survey, hydrographical survey, Resettlement Plan.

(If any of this information is not immediately available arrangements must be made to obtain the surveys/reports before agreement in principle is given).

Special Requirements These are the requirements of Local Authorities, Bangladesh Railway Authority, Bangladesh Inland Water Transport Authority, Civil Aviation Authority Utility Companies, any other concerned statutory authority or body that may be affected by the proposed works.

BMW Standards Bridge Design Standards, Bridge Designers Handbook and its Supplement, Bangladesh Seismic Data, NCP Volume 3 Technical Specification, Standard Contract Drawings, Standard Design Drawings Approved by Bridge Management Wing, Approved computer software.

Constructability The ability to construct the works within the site restraints, depth of excavation next to other structures or existing roads, includes provision of workspace, dealing with existing traffic during construction, safety of the public and the work force.
 
Responsibility :

Additional Chief Engineer Bridge Management Wing accept the Design on behalf of RHD.

Project Director Direct the project and manage the consultant.

Superintending Engineer Design Circle

1. Technical advisor of PD.

2. Review base data and comment on designs from outside and when satisfied recommend acceptance of designs,

3. Undertake duties described in OP/BD/1.1.

Executive Engineer - Bridge Design Divisions

1. Assist SE BD as necessary.

2. At the end of the commission ensure that all documents are properly stored and archived.
 
Method :

4.1 PREPARATION OF TOR FOR CONSULTANTS

Prior to the preparation of the Terms of Reference (TOR) for the consultancy services to design a bridge the PD reviews and agrees with the SE Bridge Design Circle the extent of any necessary survey data needed for a robust design. The PD then includes this in the Terms of Reference or arranges for other means of collection of data. Designs should be carried out to RHD Bridge Standards. The PD in preparation of the TOR should include any requirements for services necessary to comply with BMW procedures particularly compliance with The Technical Approval procedure OP/BD/1.1. The PD should where Technical Approval requires a 3rd Party checker procure the services of an appropriate consultant to undertake this check.

4.2 SITE VISIT REVIEWS BY SE BRIDGE DESIGN CIRCLE

It is suggested that the SE-Bridge Design Circle, or, if he is not able, a nominee should view the site and record the site visit with a note for the file with, if possible some photographs. The purpose of the visit is to form a first hand opinion on constructability, dealing with traffic during construction and aesthetics. The SE-Bridge Design Circle may wish to make a number of visits to site as the design progresses enabling informed, site-specific advice to the PD.

4.3 ACCEPTANCE OF BASE INFORMATION FOR DESIGN

In the design preparation the consultant should present the base information on which he proposes to carry out the design. Should the consultant request additional surveys, over and above that already available he must justify to the PD and his advisor SE-Bridge design Circle. The PD should then approve or disapprove and take or instruct any necessary action.

4.4 BRIDGE TYPE OPTIONS

On completion of preliminary bridge type options the consultant shall report and present each option comparing, aesthetic form, how any Special requirements will be met, constructability, method of dealing with traffic during construction, construction costs, whole life costing and any relevant information necessary to choose an option. In his presentation the consultant should also highlight any risks associated with the design. The PD and SE-Bridge Design Circle will review the report and attend the presentation. Once satisfied with the report and presentation the PD and SE-Bridge Design Circle shall decide which option should be taken forward to detail design.

4.5 APPROVAL OF BRIDGE TYPE AND ACCEPTANCE OF DESIGN

Following completion of the design and Technical Approval Procedures the SE-Bridge Design Circle recommends APPROVAL of the type of the structure and recommends ACCEPTANCE of the design to ACE-Bridge Management Wing. This APROVAL and ACCEPTANCE is submitted to the PD.

4.6 ARCHIVING

When designs are complete all design documents, including the Final Engineering Design Report, drawings (both hard copy and on compact disc) etc. must be archived by the Bridge design Circle for possible future reference.
 
References :

OP/BD/1.1 Technical Approval

OP/SE/3.2 EIA Report
 
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

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