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RHD Operational Procedure Bridge Management Wing
 
Bridge Design - Bridge Design Divisions
 
OP/BD/2.1 - In-house Bridge design
 
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.

This procedure is for the in-house design of bridges and other structures to be carried out by the Bridge Design Divisions.
 
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.

Design Engineer any engineer with structural engineering experience who in the opinion of the EE-BD in consultation with SE-Bridge Design Circle is sufficiently competent to carry out the particular design required.

Site Specific Data These must include soil survey, soils interpretative report, topographical survey, traffic flow motorised and non-motorised, environmental reports as required by OP/SE/3.1.

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 of 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. RHD Environmental standards in accordance with OP/SE/3.4.

BMW Standards Design Standards Manual, Current edition ASSHTO, 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 approves the Design.

Superintending Engineer Bridge Design Circle

1. Decides on whether the design is of a Complex Bridge or Structure.

2. Accept and sign off the Design and recommend approval to ACE-Bridge Management Wing.

Executive Engineer Bridge Design Divisions

1. Decide in consultation with SE-Bridge Design Circle the suitability of his staff to perform the duty of Design Engineer for a specific design,

2. Take on the role of Design Engineer if directed by the Superintending Engineer-Bridge Design Circle,

3. Ensure the quality of work undertaken by his staff and that Designs are properly prepared and collated for the checker,

4. Advise the Design Engineer,

5. Carry out checks on Designs prepared by his staff on structures less than 150 metre total span and not complex. After any necessary amendment sign off the Design as Checked.

6. Carry out checks as instructed by the Superintending Engineer-Bridge Design Circle and after any necessary amendment sign off the Design as Checked.

7. Ensure that all documents are properly stored and archived.

Design Engineer Responsible for the preparation of the Design and the Final Design Engineering Report.
 
Method :

At the outset of the design it is essential that the base data is sufficiently robust for a reliable design and construction leading to a bridge with a reasonable chance of achieving its design life. It is important that the Designer understands the site, flood levels, scour potential, vulnerability to river course change, potential construction restrictions and the affect on traffic during construction.

The design should take into account the need to preserve the bridge for the future and ensure if it is constructed over water that during periods of floodwater is directed under the bridge. Floodwater brings down much debris, designers should consider this when determining clearance and the ability of the bridge to accept later loads imposed during floods.

Earthquake design is also an important feature of design in Bangladesh. It is important that the Bridge Design Circle keeps up to date on current design and detailing (particularly reinforcement) related to earthquakes protection and incorporates them into their designs.

During the design the Designer shall be aware of the NCP Standard Technical Specification and where necessary develop Special Specification Clauses to ensure the structure is constructed as the designed.

The use of computer programmes and spreadsheets in design is given in OP/BD/1.2.

Any standard bridge designs shall be accompanied by full design calculations and only authorised standards approved by the Superintending Engineer Bridge Design Circle will be acceptable.

After Technical Approval to OP/BD/1.1 all documents shall be properly archived.
 
References :

See Paragraph 2 above.
 
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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