Design Appreciation

One of the problems that Engineers face today is lack of appreciation of their work by other. They do not understand what designs involve and how changes affect the design, the behavior of say a structure, the amount of time that is required to carry out the works as a result of the change and finally the cost. We as Engineers should as soon as a change is proposed, estimate the time required to make the change, the additional cost and provide a break down of the effects if required.

What we need to think about when we agree to changes is whether we accept the liability for the change and the risks associated with it.

Recently I was designing a bridge in the Middle East, where American Code AASHTO was used. The client proposed a change in the carriageway width by 2.3 m (by removing the verges on each side of the carriageway, keeping the overall width of the bridge the same) and stated “Can you please re-run the loadings from experience this should be pretty quick and simple”

. Below were the items that I communicated to the client:

• The new layout changed the number of notional lanes resulting in re-doing the deck loading.

• Load combination need to be re-run

• Result need to be extracted

• Design of all element, Prestressed beams, deck, diaphragms, edge cantilever, abutments, pilecaps piles and bearing schedule need to be checked/amended.

• Load on the abutments will change, the design of the abutments need to be checked

• Load on the foundations will change, the foundations have to be re-analysed, this may result in increasing the pile length, or increase in the pile no. and layout.

• The programme of works will need to be amended as the original deadline can not bet met

• Management and communications cost as a results of the change.

• The cost associated with the change will be calculated if necessary but it is a good proportion of the design cost.

The above resulted the design to be carried out without the change.

If I had alternatively carried out the design with the change without communicating the issued listed above it would have resulted in carrying out a lot of work and not getting paid for.

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