Life-Cycle Cost Analysis For Bridges
James E. Roberts, P.E.; Honarary Member ACI; Honorary Member ASCE; President, American Segmental Bridge Institute
Much has been written about life-cycle cost analysis for bridges but little work has been done in the actual application of life-cycle costs in the evaluation of bridge alternatives.
As a beginning, it is important to understand that life-cycle costs are controlled by many factors such as design details, construction quality control, maintenance and the types of materials utilized. Good bridge performance begins with good design, giving attention to avoid those details that have caused past problems. This is one of the best forms of preventive maintenance and the key to longer bridge life.
The second major factor in long-life performance is strict quality control and quality assurance by the owner during construction. It does not matter how well the plans and details are prepared if the construction is not carried out to the highest standard.
The third major factor in assuring long life for bridges is good maintenance. Timely and thorough maintenance inspections by qualified engineers or engineer supervised bridge inspectors followed by written reports which are analyzed and acted upon in a timely manner are a key to a good long-term maintenance program.
When all factors are considered, the use of segmental concrete bridges makes sense because they are under compression due to post-tensioning, generally in both longitudinal and transverse directions. This significantly reduces the maintenance problems caused in non-prestressed concrete by cracking and water penetration.
Editor’s note: the above excerpts from Jim Roberts’ summer 1999 newsletter editorial are reprinted as a remembrance of Jim’s very significant contributions to ASBI and the segmental concrete bridge industry. Jim had a remarkable 50 year career with Caltrans, where he become internationally recognized in reference to seismic safety of bridges. He will be greatly missed.