Deficiencies, Needs H. Scott Matthews January 22, 2003

Recap of Last Lecture  Grant (95) summarized condition ratings of many parts of built infrastructure  Data seemed to indicate big problems, but did not necessarily give us information on the extent of problems  There were some missing pieces

Deficiency Ratings - Bridges  Dunker & Rabbat (Dunker 95)  Same general idea as Grant, but with more detail and data refs (e.g., NBI)  NBI used as information source to U.S. Congress to justify spending  States can use own system, but must report in form usable by NBI  Ratings subjective, but follow a given and preset scale  Shows coding guide and inspection rules

Areas of concern  Structural Deficiency (SD) - has been restricted to light loads, or is closed, or requires immediate work to stay open  Functionally obsolete (FO) - one of several design parameters no longer meets usual criteria for system

Geographical Differences  Unlike Grant, Dunker separates bridge problems into ownership  See spread of SD and FO across national -> locally maintained bridges  And by bridge material (e.g. concrete)  Let’s look at NBI website

Needs Assessment  Concept of ‘need’ used casually  Can refer to both ‘need’ for repair as well as ‘need’ for new capacity  It is difficult to judge how much infrastructure a region or a society ‘needs’ and how ‘need’ is measured  Economic viability? Growth?  What is a better approach?

Approach to Defining Needs  From NCPWI needs considers:  Consumer Demand  Recognition that demand changes  Consumer willingness to pay  Benefit-cost analysis

Other Issues on Needs  Instead of focusing on conditions, establish future investment priorities  Instead of simply finding cost to repair, consider cost of alternatives with same effect  Consider infrastructure ‘output’ as measure instead of condition  Funding needs to match area of influence, e.g. federal money for federal interests

More Issues  Needs assessments should distinguish:  Safety or structural defects  Capacity shortages  Upgrading to new standards  Current and future demands

Life Cycle Cost Analysis (LCCA)  A ‘life cycle’ is the entire length of time from design, planning, construction, operation, maintenance, and decommissioning/demolition  It is important to understand the cost implications of design decisions across the life cycle  Also important to understand where in the life cycle that total costs occur

Life Cycle Cost Influences Decreasing Influence Increasing Expenditure 100% 50 % 0%0% Planning Design Construction Maintenance Disposal Time Cum. Cost Level of Influence

Related Topic: Service Life  Physical service life is the length of time which a piece of infrastructure is able to be kept in useful service  Depends on all life cycle phases  Can be extended from original design due to rehabilitation or preventive maintenance

Expected Service Life Estimates  Airport Buildings yrs  Runways - 50 yrs  Bridge Decks - 50  Bridge Sub-/superstructure  Tunnels  Sports Complexes  Electricity/telephone lines  Any comments? Source: Hudson, Haas, Uddin

Homework 1 - due next Wed  Any questions?  Next class: design-service life and obsolescence  Read Lemer (1996)