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Deficiencies, Needs

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

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Deficiencies, Needs

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  1. Deficiencies, Needs H. Scott Matthews January 22, 2003

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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?

  7. Approach to Defining Needs • From NCPWI 1986 - needs considers: • Consumer Demand • Recognition that demand changes • Consumer willingness to pay • Benefit-cost analysis

  8. 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

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

  10. 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

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

  12. 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

  13. Expected Service Life Estimates • Airport Buildings - 150 yrs • Runways - 50 yrs • Bridge Decks - 50 • Bridge Sub-/superstructure - 125 • Tunnels - 200 • Sports Complexes - 300 • Electricity/telephone lines - 400 • Any comments? Source: Hudson, Haas, Uddin

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

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