Obsolescence & Service Life H. Scott Matthews January 27, 2003

Recap of Last Lecture  Built infrastructure deficiencies lead to ‘needs’  Needs studies should estimate NEEDS not WANTS  Costs of infrastructure need to be managed and planned over life cycle  Infrastructure generally built to last longer than it would actually be useful

Obsolescence  Condition of being antiquated, old- fashioned, or out-of-date  No longer meets current needs or expectation levels  Aging, technology, standard change  2-yr old computers good example  Inability to meet changing performance requirements

Obsolescence & Service Life  “Always remember that someone, somewhere is making a product that will make your product obsolete”  -Georges Doriot  “Planned obsolescence” by Vince Packard’s The Waste Makers  Practice of deliberately designing products to last for a shorter period of time  Systemically doing this leads to inferior products

What Causes It?  Technological change  Regulatory change  SDWA forced upgrades  Economic / social changes  Value / behavior changes

Economics  Performance = P(S,D,t)  S = Supply of infras. Services = S(X)  X = set of functional characteristics  Planners want adequate X, S over time  ‘Satisficing’ (Simon 57)  D = demand for these services

“Failure”  Failure as not meeting expectations  Happens when P(t) < P F  Need to maintain performance level  Expectations increase over time P PFPF TDTD

Service vs. Physical Lives  Physical Lives: time it takes for infrastructure to wear out/fail  Predicting this may be irrelevant  Service life: time actually used  In general these 2 are different  Power plants become obsolete because of technology/policy changes  In some cases, tax code drives expectations

Connections  “Design service life” only meaningful if defined in terms of obsolescence  Assumptions about lifetime will likely change over time  Infrastructure seldom abandoned before replacement in place  Expectations will increase  Need to consider expectations and deterioration functions

Rates of Change  Information economy is making older transport modes obsolete  E.g., ground -> air shipping  How long should infrastructure last?  Physical or service?  “How long do you want to use it?”  Where will it go when we’re done?  What could we do with Roman roads now?

Strategies to Mitigate  Plan and design for flexibility  Build to assure optimum performance level is achieved  Monitor change to defer obsolescence  Refurbish and retrofit early