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A Marketing Approach to Bridge Longevity: 

A Marketing Approach to Bridge Longevity All about being specifically wrong … while being generally right Presented by: Heinrich O. Bonstedt Executive Director Prestressed Concrete Association of Pennsylvania

The Engineering Approach: 

The Engineering Approach Examines Each Specific Criteria Therefore, Every Bridge is Different in a Thousand Ways Design Construction Climate Weather Traffic Etc, etc

The Engineering Goal: 

The Engineering Goal To be Specifically Right

The Marketing Approach: 

The Marketing Approach Examines Only Basic Criteria To Draw Conclusions To Make Decisions To Create Forecasts

The Marketing Goal: 

The Marketing Goal To be generally right (While often being specifically wrong)

Data Analysis for Insights: 

Data Analysis for Insights

Bridges are Important to Us: 

Bridges are Important to Us They even directly support education!

But Bridges Don’t Last Forever: 

But Bridges Don’t Last Forever

Data Source: 

Data Source The National Bridge Inventory December 2000 Prepared according to a Standard Recording and Coding Guide that covers over 115 items “By having a complete and thorough inventory, an accurate report can be made to Congress” and it provides the data necessary to “produce Defense Bridge and Federal Emergency Management Agency (FEMA) reports.”

Evaluation Objectives: 

Evaluation Objectives Determine deficiency rates for bridges Evaluate deficiency trends Compare bridge material alternatives Establish a basis for projections of service life expectancy

Limitations of our NBI Analysis: 

Limitations of our NBI Analysis A continuation of past practices was assumed to continue into the future In view of the scope of the sample factors such as location, uniformity of rating were assumed to hold true over the period studied

Constraints Applied to Data: 

Constraints Applied to Data Constructed or reconstructed after 1950 No railroad bridges or buildings and plazas No Culverts Distance between back-walls of abutments >20 feet Consider only structural deficiencies from Appraisal Ratings (2 or less) Condition Ratings (4 or less) Deck Super-structure Sub-structure

Elimination of Coding Errors: 

Elimination of Coding Errors Blank or improperly coded records in the following fields were discarded: Inventory route Type of service Structure length Bridge width Year built and/or reconstructed Structure use Materials used Condition rating

Sample for the Trend Analysis: 

Sample for the Trend Analysis 683,861 structures in the National Bridge Inventory 459,286 bridges remained for analysis 369,985 of which have been built or reconstructed since 1950

Deficiencies Reported (all thru 1998): 

Deficiencies Reported (all thru 1998)

Deficiencies Reported (1950 thru 1998): 

Deficiencies Reported (1950 thru 1998)

Plotting Limitation: 

Plotting Limitation When plotting ratios (deficiency rates), those based on fewer than 275 units per year were omitted from plotting – but not from later computations.

Sources of Deficiencies: 

Sources of Deficiencies Super-structure condition Sub-structure condition Deck condition Appraisal Rating

Deficiencies by Road System: 

Deficiencies by Road System Interstate Highways US Numbered Routes State Highways County Roads Other Roads All Highways, Routes and Roads

Trend Evaluation: 

Trend Evaluation Statistical analysis of deficiencies on the identified roads systems indicates a parabolic trend, following the general algorithm: Y = a + bx + cx2 where, Y = the percentage of bridges rated deficient x = the number of years since the bridge was constructed and/or reconstructed

Conclusions: 

Conclusions While engineering standards and specifications aim to create solutions of equal performance across all materials, actual results indicate that concrete bridges outperform their competitive materials

Conclusions - continued: 

Conclusions - continued Individual service life expectancy projections are:

Conclusions - continued: 

Conclusions - continued The most reliable, simply because there is more data, would be a projection for all road systems combined:

Conclusions - continued: 

Conclusions - continued To account for these differences in service life expectancy, “first costs” of a bridge would have to factored by the following to reflect performance parity: Prestressed Concrete 1.00 Reinforced Concrete 1.01 Structural Steel 1.26 Timber 1.44

Thank you for your attention!: 

Thank you for your attention! Questions?