According to Black’s findings, the estimated savings from the increased durability of various fly ash concrete life spans would be:

• $25 billion over 20 years ($1.2 billion per year average) if all concrete road­ways were designed with fly ash concrete materials to last 35 years, compared to the current national average of 20 to 25 years.

• $33.5 billion over 20 years ($1.7 billion per year) if all concrete roadway repair and reconstruction work used fly ash concrete with a 40-year life span.

• $51.5 billion over 20 years ($2.6 billion per year) if all concrete roadway repair and reconstruction work used fly ash concrete with a 50-year life span.

• $65.4 billion over 20 years ($3.2 billion per year) if all concrete roadway repair and reconstruction work used fly ash concrete with a 60-year life span.

The analysis utilized bid tab data from 48 states and Washington, D.C., collected and organized by Oman Systems, Inc., in Nash­ville, Tenn. The same data are used by the Federal Highway Administration (FHWA) to calculate the National Highway Construction Cost Index. It also used transportation construction market data from the U.S. Census Bureau, FHWA’s National Bridge Inventory and Highway Performance Monitoring System, and conducted extensive surveys and personal interviews with state transportation department officials and fly ash supply company executives to determine state market shares and penetrations.