The need to repair a failing infrastructure is evident by an assessment of the American Society of Civil Engineers. The current infrastructure in the USA was rated a "D" with extensive engineering maintenance required just to bring the existing infrastructure up to legal and professional codes and standards.
The case for upgrading infrastructure is made due to more storm activity along the coastline of the United States, the continuing corrosive elements in nature, a growing population and an economy of nearly fifteen trillion dollars. There are 3.8 million square miles in the United States.
In 1960, the population was one hundred eighty million which translates to 47 people per square mile. Today, there are three hundred ten million people or 81 people per square mile. In 2050, the population will be five hundred million people or 132 people per square mile. These trends show clearly that growing
numbers of people will be utilizing the same infrastructure under more severe weather trends.
Repair of the infrastructure is designed to anticipate the continuing impact of nature on the existing infrastructure. Corrosion of metals on bridges, tunnels and rails is the result of factors like temperature, oxidation and acidity. In fact, acidity and oxidation frequently happen concurrently. The rate of corrosion is often determined by electrolysis which results in the pitting or roughening of a metallic surface in places like rails and bridges.
Concrete in roads, tunnels, nuclear power plants and dams can withstand compression forces but deteriorates with tension. The performance in tension can be improved with casting the concrete with rods or mesh so that the steel absorbs the tension load.
The tremendous forces of tornadoes are circular in geometric appearance and the forces are non-linear like in the Mohr circle. Earthquake engineering deals with the reinforcement of materials to withstand the various primary and secondary waves which accompany these natural disasters.
Infrastructure enhancements and the building of brand new facilities can be paid for in a number of ways. The traditional payment mechanisms are with public bonds, federal grants, toll roads and taxes on local governments.
The resources for capital projects funds usually come from general obligation bonds but resources can come from general tax revenues, federal grants or shared revenues from other governmental sources. Special assessment bonds are paid thru special levies against specific properties receiving benefits from special assessment improvements. Revenue bonds are payable from the earnings of a governmental enterprise and are accounted for in an appropriate enterprise fund. General obligation bonds are supported by the full faith and credit of the governmental unit itself.