23 C.F.R. § 1240 app E to Part 1240
A. To determine the savings to the Federal Government from reduced medical costs attributable to seat belt use, NHTSA will first estimate the impact of seat belt use on the number of fatalities and injuries, using methods described in the report "Estimating the Benefits from Increased Safety Belt Use." These methods establish a relationship between the effectiveness of seat belts, current use rates, and existing injury levels to determine the impact of increasing seat belt use on motor vehicle safety. Using these methods, NHTSA will estimate the fatalities prevented and the non-fatal injuries avoided by increased seat belt use.
B. In the 1996 report "The Economic Cost of Motor Vehicle Crashes, 1994," NHTSA measured both the medical costs and payment sources for motor vehicle crashes. NHTSA will adjust the national medical cost figures from this report to individual State income levels to reflect local cost levels. These per-case costs will be further adjusted for inflation, using the most recent annual average Consumer Price Index for medical care, and then multiplied by the injuries and fatalities prevented in each State to derive the total medical care savings from increased seat belt use. The Federal portion of these costs will be derived from the best available data found in the same cost report or in other sources, as they may become available.
23 C.F.R. § 1240 app E to Part 1240