The Local Rural Road System: Alternative Investment Strategies, HR-242, 1989

A benefit-cost analysis was used to examine the effects of alternative investment strategies on the local rural road system. The study first estimated the change in costs to the traveling public of various investment strategies, then compared the change for each investment strategy to the cost of implementing that strategy on the county rural road system. The basic purpose of this study was to develop guidelines for local supervisors and engineers in evaluating investment or disinvestment proposals, and to provide information to state legislatures in developing local rural road and bridge policies. Three case study areas of 100 sq mi each were selected in Iowa. A questionnaire was used to collect data from farm and non-farm residents in the study areas. Data were obtained on the number of 1982 trips by origin, destination, and type of vehicle.

Development of Non-Petroleum Based Binders for Use in Flexible Pavements, TR-594, 2010

Most bituminous adhesives or binders that are used for pavement materials are derived primarily from fossil fuels. With petroleum oil reserves becoming depleted and the drive to establish a bio-based economy, there is a push to produce binders from alternative sources, particularly from biorenewable resources. However, until now, no research has studied the applicability of utilizing bio-oils as a bitumen replacement (100% replacement) in the pavement industry. The main objective of this research was to test various properties of bio-oils in order to determine the applicability of using bio-oils as binders in the pavement industry. The overall conclusions about the applicability of using bio-oils as bio-binders in the pavement industry can be summarized as follows: 1. Bio-oils cannot be used as bio-binders/pavement materials without any heat pre-treatment/upgrading procedure. 2. Current testing standards and specifications, especially Superpave procedures, should be modified to comply with the properties of bio-binders. 3. The temperature range of the viscous behavior for bio-oils may be lower than that of bitumen binders by about 30°–40° C. 4. The rheological properties of the unmodified bio-binders vary in comparison to bitumen binders, but the rheological properties of these modified bio-binders change significantly upon adding polymer modifiers. 5. The high-temperature performance grade for the developed bio-binders may not vary significantly from that of the bitumen binders, but the low-temperature performance grade may vary significantly