Motorcycle crash fatalities in the United States have been increasing since 1997, when the total number of fatalities reached a record low. Motorcycle training programs were enacted before this rise, and many studies have aimed to show their effectiveness. The objective of this study is to review and synthesize the results of existing research on the effectiveness of motorcycle education courses and different licensing procedures. The effectiveness of programs is examined through the effect training has on accident rates, violation rates, and personal protective equipment use found through past research. Research to date has not consistently supported the notion that training is either effective or ineffective. Some studies have demonstrated that accident and traffic violation rates are lower for trained riders than for untrained riders, whereas others have demonstrated that they are higher for trained riders. Training increases the use of personal protective equipment among motorcyclists. Motorcycle licensing procedures have been shown to have different effects on accident rates. Lower accident rates have been observed in areas with stricter regulations for obtaining a license. The studies vary greatly in both the methods used for comparison and the rigor of their evaluation methodology. No standards for evaluation exist. The findings of these previous studies may be more a reflection of the methods used to evaluate motorcycle training than the effectiveness of training itself.
In the early 1980s heavy-duty pavements in Pennsylvania showed evidence of excessive rutting. As a consequence, the Pennsylvania Department of Transportation adopted several changes in its materials specifications and mixture design procedures. In addition, a number of modified binders were evaluated in an experimental test road that was constructed in 1989 in Clearfield County on Interstate 80. The construction was a 175-mm thick asphalt concrete overlay over an existing portland cement concrete pavement. Although the construction predated Superpave, original samples of the asphalt binder and loose asphalt mix were retained and were characterized using Superpave test methods. Field performance evaluations were performed immediately after construction and in subsequent years, giving a record of rutting, cracking, raveling, and overall visual performance. Overall, the mixtures have performed well during their 9 years of service. However, differences in the performance of the mixtures with the different binders are evident. These differences are related to the properties of the binder and the properties of the mixture as measured with the Superpave mixture and binder tests.
Developing countries are striving for the development of infrastructure facilities including transportation systems. India has a national highway with a length over 52,000 km. A further 14,000 km length of express highway is currently being built under the golden quadrangle and NorthSouth and East -West corridor projects. These projects have large scope for adopting superpave technology.The strategic highway research program (SHRP) conducted a $ 50 million research effort from 1987 to 1993 to develop a new concept for the design of bituminous mixes referred to as superior performing asphalt pavements (superpave). Superpave mixes have been widely used by the developed countries for the last few years but the developing countries are still working with the conventional mixes i.e. marshall mixes. Flexible pavements, with bituminous surfacing as a wearing course, are widely used in India. The objective of this study was to compare the design of asphaltic concrete by the superpave and marshall methods of mix design. A detailed laboratory study was carried out using aggregate from the Delhi region and bitumen from the Mathura refinery. From the analysis of design of asphaltic concrete, it was observed that superpave mixes fulfill all the criteria for easy and good construction at lesser binder content than the marshall mixes. Apart from superpave mix design, the effect of angle of gyration, number of gyrations on mix properties like density, stability, indirect tensile strength were also determined. Results revealed that percentage theoretical maximum density increases with the increase in number of gyrations. At any level of gyration, theoretical maximum density percentage increases with increase in gyratory angle. Further, it was observed that indirect tensile strength decreases with increase in angle of gyrations.Comparing both the design methods, it was observed that marshall compactor is unable to answer the rutting resistance of the designed mixture. The marshall compaction effort in the field laboratory corresponded to an air void content of slightly less than six percent, and the mixture appeared to stabilize under traffic at an air void content between three and four percent. In contrast, superpave gyratory compactor is capable of achieving air void contents much lower than achieved by mechanical marshall hammer compaction. This prevents additional compaction under traffic, which could result in rutting in the wheel paths. Hence, marshall mix design should be replaced by superpave mix design for Indian national highways/express highways, which compact the specimens in the same manner as compacted under actual pavement climate and loading conditions.
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