The SAE Recommended Practice 51802, Brake Block Effectiveness Rating [I], has the purpose of establishing a uniform procedure for determination and classification of brake effectiveness for commercial vehicle brakes. The practice provides a means to characterize the friction properties of truck brake lining materials in a representative S-cam brake. However, the test has been found to exhibit an unacceptably large range of variability in the implied friction coefficient for the lining. It has been postulated that some of the: variability arises from factors within the brakes that are used for the test-specifically, dimensional tolerances, and possibly friction in the moving parts. A computer model of an S-.cam brake was developed under this work to help examine various brake parameter sensitivi~ties. The model calculates brake torque for a specified set of geometry, friction properties, arid constant input air chamber force. It assumes that the brake is in a state of equilibrium defined by equalized wear rates on the leading and trailing shoe linings. The parameter!sensitivity findings indicate that a potentially significant source of torque variability is related to possible offsets between the drum turning axis and the spiderlshoe assembly centerline. Other

Administration. Credit-based congestion pricing (CBCP) is a novel strategy which seeks to overcome the negative equity impacts of congestion pricing (CP) by allocating monthly budgets to eligible travelers to spend on congestion tolls. Previous CBCP studies have surveyed public opinion and examined the traffic and travel-welfare impacts of an Austin, Texas application. This work develops the policy further, examining expert opinions, predicting traffic impacts, estimating air-quality changes, and predicting system costs. 17. Key Words pricing options, congestion tolls, Credit-based congestion pricing (CBCP), congestion pricing (CP) 18. Distribution Statement

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IS. Supplementary Notes

This document is available to the public through the National Technical Information Service, Springfield, VA 22161This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. TECHNICAL REPORT STANDARD TITLE PAC

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Quantitative and qualitative

This research aims to advance the state of the art in daily activity-travel modeling. It represents one of the first attempts to comprehensively model the activity-travel patterns of workers as well as non-workers in a household. The activity-travel system will take as input various land-use, socio-demographic, activity system, and transportation level-of-service attributes. It will provide as output the complete daily activity-travel patterns for each individual in the household. 17. Key Words Travel demand modeling

ABSTRACT These two curriculum demonstration projects on bilingual readiness in the earliest school years contain many similarities. Both were formed on the thesis that young children can and will learn a second language readily and that the urban classroom mixture of Spanish-speaking, Englih-speakingt gand Nero-dialect speaking children can be capitalized on to further bilingual and intercultural development of all groups. The objectives of the projects were to (1) foster bilingual development in children at a prime readiness age (4 to 8), (2) promote positive attitudes among native English speaker toward the language and culture of other groups, and (3) enhance the self-concept and pride n heritage of chil Bilingualspeaking Spanishnwhile teachivthem Engliish. In, both studies a Specialist met with classes rf Kindergarten and 1st grade children 15 to 20 minutes per day. Both English and Spanish were used during these periods. Much of curriculum activity involved listening to stories,