A rational and practical method for determining highway capacities is essential for sound economic and functional design and utilization of the highway transportation system. The ability to accommodate vehicular traffic is a primary consideration in the planning, design, and operation of streets and highways. Highway capacity is a measure of the effectiveness of various highways in accommodating traffic, and its application requires both a general knowledge of traffic behaviour and specific knowledge of traffic volumes that can be accommodated under a variety of roadway configurations and operating conditions. Capacity is defined as the maximum number of vehicles per unit of time that can be handled by a particular roadway component under the prevailing conditions. This manual is designed to provide a condensed and authoritative source of the present empirical and theoretical information on highway capacity. By providing a standard set of terminology and methods of measurement and analysis, the manual will aid in the study and evaluation of existing facilities. Description of traffic behaviour found in field studies is given to aid in predicting the capacity and level of service in proposed improvements. The manual does not provide rigid standards for capacity measurements, but provides a guide in lieu of more detailed information. The principal characteristics of traffic operation relating to capacity are discussed for the various highway elements. Specifically discussed are at- grade intersections, weaving, ramps, and bus transit. Levels of service and service volumes of freeways, other expressways, streets and highways without access control are analysed. Field studies and research results are correlated with present highway design practice and rational procedures are developed for analysing the capacity of existing or proposed facilities.
Samenvatting