01414352

Monograph

http://onlinepubs.trb.org...bs/nchrp/nchrp_rpt_154.pdf

A crucial question in the highway safety problem area is the level of skid resistance that should be available on highway pavements to provide for safe operation of motor vehicles. Dry pavements are usually quite adequate in this regard, but the skid resistance of wet pavements, which is one of the critical factors of traffic safety, is often of questionable adequacy for traffic conditions. The construction and maintenance of all pavements with wet skid-resistance properties comparable to those of dry pavements would not in most cases result in best use of available materials and funds because of the extremely high cost in relation to possible benefits. Realistic pavement skid-resistance requirements should be dictated by actual traffic needs at a particular site. Thus, the objective of the research described herein was to provide highway departments with methods for determining pavement skid-resistance requirements for any given set of roadway and traffic conditions. The Franklin Institute Research Laboratories' approach to development of procedures for determining skid-resistance requirements was based on the premise that measurable empirical relationships exist between the longitudinal and lateral accelerations resulting from vehicle maneuvers and pavement skid-resistance requirements. To evaluate this premise, it was first necessary to develop instrumentation to measure vehicle acceleration values at highway sites without influencing the driver behavior and vehicle operation. This was followed by skid studies using instrumented vehicles perfoming braking, cornering, and combination maneuvers on pavement surfaces with measured skid resistance and the correlation of the data with field-measured accelerations. The research was successful in that instrumentation for measuring acceleration values of vehicles at highway sites was developed.and field tested. Furthermore, procedures were developed and shown to be feasible for converting, in a relative manner, measured longitudinal accelerations at intersections braking sites to skid-resistance requirements. The report also describes a simplified Intersection Demand Model (1DM) for estimating skid-resistance requirements at intersections on the basis of speed, traffic count, and stopping distance data collected at the site. Additional field evaluation is necessary to determine more precisely the skidresistance requirements at intersections and to evaluate ability of the procedure to identify hazardous locations before they become high-accident sites. When it is not feasible to use either the Tapeswitch system or the Intersection Demand Model to determine pavement skid-resistance requirements, the information in Table 5 can provide general guidelines for minimum requirements. It must be recognized that these guidelines are very tentative because they are based on extremely limited field data (12 intersections in the eastern Pennsylvania and New Jersey area). The limited study of cornering maneuvers indicates that not enough is presently known about the relationship between lateral accelerations and pavement surface characteristics to permit development of procedures for determining skid-resistance requirements for highway curves. The problem is made particularly complex by the rather extreme, and yet undetermined, influence of vehicle tires. Other recent NCHRP publications concerned with the reduction of wet-pavement skidding accidents are NCHRP Synthesis 14, "Skid Resistance," and NCHRP Research Results Digest 61, "Wear-Resistant and Skid-Resistant Pavement Skid Tester correlation and Calibration Techniques."

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English

64p

1974

NCHRP Report

309023068

Digital/other

Acceleration (Mechanics); Braking; Intersections; Mathematical models; Rolling contact; Skid resistance; Surface course (Pavements)

Acceleration; Braking; Intersection; Modelling; Road surface properties; Skidding resistance; Vehicle pavement interaction

Highways; Pavements

ITRD, ATRI

Aug 24 2012 3:51AM