The Use and Efficiency of Some Gutter Inlet Grates

Résumé du livre

The development of an adequate and economical highway drainage system depends to a large degree upon the judicious use of gutters and gutter inlet grates. Gutters are usually provided adjacent to highway pavements to control excessive ponding of precipitation runoff, or to prevent erosion or saturation of the roadway shoulder. Another function of the highway gutter is to concentrate runoff so it may be intercepted and disposed of economically through the use of a sub-surface sewer system. The function of the gutter inlet grate is to intercept water flowing in the gutter, and to reject trash and large debris which might cause stoppage in the subsurface flow system. During the past few years considerable progress has been made toward the development of a truly efficient gutter inlet grate. This progress is the result of greater interest and attention on the part of the highway design engineer and an increased volume of theoretical and experimental studies on the subject. The purpose of this report is to present design relationships applicable to a series of typical inlet grates developed in a previous laboratory study. The program was conducted cooperatively with the Illinois Division of Highways, and the University of Illinois Engineering Experiment Station. The research program consisted primarily of an experimental determination of the interception characteristics of four Illinois Division of Highways standard inlet grates and frames. In addition to the experiment, a theoretical analysis of some of the factors which enter into the efficiency and use of gutter inlet grates was completed. The laboratory investigation required the construction of a full scale model 42 ft long. The model structure included four removable channel sections built to the exact cross-sectional dimensions of the four standard inlet grate frames used in the test program. The longitudinal slope of the model was variable so that the effect of various gutter slopes could be studied. The laboratory test program consisted of the determination of interception efficiency curves for the previous and present standard inlet grate design. The theoretical portion of the research program included the development of rating curves for three standard pavement sections. The experimental inlet grate efficiency data were re-arranged so they could be applied to any of the three pavement sections. The theoretical analysis also developed two examples to show how experimental data could be applied to a typical design problem.