Hydraulic Model Studies of Culvert Operation

Since 1951 the Division of Research has been engaged in a comprehensive study of highway drainage problems. This study has included special investigations of rainfall and runoff, drainage structures in use and the practices used in their design, culvert hydraulics, and other relevant investigations. To date, reports have been published concerning runoff and rainfall variables (1 and 2)* and the effects of barrel roughness upon culvert operation (3), together with the preparation of a drainage manual for the use of Highway Department engineers and consultants. The most recent special project, part of the over-all study, has dealt with the effects of inlet geometry upon the operation of culverts under entrance control. The procedures of this study have been somewhat unique in that they have made use of a scale model of a box culvert, set up in such a way that its operation could be closely observed and accurate readings could be made of water pressures, discharge quantities and the like. Although rather summarily reported on previously (4), the methods, underlying theories and results of this study are the subject of this report