Based On The Custom Entity Technologies Of Highway Embankment Cross-sectional Design

The cross section design is an important part of the road design. It concerns lots of data. The design process done by hand is complex and the designers are liable to make mistakes in the process. The application of the CAD technology can solve the problem and play a very important role in improving the design quality and efficiency.This article has done a thorough and careful research on the calculation of superelevations and widening values of the cross section, the principles and methods of cross section automatic design, the technology of custom entity and interactive design of graphics and data. The chief research contents and achievements are summarized as follows:(1)A method is presented to calculate superelevations and widening values of characteristic point on an arbitrary cross section by the principle of segmentation. First of all, the superelevation and widening characteristic sections are found out and then these characteristic sections are used to divide the road into a number of segments which properties are simple, in each segment the road cross-slope of any part of cross sections changes linearly. In this way the road cross-slope of any cross section can be calculated by using interpolation method. At the same time, the function of the interactive modification of superelevation and widening segments' data based on the technology of custom entity is implemented and it enhances the practicality of the system.(2)Based on the technology of custom entity, the data of road surface templates, side slope templates and ditch templates can be inputted in an interactive way that graphics and data is linked, this method is of convenience, simplicity and intuition.(3)On the basis of comprehensive analysis of the characteristics of road cross section, according to the roadbed templates, the side slope templates and the ditch templates, the automatic cross-sectional design of the whole and separate cross sections of the road is implemented, and the cross-sectional design of the part separate roadbeds is completed by merging the relational roadbeds.(4)The database for saving the parameters of retaining wall is built. The parameters of retaining wall can be read from the database by means of operating the database through ADO technology. The various roadbed design tables can be created by Operating Excel through ActiveX technology.(5)Based on the technology of custom entity, a special entity for cross section is defined. The working principle and the realization of cross section interactive design and modification is discussed and then a cross section interactive design and modification module is developed.