It varies from 20 m to a hundred m. Nearer intervals are expected if ground level may differ abruptly. The cross- sectional line need not be always be at suitable angles to the key line. This method is ideally suited to highway and railway projects. Radial Line Strategy Near Spacing: https://contoursurveyindhaka61504.blogofoto.com/63430169/the-best-side-of-contour-survey-in-bangladesh