Chapter 7 Roads: Geometric design and layout planning 7 GUIDELINES FOR HUMAN SETTLEMENT PLANNING AND DESIGN TABLE OF CONTENTS SCOPE . 1 INTRODUCTION. 1 Reference to planning . 1 Classification of the road and street system. 2 Measures of effectiveness (MOE) . 3 Traffic calming . 4 BASIC DESIGN PARAMETERS. 4 The design vehicle. 4 The design driver . 5 The road surface . 5 THE ELEMENTS OF DESIGN . 6 Design speed. 6 Ceiling speed . 6 Design hour . 6 SIGHT DISTANCE . 8 Stopping sight distance (SSD) . 8 Barrier sight distance (BSD) . 8 Decision sight distance (DSD) . 10 Passing sight distance (PSD) . 10 Intersection sight distance (ISD) . 10 HORIZONTAL ALIGNMENT . 13 Tangents . 14 Curvature and superelevation . 14 Superelevation runoff. 14 VERTICAL ALIGNMENT . 15 Curvature . 15 Gradients. 17 Climbing lanes . 18 CROSS-SECTION DESIGN . 19 i Roads: Geometric design and layout planning Chapter 7 GUIDELINES FOR HUMAN SETTLEMENT PLANNING AND DESIGN Lanes . 19 Shoulders . 21 Medians and outer separators . 22 Verges . 22 Sidewalks . 22 Slopes . 24 INTERSECTIONS . 24 Introduction . 24 Location of intersections. 25 The types of intersection control . .26 The form of intersections . 28 Intersection components . 29 Mini-roundabouts . 32 BIBLIOGRAPHY . 35 ii Chapter 7 Roads: Geometric design and layout planning GUIDELINES FOR HUMAN SETTLEMENT PLANNING AND DESIGN LIST OF TABLES Table 7.1 Comparison between classification systems . .3 Table 7.2 Dimensions of design vehicles (m) (after Wolhuter and Skutil 1990) . .4 Table 7.3 Minimum turning radii . .5 Table 7.4 Brake force coefficients . .6 Table 7.5 Recommended design and ceiling speed . .7 Table 7.6 Stopping sight distance on level roads . .8 Table 7.7 Barrier sight distance . .9 Table 7.8 Decision sight distance on level roads . .10 Table 7.9 Passing sight distance on level roads . .10 Table 7.10 Pedestrian sight distance . .13 Table 7.11 Maximum superelevation for various classes of road . .14 Table 7.12 Minimum radii for horizontal curves (m) . .14 Table 7.13 Rates and minimum lengths of superelevation runoff . .15 Table 7.14 Minimum values of.