chapter  1
14 Pages

What a Geometric Designer Needs to Know

Geometric design is defined as the design of the visible elements of the road. In effect, the geometric designer is the architect of the road. As such, geometric design includes a fair measure of art amongst the science. It follows that designers should be sensitive to the perceptions of the people who are using the road, whether they are drivers or passengers in a vehicle or outside vehicles. If they are outside the confines of a vehicle, people may be pedestrians heading for a specific destination, relaxing at pavement cafes or perhaps window shopping. They may also be members of the community through which the road passes and this could include children playing in the street. Whatever the reason for their being either in the road reserve or adjacent to it, they have the fullest right to be there. To develop a design that will balance all these conflicting needs, it is necessary for the designer to go beyond

CONTENTS

1.1 Introduction ..................................................................................... 3 1.2 How to use this book ....................................................................... 4 1.3 Safety and geometric standards ........................................................ 5 1.4 International nomenclature .............................................................. 5 1.5 The broader approach to design ....................................................... 6

1.5.1 Human factors ....................................................................... 6 1.5.2 Design consistency ................................................................. 7 1.5.3 Context-sensitive design ......................................................... 8 1.5.4 The design domain................................................................. 8 1.5.5 The design team ..................................................................... 8

1.6 Supporting disciplines ....................................................................... 9 1.6.1 Introduction ........................................................................... 9 1.6.2 Systems analysis ..................................................................... 9 1.6.3 Project analysis .................................................................... 10 1.6.4 Transportation planning ...................................................... 11 1.6.5 Capacity analysis ................................................................. 11 1.6.6 Traffic flow theory ............................................................... 11 1.6.7 Environmental issues ........................................................... 12 1.6.8 Hydrology and hydraulics .................................................... 12 1.6.9 Survey .................................................................................. 12

1.7 Urban versus rural geometry .......................................................... 13 1.8 Conclusion ...................................................................................... 15

merely seeking to ensure that vehicles can travel between origin and destination with the minimum of impedance to their passage.