Road Design
Question 1
In the pre-construction stage what information would you source to help you ‘best fit’ a design to the environment?
The information that may be sourced during the pre-construction stage could include: • Terrain details • Survey data, existing plans & maps (including topographical & geological maps) • Cadastral boundaries • Location of existing structures • Ownership information • Details of existing road alignments, are there any concerns with the current alignment? Is there a history of accidents on the existing road alignment? • Underground and overhead services (electrical, water, sewerage & gas) • Important environmental features • Traffic volumes & composition • Class of road • The possibility of stage construction • Budget • Environmental impact assessment • Hydrological reports
The information gathered must include a corridor of enough width to allow the designer scope to vary the position of the center line of the road if necessary. It may also be necessary for the designer to walk over the proposed route, to gauge the terrain and the environment and to assist in predicting in any possible problems that may arise.
Question 2
What design factors will influence the road location and standard? Nominate the dimensions that you would expect for all of the individual road elements and why. Nominate the horizontal and vertical geometry limits that you would expect to incorporate and explain why.
The principle factors that influence the choice of a design standard for a road are as follows: • Traffic volume • Traffic composition • Terrain • Environment • Cost • Safety • Stage construction • Class of road • Appearance
The vertical alignment of the road will include a series of straight sections joined by a series of curves, being parabolic in shape. A convex (crest) curve will be present at point B and a concave
In the pre-construction stage what information would you source to help you ‘best fit’ a design to the environment?
The information that may be sourced during the pre-construction stage could include: • Terrain details • Survey data, existing plans & maps (including topographical & geological maps) • Cadastral boundaries • Location of existing structures • Ownership information • Details of existing road alignments, are there any concerns with the current alignment? Is there a history of accidents on the existing road alignment? • Underground and overhead services (electrical, water, sewerage & gas) • Important environmental features • Traffic volumes & composition • Class of road • The possibility of stage construction • Budget • Environmental impact assessment • Hydrological reports
The information gathered must include a corridor of enough width to allow the designer scope to vary the position of the center line of the road if necessary. It may also be necessary for the designer to walk over the proposed route, to gauge the terrain and the environment and to assist in predicting in any possible problems that may arise.
Question 2
What design factors will influence the road location and standard? Nominate the dimensions that you would expect for all of the individual road elements and why. Nominate the horizontal and vertical geometry limits that you would expect to incorporate and explain why.
The principle factors that influence the choice of a design standard for a road are as follows: • Traffic volume • Traffic composition • Terrain • Environment • Cost • Safety • Stage construction • Class of road • Appearance
The vertical alignment of the road will include a series of straight sections joined by a series of curves, being parabolic in shape. A convex (crest) curve will be present at point B and a concave