# CIV4ID Infrastructure Design- computation of horizontal alignment

Alignment design

a) Develop the alignment(s) for the bypass route(s) having regard to the co-ordination of horizontal and vertical alignments and the technical, environmental and social design constraints. This will involve the selection and computation of horizontal alignment geometry and vertical curve design making proper provision for sight distance and requires consideration of curve radius, super-elevation development, transition length, vertical curve length and geometry, grades etc.

b) Set chainage points at 20m intervals commencing at the take-off point. Note that for this exercise, the design line shall be the centreline.

c) Calculate earthwork quantities using the 20m-interval cross-sections over the length of the road using Civil3D. Draw the mass-haul diagram (in scale) and discuss its properties.

You can either draw the mass-haul diagram using Excel or Civil3D.

d) Prepare scale drawings of:
• The plan, showing horizontal curve details and cut-and-fill extremities.
• The longitudinal profile along the design line showing vertical grading details and cut-and-fill requirements.
• 4 ‘typical’ cross-sections (e.g., a tangent, curves, through the rock, etc.) for each route.

Evaluation

a) Compute the 20-year cost of the road on the basis of costs advised by the Department of Transport (proposed bypass and no build). This will include construction, acquisition, environmental, social and operations and maintenance costs. Relevant data can be found in Road Project Data Excel file.

b) Conduct a detailed economic evaluation using the NPW, benefit/cost ratio and incremental benefit/cost ratio methods.

c) Discuss social and environmental impacts