It develops students' ability to design road geometric elements including roadside drainage.
Details/Questions
On the contour plan shown in attached map, a two-lane two-way road is to be designed for a target speed of 80km/hr to 100km/hr speed joining Point A (CH0+000) and Point B. The design covers route location, horizontal and vertical alignments, cross-sectional elements, earthworks and road drainage design to achieve the most safety and economical outcome.
The following are the requirements:
• At Point A, the reduced level of the road is to be RL65.000.
• At Point B, the reduced level of the road is to be RL75.000.
• There will be only one horizontal curve and only one vertical curve.
• The truck traffic is negligible. Hence consider only cars for design.
• Radius of horizontal curve [R= LN(full student ID)x 14] is upward rounded to 10m. Use average student ID if two students are working together. LN is natural log function.
• Length of vertical curve [L= LN(full student ID)x7] is rounded to nearest 5m. Use average student ID if two students are working together. LN is natural log function.
• Side slope of cut is 1:1, fill is 1:2. Shrinkage factor = 10%.
• Maximum height of fill is 2.5m and maximum depth of cut is 3.5m.
• Uniform ground slope at a particular chainage can be assumed. It can be obtained from contour map by joining two points at two sides of the road centreline, each at 20m distance perpendicular to the road centreline (approximation will be sufficient).
• Lane width= 3.6m, sealed shoulder width= 1.2m.
• Normal crossfall is -3% for lanes and -5% of sealed shoulder.
• Rainfall intensity is 80mm/hr (1 year ARI) and 120mm/hr (10 year ARI)
Within the constraints described above, design should include the following design elements (note: you cannot finalise these elements in sequence and iterative process is required):
1. Sketch two alternative alignments connecting Point A with Point B. Choose one alignment for your design. Justify.
2. Locate your alignment considering both vertical and horizontal controls. Coordinate both horizontal and vertical alignments. Provide alignment sketch with all design data (e.g., CHs/deflection angle in horizontal alignment, CHs/RLs/grades of vertical alignment.)
3. Design horizontal alignment (tangents and circular curve- also transition curves if required). Develop a horizontal alignment design table.
4. Design vertical alignment (grades and parabola) in detail. Develop vertical alignment design table.
5. Draw an appropriate longitudinal section (profile view) showing both vertical and horizontal curves, depth of cut/fill etc. at 100m interval (in scale).
6. Design superelevation for your road.
7. Determine and tabulate the cross section levels (left end of the shoulder, left end of lane,
8. Design side drain for your road for the runoff accumulated from road surfaces only.
9. Draw cross-sections at 100m interval (depths of side drain and pavement can be neglected). Manually show your area calculations for three typical cross-sections (fully cut, fully fill and partially cut/fill) and indicate all cross-sectional areas in the drawings (note: you do not have to draw in scale but you need to show all dimensions).
10. Calculate earthwork quantities using 100m cross-sections over the length of the road. Draw mass-haul diagram (in scale) and discuss the properties of your mass-haul diagram.
11. Check stopping sight distance on horizontal and vertical curves as required.
12. Check road-ponding/aquaplaning safety as required