Week 10: Flashcards
What is stake value? (chainage)
Measurement from the centreline of the construction from the beginning.
What types of sections are taken?
Long sections - Along centre line of proposed construction.
Cross sections - Perpendicular to the centre line, at 20m intervals.
How do you combine straights?
Circular curves - Constant radius.
Transition curves - Between circular curve and straights has a variable radius.
What is the angle between the two straights?
Deflection angle.
theatre = inverse sin(c/2R)
What do you call the beginning of the circular curve? And the end of the circular curve?
Beginning - BC or BCC.
End - EC or ECC.
Explain what a chord is.
What do we often have to determine to do with road design?
The volume of materials required, as this relates to the cost of the materials for the project.
What are the two types of volume needs?
Cut - The excavation of excess material.
Fill - The relocation, shaping and compaction of material.
What is the ideal situation with cut and fill?
The material cut should be used to fill. Equal amounts of material needed to be moved.
What terms explain this process? When soil is excavated from its natural state it undergoes expansion to occupy a greater volume than the space is occupied previously.
Expansion and compaction.
What are the two methods to determine Volume?
End-area Rule: Volume = L x ((A1 +A2)/2)
Prismoidal formula: Volume = (L1(A1 +4Am +A2))/6 Need 3 cross sections to use the prismoidal formula. Only need 2 cross sections to use end-area rule.
