8.1. Two straights BA and AC

Try these first

1. 1.

   What is the formula for calculating tangent length?

   Hint

   Think about what parameters are involved in the tangent calculation.

2. 2.

   Define the term 'deflection angle'.

   Hint

   Consider how it relates to line intersections.

3. 3.

   What does the deflection angle represent?

   • The angle of line intersections
   • The radius of the curve
   • The length of the curve

   Hint

   Think about the measurement that represents curvature.

4. 4.

   True or False: The length of the curve can be calculated directly from the radius.

   • True
   • False

   Hint

   Consider how both parameters are used in the formula.

5. 5.

   A road layout needing to connect two straights, has a PI of 2000 m with a deflection angle of 72°. Calculate the tangent and curve lengths required to set this out using a radius of 80 m.

   Hint

   Use the formulas correctly to derive each component.

6. 6.

   Considering a deflection angle of 90° and a radius of 100 m, calculate the offsets and the positions of pegs every 10 m along a 33 m curve.

   Hint

   Use the offset calculations learned in the section for each step.