Highway Engineering
Combining Equations 6.4 and 6.5 with the appropriate design speeds and round- ing the resulting values as appropriate yields the ...
d 2 =Distance between the overtaking and opposing vehicles at the point in time at which the overtaking vehicle returns to its d ...
Table 6.8 should be adhered to. Where overtaking is not permitted, sight dis- tances should not greatly exceed those required fo ...
Table 6.9 details the minimum radii permitted for a given design speed and value of superelevation which should not exceed 7%. 6 ...
[Mg¥Sin(a)] +P=[(M¥v^2 /R) ¥Cos (a)] (6.7) The side frictional force,P, can be expressed as: (6.8) (mis defined as the side fric ...
(The appropriate value for desirable minimum radius given by TD 9/93 and illus- trated in Table 6.9 is almost identical – 1020 m ...
The minimum offset clearance Ms required between the centreline of the highway and the obstruction in question can be estimated ...
Alternative method for computing Ms If the radius of horizontal curvature is large, then it can be assumed that SD approximates ...
If the sight distance length SD lies outside the curve length R, the following formula can be derived for estimating the minimum ...
Two formulae are required for the analysis of transition curves: S=L^2 /24R (6.24) L=V^3 /(3.6^3 ¥C¥R) (6.25) where Sis the shif ...
must be shifted inwards from its initial position by the value Sso that the curves can meet tangentially. This is the same as ha ...
176 Highway Engineering Example 6.5 A transition curve is required for a single carriageway road with a design speed of 85 km/hr ...
Geometric Alignment and Design 177 Example 6.5 Contd Shift: Using Equation 6.24: S=L^2 /24R=(86.03)^2 ∏ 24 ¥ 510 =0.605 m Length ...
6.6 Vertical alignment, 6.6.1 General Once the horizontal alignment has been determined, the vertical alignment of the section o ...
ble in order to ensure adequate surface water drainage. (This can also be dealt with through the provision of a drainage system ...
should therefore normally be designed to the absolute minimum K value detailed in Table 6.12. For both crest and sag curves, rel ...
When x =L: (6.39) (q being the slope of the second straight line gradient) Therefore: q =kL+C =kL+p (6.40) Rearranging Equation ...
where x is the distance along the curve measured from the start of the vertical curve and y is the vertical offset measured from ...
6.6.5 Crossfalls To ensure adequate rainfall run-off from the surface of the highway, a minimum crossfall of 2.5% is advised, ei ...
The driver’s eye height H 1 The height of the object on the highway H 2 Minimum curve length Lm. In order to estimate the ...
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