Horizontal Alignment Design

$R=470m$

Traffic lane width of this road is $3\mathrm{.}5m_{?}$ and its shoulder width is $1\mathrm{.}5$ m $.$ The verge is not required

for this road, which means the shoulder edge will directly connect to the batter slope.

The normal crossfall of traffic lanes is $-3\%$ and the normal crossfall of road shoulders is $-5\%.$

The required batter slope of cut is $1$:$2,$ and the batter slope of fill is $1$:$3($vertical: horizontal$).$

The maximum depth of cut is $15m_{?}$ and the maximum height of fill is $10$ m $.$

The average shrinkage factor of soil in the area where the road will be constructed is $5\%.$

The earthwork free haul distance given by the contractor is $250$ m $.$

Other required information, if not given, can reasonably be assumed based on your engineering $|$

judgements and Austroads Guides.

In this chapter, you are required to complete the following tasks:

$$ Task $3\mathrm{.}1$: Determine all superelevation parameters of this road $($such as e$,$ Le$,$ Sro, Tro, etc.$).$

$(2\mathrm{.}5$ marks$)$

$$ Task $3\mathrm{.}2$: Design horizontal alignment of this road including tangents, circular curves and

transition curves. Then, calculate the geometric parameters of the horizontal alignment and

determine the chainages $($CH$)$ of all control points on the horizontal curve $($e$.$g$.,$ TS$,$ SC$,$ Mid,

CS$,$ ST$,$ etc.$)($Note: checking of all relevant design constraints should be presented in the

report$).(4\mathrm{.}5$ marks$)$

$$ Task $3\mathrm{.}3$: Draw the horizontal alignment of the road on the topographic map showing the

lengths of tangents, circular curve and transition curves, as well as the CHs of all control

points $($e$.$g$.,$ TS$,$ SC$,$ Mid, CS$,$ ST$,$ etc.$).(1\mathrm{.}5$ mark$)$

$$ Task $3\mathrm{.}4$: Determine the CHs of four points on your horizontal curve where the superelevation

of the shoulder and traffic lane on the outer side of the horizontal curve start to develop and

where they end $($i$.$e$.,$ back to the normal crossfall$)(2$ mark$)$