PROBLEM $1$

a$)$ A two$-$lane rural highway has a curve of $8$o$.$ The design speed is $50$ mph$.$ What

would be the superelevation e on this curve such that the value of f $($coefficient of

side friction$)$ would be zero at the design speed? For this value of e $,$ what would

be the value of f for a vehicle stopped on the curve?

b$)$ The horizontal curve below is on a two lane road with $12\mathrm{.}0$ foot lanes and no

shoulders. In order to develop a $6\mathrm{.}25\%$ superelevation on the $250$ foot radius

curve, determine the stationing of the BC and the EC$.$ You must assume the

following:

$$ the slope ratio of the outer edge of pavement in relation to the centerline of

the roadway $($or r$)$ is $0\mathrm{.}5\%.$

$$ While developing superelevation first on tangent then on curve, the

$$Adverse Crown Removed$$ section is achieved at station $100+00,$ and two

thirds of the superelevation runoff is developed on the tangent at BC$\mathrm{.}4550\text{'}12"$

$250\text{'}$

EC

STA $100+00$ BC

o