Problem #$1$: Tangent$-$to$-$Curve Transition

Given:

The information shown in Figures $1$ and $2,$ along with the data provided below, should be

used to establish the horizontal alignment and vertical profile:

Design speed: $60mph($for entire alignment$)$

Setting: Rural

Normal crown cross$-$slope: $2\%($high point at roadway centerline$)$

Maximum rate of superelevation: $8\%$

Cross$-$section: Two$-$travel lanes $($one in each direction$)$ @ $12$ feet wide

Find:

a$.$ Length of superelevation transition $($tangent runout plus superelevation runoff$)$ for

horizontal curve #$1.$

b$.$ Draw the superelevation transition profile $($show transition at the beginning and

end of the curve $[$PC and PT stations should be shown on profile piot$])$ for

horizontal curve #$1.$ The axis of rotation for the tangent$-$to$-$curve transition is

the centerline of the roadway.

c$.$ Draw cross$-$sections $($including stations$)$ at the beginning of the superelevation

transition, removal of adverse crown, uniform cross$-$slope, and location where full

superelevation is first attained for horizontal curve #$1.$ Show cross$-$sections for

both ends of transition $($PC and PT ends of curve$),$ including the elevation data.

The minimum length of vertical curve, based on the design speed, should be used

for the elevation computations.

d$.$ Compute the side friction at the mid$-$point of horizontal curve #$1.$

e$.$ Horizontal curve #$2$ is located at PI Station $200+00.$ Is there enough space

between the curves to provide an adequate tangent$-$to$-$curve transition? Explain.

f$.$ What is the minimum horizontal sightline offset that should be provided along the

inside of both horizontal curves shown in Figure $1?$PI #$2$

STA $200+00$

BEGIN

STA $100+00$

Figure $1.$ Horizontal Alignment for Problem #$1$