One main street(east- west) and cr

[lila]

One main street(east- west) and cross street(north-south) are intersecting. Cross street is to be designed with a crown at the center. The grade of main street is sloping from west to east. In the intersection design, how can we design an intersection without developing a low point near intersection. The problem is, for cross street, in order to have 2% slope we have to lower the elevation from crown towards edge of pavement. On the otherhand, for main street we have to lower the grade from west to east. So, i have a problem at north west corner. Both are contradicting. Any suggestions????
Thanks
Lila

 

[dellbs]

lila,

Does traffic have to stop on cross street? Is main street a through road? Is there to be curb and gutter?

If I understand your description, main street slopes downhill from west to east. What is the grade? If traffic has to stop on cross street before entering main, then design main street as if there wer no cross street. That is, carry the road crown through the intersection. Once you ahve done this you can check your grades to see how best to grade cross street at the intersection to keep runoff from collecting where you don't want it. Is there a storm drain system there? You may need to install a catch basin at a low spot.

Carry your crown on cross street only as far as the end of your curb or pavement return (if traffic must stop) then "flare it out" to match the flow line of main street. You might need to tweak the radius return grades to force drainage to flow where you want it. Don't get your slopes too flat or you may end up with "bird baths" when the final paving is done.

Intersection can be very challenging to design, I enjoy doing them. There's generally always a solution. Think in 3-D.

Good luck,
David