Quantity: Flooding and Sight Distance

Important Terminology

• Station: 100 feet.
  • Projects start at station 0+00
  • Stations are written as the number of hundreds + remaining. Ex: The first station is 1+00 and the second station would be written as 2+00.
  • If you are 11+ 62.5 stations from the start of a project, you are 1162.5 feet from the start of the project.
• Slope: (use feet for horizontal distance)
• Grade: (use stations for horizontal distance)
  • 3% grade means for every 100 feet horizontal, the rise in the road is 3 feet vertically
  • 3% = .03, but using stations would be reported at a grade of 3

Civil Engineers at NCDOT measure using stations instead of feet. From Crests and Sags part 1, you determined that the curve elevation function for the 400-foot vertical curve (horizontal width) with a beginning grade of

-5.1% and ending grade is 2.4% is where x is in horizontal feet.

1. Use the formula , to determine value of a in stations.

1. Rewrite the equation where x is in stations.

1. Rewrite the following horizontal distances in feet to stations. Then use the stations and the equation you found from #2, to determine the elevations of the curve.

Horizontal Feet	Stations	Vertical Elevation
0 feet
50 feet
100 feet
150 feet
175 feet
200 feet
225 feet
250 feet
300 feet
350 feet
400 feet

1. Suppose in thisscenario thestormwater drop is placed 1.4 stations from the VPC.
   1. Explain why this is not optimal placement for the stormwater drop.

1. Where should thestormwater drop be placed for optimal roadway drainage? Determine the elevation for the appropriate storm drain placement.

1. During a hurricane event, the model predicts stormwater will rise to an elevation of 109.00 feet. Determine the interval, in stations, in which the roadway floods.

1. Why do you think the roadway will still flood even though the drain is at its optimal location for roadway drainage? What other factors may be contributing to the flooding issues?