Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Basic question (highway horizontal curves)

Basic question (highway horizontal curves)

Basic question (highway horizontal curves)

It's always been convention that the stationing from the beginning of a horizontal curve to the point of intersection is equal to the tangent, and the stationing between the beginning of the horizontal curve to the end of the curve is equal to the length of the curve. I've been just accepting it because that what the book says, but how does it make sense? How would it be mapped out in real life? I would think that we need to station from the tangent or station from the curve, but why then do stations work like I described? Thanks.

RE: Basic question (highway horizontal curves)

Roads are typically staked ("mapped out in real life") along the centerline or at a designated offset from centerline.

RE: Basic question (highway horizontal curves)

So I think there's a discrepancy between what you're seeing in a text and the rigorous definition of the stationing convention. Stationing starts at a point of beginning (POB), then follows the alignment through the series of curves etc increasing along the distance of the line. So for a given curve, the minimum value would be at the point of curve (PC), maximum at point of tangency (PT), with the Point of Intersection at some intermediate value (that isn't half) of the station at the PT.

So hypothetically, for a curve with a start station of 1+00, and length of 100 feet, the PT would be at Sta 2+00. However, the tangent distance (T) is proportional to the radius and Delta angle (T=R*tan(Delta/2))

Seeing this applied to a hypothetical problem.
Radius = 1909.86'
Degree of curve: 3^00'00"
Tangent length: 422.24
Delta = 24^56'
Assume PI at Sta 568+24.33
Find PC and PT stations

L_c = Delta/Degree of curve * 100 = 831.11 feet
PC = PI- Tangent = (568+24.33) -(4+22.24) = 564+02.09
PT = PC + L_c = (564+02.09) + (8+31.11) = 572+33.20

(From the CDOT Survey Manual Chapter 8 at https://www.codot.gov/business/manuals/survey/chap...)

Chris Enright
PE, Colorado
Roads and Trains

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close