×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

Stopping Sight Distance

Stopping Sight Distance

Stopping Sight Distance

(OP)
Hi,
It is noticed in the newest version of AASHTO (highways) that the vertical curve length calculated from the SSD (stopping sight distance) is modified relative to that of the previous version; however, this modification is to the worse not to the better.
So, in the newest version (pages 271,272), Length L is calculated as AS2/658(when S is less than L) compared to AS2/404 in the 1994 version. The difference between the 2 results is mainly due to the change in the object height from 15 cm in 1994 to 60 cm in the new version. Hence by decreasing L the design speed on the highway is reduced and consequently reduction in quality of the highway.
So what do you think about that. Any interpretations are welcome.

Regards...
 
 

RE: Stopping Sight Distance

This has been noted by several people I know and they entend to to keep using the old standard.  Sight distance is a pretty basic highway design standard and the fact that so little has been writen about this change bothers me too.  I think it should be 20" min for the object because that is about the height of the stop lights on a small car.

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!


Resources