<< Click to Display Table of Contents >> Navigation:  Design > Vertical > Analysis > Visibility

Purpose

To highlight lengths on a vertical alignment summit curve where vertical sight lines are not to a specified standard.

 

Operation

Pick the datum line and pick the Vertical Alignment 2D Polyline. Enter values into the dialogue :-

 

Eye height    

Driver eye height above the alignment.

 

Object height    

Target height above the alignment.

 

Sight distance    

Horizontal distance for analysis.

 

Increment    

Interval for calculation (1 metre would be typical).

 

The start and end chainages will default to the start and end of the alignment (the 2D Polyline with direction from left to right). Note that to run the visibility calculation from right to left the start chainage will be greater than the end chainage. There are two outputs :-

1.Report file.

2.Draw Lines, default colour is red to show lengths of bad visibility.

 

Example report file :-

KeyTERRA-FIRMA - Vertical visibility study

 

Eye height: 1.050

Object height: 0.260

Sight distance: 70.000

Increment: 0.500

Eye start chainage: 0.000

Eye end chainage: 385.500

Direction: Ascending chainages

 

Bad visibility between chainages 166.000 and 182.000

Bad visibility between chainages 328.000 and 332.500