Prefeasibility Access Road Design-Revised
5
ROAD DESIGN CRITERIA
Typical
Section -
Exhibit D-2
Rev.1
Large Cut
Sections -
Exhibit D-3
Large Fill
Sections -
Exhibit D-4
Minimum Driving Lane Width
12 Ft.
12 Ft.
12 Ft.
Minimum Shoulder Width
4 Ft.
4 Ft.
4 Ft.
Minimum Ditch Depth
3 Ft.
3 Ft.
n/a
Flat Bottom Ditch Width
10 Ft.
20 Ft.
n/a
Maximum Fill Slope
n/a
n/a
10:1, 3:1
barn roof
Maximum Foreslope
6:1
6:1
n/a
Maximum Backslope
6:1
2:1
n/a
Maximum Road Grade
6%
6%
6%
Maximum Speed Design
40 MPH
40 MPH
40 MPH
Expected Signed Speed Limit
30 MPH
30 MPH
30 MPH
Minimum Approach Radii
80 Ft.
80 Ft.
80 Ft.
Stopping Site
Distance for
40 MPH
Design Speed
3% Downgrade
315 Ft.
315 Ft.
315 Ft.
6% Downgrade
333 Ft.
333 Ft.
333 Ft.
3% Upgrade
289 Ft.
289 Ft.
289 Ft.
6% Upgrade
278 Ft.
278 Ft.
278 Ft.
Decision Site
Distance for
40 MPH
Design Speed
Avoidance Maneuver A
330 Ft.
330 Ft.
330 Ft.
Avoidance Maneuver B
690 Ft.
690 Ft.
690 Ft.
Avoidance Maneuver C
600 Ft.
600 Ft.
600 Ft.
Avoidance Maneuver D
715 Ft.
715 Ft.
715 Ft.
Avoidance Maneuver E
825 Ft.
825 Ft.
825 Ft.
Avoidance Maneuver A: Stop on rural road t=3.0s
Avoidance Maneuver B: Stop on urban road t=9.1s
Avoidance Maneuver C: Speed/path/direction change on rural road t varies between 10.2s and 11.2s
Avoidance Maneuver D: Speed/path/direction change on suburban road t varies between 12.1s and 12.9s
Avoidance Maneuver E: Speed/path/direction change on urban road t varies between 14.0s and 14.5s
III INTERSECTION SIGHT DISTANCE AND ACCIDENT
HISTORY
HDR|Stetson Engineering performed onsite inspections of the entire roadway
between Four Corners (in the Bear Lodge Mountains) and the Hydromet plant site in
Upton to view the condition of the haul route and more specifically the existing
intersections and sight distances. When working with the design vehicle established
for this project, it is important to have large radii at all intersections to allow the
truck to make turns without encroaching on other lanes of traffic. Good sight
distance is also a priority because of the length of time the design vehicle will be in
