Road Profiles Flashcards
What is the most common scale used for plan view?
what elements are included in plan view?
1: 5000 is the standard
1: 2000 for detailed roads
Includes streams, legal boundaries, stream crossing, Reference points, curves, culverts, right of way width.
What is the difference between a P-line and an L-line
P-line (preliminary line) first traversed line.
L-Line (final road location after design correction.
On easy roads there are no changes
What is Profile View?
- A vertical representation of the ground profile
- Designed road scale
- Exaggerated vert. alignment (1:200 vert, 1:2000 horiz.)
Why is vert allignment exaggerated in profile view?
To bring attention to even minor changes in grade
What does profile view show?
- Ground line from survey
- Designed grade of L line
- Culvert location and specs
- Terrain features and existing structures
What does ground line above or ground line below grade line imply?
Above: cut
Below: fill
What does full cut imply?
Road below ground line
What does cut and fill imply?
Part of road cut to grade line and part of road filled to gradeline
What does fill section imply?
Road is above ground level
What is site preparation?
- Clearing woody debris and overburden out of the way
- 3m clearance from top of cut slopes and toe of fill
What is excavation?
- movement of material after site prep
- Solid rock or (OM) Other material
List the materials
- No organics
- Rock (requires blasting or ripping)
- OM: Includes gravel and sand
What is grading?
Rough excavation to form the roadbed to the gradeline
What is sidecast?
Material used to build up the lower side of a road on a slope.
What is it called when material is excavated from one spot and filled into nearby gullies or dips?
What about when it needs to be moved a long distance?
Short distance: “longitudinal movement”
long distance: end hauling
What does wasted refer to?
Excess Material that is discarded. Generally frowned upon.
What is a rule of thumb with slopes when roadbuilding?
If sideslope over 60%, hire a geotech to sign off on plans.
What are some uses for rock that is too big to be used in surfacing?
Use as sidecast or
Use to stabilize culverts
What is ballasting?
Also called surfacing. ballasting is when suitable blasted material is used to improve the running surface of a road.
What are the road standards of a class 5 road
- Stabilized subgrade 5m
- Ditches 1m deep
- 50% Slope to ditch from road
- 20m clearing width
What is important about cut and fill slopes
- The more erodable the material the lower the slope
What does a “balanced design” imply
Cut and Fill should be near equal to acheive balance and minimal waste
What is “expansion and Compaction?”
What does it imply
Materials get bigger when they are dug up and smaller when they are packed into a hole.
Correction factors must be applied to calculate their equivalant fill volume.
What are compaction factors?
- Excavated OM compacts to 75% of its original volume
