LARE SECTION 3 2021 Flashcards
What is an important factor in how soil will behave under different conditions?
Grain size distribution
What are issues for engineers regarding soil?
The variations caused by grain size distribution, clay mineralogy, and organic content in the presence of water
What are the 12 soil classifications?
- 4 coarse-grained soils
- 4 fine grained soils (half the soil is silt or clay) and
- 4 combinations of fine and coarse grained soils
(Classification also includes 3 organic soils)
What type of soils are preferred for sub-grade and base materials?
Coarse grained soils (GW)
*Poorly graded gravels (GP) and silty gravels (GMd) may be used under some circumstances
Definition: Water > 50%, high plasticity (very cohesive or sticky clay)
High Liquid Limit
Definition: Water Content < 50%, low plasticity
Low Liquid Limit
Definition: Soils that include particles of all sizes
Well graded soils
Definition: The moisture content at which a soil deforms plastically
Plastic Limit (PL)
Moisture vs Plastic: If a soil can be rolled into finer threads without cracking then…
It contains MORE moisture than its plastic limits
Moisture vs Plastic: If a soil can be rolled into finer threads and cracks before 3mm is reached then…
It contains LESS moisture than its plastic limits
What is the numerical difference between the LL (Liquid Limit) and PL (Plastic Limit)?
Plasticity Index (PI)
A PI (Plasticity Index) provides what?
Gives the range of moisture in which a soil behaves as a plastic material
A PI (Plasticity Index) over 15 is a good indicator of what?
An expansive soil
Regarding soil, what does porosity refer to?
The amount of pore space in a soil.
Related to the grain size and distribution and consolidation
Regarding soil, what does permeability refer to?
The rate at which water will freely drain through a soil
What is Soil Strength?
A soil’s ability to resist deformation, which is a function of the friction and cohesion in the grain-to-grain contact in soil.
What is Soil Cohesion and what is high cohesion most often associated with?
The measure of the capacity of soil particles to stick together.
Clays
What is Shear Strength in soil?
The measure of the frictional resistance and cohesion of a soil. The shear strength of the soil is the THE FORCE APPLIED AT THE TIME OF FAILURE.
What is Bulk Density?
The weight per volume of any soil unit. The higher the bulk density, the greater the support it can provide for a foundation
Calculation for Walkways
W (Width) = V (Volume) (M) (Space Module) / S (Speed)
Stair Calculation
2R+t = 26 - 28 inches
Ramps with a slope of between 1:12 and 1:16 should be designed to not exceed…
A rise of 30 in (760 mm) or a run of 30 ft (9 m)
Flatter ramps of 1:16 to 1:20 slope may be designed to a run of…
40 ft (12m), but the maximum rise should not exceed 30 in (760 mm).
Minimum clear width of a ramp?
36 in (915 mm)
What is the acceptable cross slope for surfaces of a ramp?
No greater than 1:50.
Minimum requirements of a ramp landing? (Including at 90 degree turns)
Should be at least as wide as the ramp run leading to it and be a minimum of 60 in (1525 mm) clear.
When are handrails required on a ramp? (Both sides)
If a ramp run has a rise greater than 6 in (150 mm) or a horizontal projection greater than 72 in (1830 mm)
What is the designer trying to understand on a historic site?
The limitations and opportunities of the site in order to modify the site for the intended purpose.
Definition: Site Analysis
An attempt to understand what has already been done to the site, how and why the site was altered in the past, what role the landscape played in the past, and ultimately how to preserve, restore, or rehabilitate the
landscape.
Sight Distance design is concerned with…
Providing the operator of a vehicle with safe and adequate forward visual access.
What is known as the distance forward at which a driver has an unobstructed view of the road?
Sight Distance
What are the factors affecting Sight Distance? (Four)
- The horizontal arrangement of the road
- The vertical arrangement of the road
- The height of the operator’s eye and
- The height of the object to be seen
What is determined as a combination of the time and distance that pass from the moment of perception to reaction (PR) until the vehicle stops?
Stopping Distance
What are the four treatment types for landscapes?
- Preservation: Involves the protection and stabilising of site features rather than replacing them.
- Rehabilitation: Involves repairing and/or altering a property to be compatible for another use while preserving features of historical or cultural significance
- Restoration: Involves re-creating an accurate depiction of the historic forms or features
Reconstruction: Involves depicting through new construction the forma and features of a non surviving landscape or object.
Sight Triangle: Right lane looking left distance
275” (6.985m)
Sight Triangle: Right lane looking right distance
200” (5m)
What is the typical percentage of impermeable coverage of gross site that requires mitigation to clean stormwater before it enters the drainage system?
20 percent.
What is the typical required distance of disabled parking stalls to building entries?
100’ (30m)
What is the human cone of vision?
30 degrees vertically and
60 degrees horizontally
Bicycle Path (Dedicated Right of Way)
2400mm, 3600mm or
8’ to 12’
Bicycle Lane (Part of Road)
1500mm - 1800mm or 5-6’ min.
Designated Design Speed (Bicycles)
Typically 32km/h (20mp/h)
Up to 48 km/h (30 mp/h) for sustained down hills
Amount of open space that should be allowed for every 1000 people
Ten Acres
What is the optimal size for a neighbourhood, edge to edge?
1/4 Mile
Applied to large areas 15-20 acres or more, includes public and private improvements.
Gross Density
Used in relation to project-sized areas, smaller than 15-20 acres, and consists of the number of proposed dwelling units divided by the site area.
Net Density
Typical Density: 6 dwelling units or fewer
Single-Family Detached Houses
Typical Density: 14 dwelling units per acre
Single-Family Attached Town Houses
Typical Density: 20 dwelling units per acre
Single-Family Attached Town Houses with Garage
Typical Density: Around 10 units per acre
Two Story Attached houses
Typical Density: 18 dwelling units per acre
Garden Apartments
Typical Density: 30 dwelling units per acre
Walk-Up Apartments
Weekday Daily Vehicular Trips: Detached Single Family
9.6
Weekday Daily Vehicular Trips: Townhouses
5.9
Weekday Daily Vehicular Trips: Low Rise Apartments
6.6
Weekday Daily Vehicular Trips: High Rise Apartments
4.2
Exist where a low - permeability geological deposit, such as clay, overlies the groundwater system. In these settings, groundwater may be under a greater-than-atmospheric pressure.
Confined Aquifers
Represents a “big picture” of the community related to trends and interests in the broader region and in the state in which the local government is located.
Comprehensive Plan
Maps:
- Meets National Map Accuracy Standards and may be significantly less expensive than traditional field topographic methods.
- The ability to collect aerial photography may be hampered by vegetation that
obscures the ground and therefore may only be collected during winter months in some
areas.
Aerial Photogrammetry
Maps:
- Relatively low price
- Photography firms may be reluctant to enlarge photography to the scales useful for site planners because of the inherent distortion and inaccuracy that
can be anticipated in the resulting print, but these enlarged photos are a valuable planning and analysis tool.
Historical Aerial Photography
Name the 4 types of Transportation Plans
- State wide Transportation Plans
- Metropolitan Area Long Range Transportation Plans
- Local Transportation Plans
- Corridor Plans
The management of the interaction and impacts of human societies on the environment.
Environmental Resource Management
