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Why Grade? Because the Best Can Do This?
Important Note: Notice the graceful transition from the building pad to the public walk in the right of way.
Extremely thoughtful & skilled work demonstrated in setting the building pad elevation.
1Tuesday, October 26, 2010
But Why Roads?
To get you from the grace & comfort of home here....
2Tuesday, October 26, 2010
To Here
Road design is complicated technically and specialist road engineers and high end software are involved
LA’s work with Engineers in Corridor Planning & Scenic Byway Design
Generally LA’s design minor drives & and almost always in conjunction with a qualified engineer
3Tuesday, October 26, 2010
Basic Geometry of a Simple Circular Curve
Two fundamental elements are the curve that connects two tangents
Tangents are straight lines
The radius of the Curve is the same radius as the radius of the circle that the Curve is a portion of
Curve RadiusTangent
Tangent
4Tuesday, October 26, 2010
Types of Circular Curves: Reverse Curve
Reverse Curve: Two curves moving in opposite direction linked by a tangent
Note: The radii of the two curves need not be the same
The radius of any curve must meet the minimum dimension for the design speed of the road being designed
Tangent Linking Curves
5Tuesday, October 26, 2010
Curve Radii for Design Speeds
Note, higher design speeds require larger minimum radii for safety
Your assignment is a simple two lane drive with an intentionally slow design speed
6Tuesday, October 26, 2010
Types of Circular Curves: Compound Curves
Compound Curves: A single continuous flowing curve with two (or more) radii
Note how the Center of Curve (O) falls on the radius of the larger radius curve
Note that the difference in radii between the two curves should not be more than 50%
O
7Tuesday, October 26, 2010
Nautilus
Growth in a compound curve the radii of which are in proportion to one another using the golden ratio
8Tuesday, October 26, 2010
Types of Circular Curves: Broken Back Curves
Broken Back Curves: Two curves moving in the same direction separated generally by a short tangent
Can be awkward to maneuver through, breaks rhythm of movement. can present sight line problems, only for very slow speeds
9Tuesday, October 26, 2010
Circular Curve Elements: Point of Curvature (PC)
The Point of Curvature (PC) is the point where the curve begins at the end of the entering tangent
10Tuesday, October 26, 2010
Circular Curve Elements: Point of Tangency (PT)
The Point of Tangency (PT) is the point where the curve ends at the outgoing tangent
Note: Stationing is a standard means of horizontally locating critical points along the centerline of a road’s horizontal profile
We will use stationing for this assignment
Entering Tangent
11Tuesday, October 26, 2010
Circular Curve Elements: Point of Intersection (PI)
The Point of Intersection (PI) is the point where the extension of the entering and exiting tangents intersect
Important Note: The tangent line between the PC & PI will always be the same length as the tangent line between the PI and the PT
Exiting Tangent
12Tuesday, October 26, 2010
Radii Characteristics
Important Notes: Other than for Compound Curves, the dimension of the radius for any specific curve remains constant
The radius of a curve is described by a line perpendicular to the entering tangent and the outgoing tangent at the PC & PT respectively
13Tuesday, October 26, 2010
The Center of Curve (0)
The Center of Curve (O) is the point created by the intersection of the radius lines extended down perpendicular from the tangents at the PC & PT.
You insert your compass point in O to ‘swing’ your radius
14Tuesday, October 26, 2010
Tangents Entering & Leaving the Curve
For our assignment we will consider the first entering tangent the first tangent entering the first curve from the left of the sheet ~ Point A
Tangent Entering the curve
Tangent Leaving the curve
15Tuesday, October 26, 2010
Included Angle (I)
The Included Angel I (I) is the angle created by the intersection of the extended tangents
Note: I also is equal to the angle described by the intersection of radii extended from the PC & PT
16Tuesday, October 26, 2010
Straight Curb ~ No Gutter Pan
17Tuesday, October 26, 2010
Straight Curb ~ No Gutter Pan
Typical Section of a Straight Curb w/o gutter pan.
17Tuesday, October 26, 2010
Straight Curb ~ No Gutter Pan
Typical Section of a Straight Curb w/o gutter pan.
Road surface abuts vertical face of the curb.
17Tuesday, October 26, 2010
Poured in Place Concrete Curbs w/Gutter Pan
18Tuesday, October 26, 2010
Poured in Place Concrete Curbs w/Gutter Pan
Note direction horizontal face of gutter pan slopes. This gutter pan slopes away from the curb
18Tuesday, October 26, 2010
Poured in Place Concrete Curbs w/Gutter Pan
Note direction horizontal face of gutter pan slopes. This gutter pan slopes away from the curb
Gutter pan sloped either toward curb or away from curb depending on drainage needs. The lower gutter pan slopes to the curb
18Tuesday, October 26, 2010
Poured in Place Concrete Curbs w/Gutter Pan
Note direction horizontal face of gutter pan slopes. This gutter pan slopes away from the curb
Gutter pan sloped either toward curb or away from curb depending on drainage needs. The lower gutter pan slopes to the curb
Which of these would we use for our road project & why?
18Tuesday, October 26, 2010
Drain Inlet
Drain Inlets have only an outlet pipe. They have no inlet pipe.
Drain Inlets have no Sump below the outlet pipe
Note “Bumble Bee” Grate
19Tuesday, October 26, 2010
Catch Basin (CB) Characteristics
Note Sump: Volume of space below pipes entering & leaving for debris & sediment to settle & Collect
Note Pipe entering & leaving.
Catch Basins have a pipe in & out
For our project, the outlet pipe shall have an invert@ the CB 2” lower than the invert of the pipe coming into the CB where it enters
20Tuesday, October 26, 2010
Catch Basin Installation
Note Concrete Structure on Top of CB below with Iron Inlet secured in concrete
CB & Inlet installed prior to placement of road compacted aggregate sub-base and finish surface
CB Inlet must be precisely set to proper Rim Elevation as indicated on Grading & Drainage Plan
21Tuesday, October 26, 2010
Culvert Basics
22Tuesday, October 26, 2010
Culvert Basics
Invert Elevation (INV. IN, INV. OUT.) Invert refers to the Elevation of the Bottom of the Pipe
22Tuesday, October 26, 2010
Culvert Basics
Invert Elevation (INV. IN, INV. OUT.) Invert refers to the Elevation of the Bottom of the Pipe
INV. EL @ CL of road must be 2’-3” above top of pipe directly below it to achieve a minimum of 2 FT of cover over the top of the pipe.
22Tuesday, October 26, 2010
Culvert Basics
Invert Elevation (INV. IN, INV. OUT.) Invert refers to the Elevation of the Bottom of the Pipe
INV. EL @ CL of road must be 2’-3” above top of pipe directly below it to achieve a minimum of 2 FT of cover over the top of the pipe.
Note interaction of contours with head wall
22Tuesday, October 26, 2010
Culvert Basics
Invert Elevation (INV. IN, INV. OUT.) Invert refers to the Elevation of the Bottom of the Pipe
INV. EL @ CL of road must be 2’-3” above top of pipe directly below it to achieve a minimum of 2 FT of cover over the top of the pipe.
Note drafting of head wall beyond in concept section
Note interaction of contours with head wall
22Tuesday, October 26, 2010
Culvert Basics
23Tuesday, October 26, 2010
Culvert Basics
Note location of Catch Basins or either side of road against the curb
23Tuesday, October 26, 2010
Culvert Basics
Note location of Catch Basins or either side of road against the curb
Note longitudinal flow pattern of road
23Tuesday, October 26, 2010
Culvert Basics
Note location of Catch Basins or either side of road against the curb
Note longitudinal flow pattern of road
Note flow pattern resulting from cross slope from crown of road to face of curb
23Tuesday, October 26, 2010
Culvert Basics
Note location of Catch Basins or either side of road against the curb
Note longitudinal flow pattern of road
Note flow pattern resulting from cross slope from crown of road to face of curb
Note flow pattern from low point on road center line to the catch basins
23Tuesday, October 26, 2010
Gentle Swale Flowing to Culvert w/Headwall
This Culvert Runs beneath the entry drive to this park
It likely connects with what appears to be a ‘natural’ vegetated swale on the other side of the road
Note the simple yet elegant curved headwall
24Tuesday, October 26, 2010
Contract Document Plan & Section of Culvert Outlet
25Tuesday, October 26, 2010
Contract Document Plan & Section of Culvert Outlet
Note washed cobble at outlet to absorb energy of water flow at outlet to prevent erosion
25Tuesday, October 26, 2010
Contract Document Plan & Section of Culvert Outlet
Note washed cobble at outlet to absorb energy of water flow at outlet to prevent erosion
Note reinforcing filter fabric beneath end of pipe and cobble to prevent erosion
25Tuesday, October 26, 2010
Contract Document Plan & Section of Culvert Outlet
Note washed cobble at outlet to absorb energy of water flow at outlet to prevent erosion
Note reinforcing filter fabric beneath end of pipe and cobble to prevent erosion
• Note slope on pipe. Our culvert pipe shall have a minimum slope of 1% & maximum slope of 2%
25Tuesday, October 26, 2010
Concept Alternate Outlet for Culvert
26Tuesday, October 26, 2010
Concept Alternate Outlet for Culvert
Prepared Soil & Root Zone for bio-physical treatment of pollutants in runoff
26Tuesday, October 26, 2010
Concept Alternate Outlet for Culvert
Prepared Soil & Root Zone for bio-physical treatment of pollutants in runoff
Reinforcing Stone inter-planted w/flowering plants
26Tuesday, October 26, 2010
Concept Alternate Outlet for Culvert
Prepared Soil & Root Zone for bio-physical treatment of pollutants in runoff
Reinforcing Stone inter-planted w/flowering plants
Scarify subsoil to promote infiltration
26Tuesday, October 26, 2010
Concept Culvert Outlet Plan
Concept Plant of Culvert Outlet
Cobble 4” to 8” dia. to absorb energy of outflow and not get washed away
27Tuesday, October 26, 2010
Head Wall & Larger Scale Culvert Pipe
28Tuesday, October 26, 2010
Head Wall & Larger Scale Culvert Pipe
Note Contours on Headwall
28Tuesday, October 26, 2010
Head Wall & Larger Scale Culvert Pipe
Note Contours on Headwall
Note Contours on Side Slope of swale, 3:1 max, 4:1 a better maximum side slope
28Tuesday, October 26, 2010
Head Wall & Larger Scale Culvert Pipe
Note Contours on Headwall
Note Contours on Side Slope of swale, 3:1 max, 4:1 a better maximum side slope
Note Swale Signature at bottom of swale
28Tuesday, October 26, 2010
Head Wall & Larger Scale Culvert Pipe
Note Culvert is beneath road & top of pipe has soil cover
Note Contours on Headwall
Note Contours on Side Slope of swale, 3:1 max, 4:1 a better maximum side slope
Note Swale Signature at bottom of swale
28Tuesday, October 26, 2010
Culvert Outlet w/No Reinforcement of Land Surface
This condition on a slope will eventually lead to accelerating erosion of the slope which will continue until actions arrest and repair the damage made
29Tuesday, October 26, 2010
The Immediate Process ~ Stay Tuned for Step 2
Analyze existing conditions, vegetation, natural features, views, built structures, topography, high points, low points, water conveyance patterns etc.
Read & understand the structure of the existing land form. What does it suggest for a road alignment.
Rough out a free hand alignment with design speed criteria in mind for minimum radii
Begin to formalize horizontal curve layout geometry
Engage the iterative process and be willing to explore & change options
Draft the preferred option with the curb line, the shoulders and walk
30Tuesday, October 26, 2010