Movement and Utilities Flashcards
Which vehicular circulation system generates the most visually chaotic effect?
Linear
4 basic categories of traffic arteries
- Freeways
- Highways (arterial streets)
- Collector-distributor streets
- Local access streets
Which type of street usually doesn’t allow parking, is 2-3 lanes wide, and generally has a speed limit of 35mph?
Arterial streets – highways
Why are collector-distributor streets often discontinuous?
To prevent through-traffic and reduce speeds
What is the top of the road called?
The crown
What is the transverse slope of a street?
Between 1/8” and 1/2” per foot
How wide are traffic lanes on major roads?
11-12 ft
What are minimum widths of landscape strips at the roadside?
7’ min. with trees, 4’ min. with ground cover only
What is a tangent?
Straight section of the middle of the road which may or may not be level
4 rules of thumb for laying out a road
- Two curves in the same direction (broken back) should be separated by a tangent at least 200 ft long
- Two opposing curves (reverse) should be separated by 100 ft
- Two curves in the same direction with different radii should be avoided
- Simple curves may have tangents of any length
Vertical curving road alignment involves _____ curves rather than circular
Parabolic (flattened)
Intersections on a major arterial roadway should be separated by at lease _____
800 ft
Overall length of a cul-de-sac must be no more than ___ with a minimum turnaround radius of __.
400 ft… 80 ft
Max length of a block
1,600 ft
Min curb radii on minor intersections versus major street
12 ft versus 50 ft
What is the max # of cars per hour before you need a stoplight?
750
What is the max # of cars before you need a grade separation?
3,000
Most common grade separation intersection
Cloverleaf – simple, based on right turns
What is the advantage of a direct left-turn interchange?
More complex and expensive but allows more lanes to operate at high speed in all changes of direction
When do you use diamond intersections? Advantages?
Where expressways intersect secondary roads … They are simple and cheap, using little space
Slope of on ramps vs off ramps
Up ramps: bt 3-6 %
Down ramps: 8%
Which vehicular circulation network produces the most efficient use of land… With what one helpful side effect?
Linear system… But it also generates a large amount of commercial “incubator” (new business) space
What is a reasonable minimum width for a typical parking stall?
8’-4” (20” clearance bt full size cars)
Projection and bay width for 30° parking angles…
Projection: 15’7”
Bay width: 43’2”
Projection and bay width for 45° parking angles…
Projection: 18’2”
Bay Width: 48’4”
Minimum aisle width in the center of two parking projections… Creating a bay
12’
To estimate total area needs, allow for _____ square feet of parking area per vehicle
400 SF
Shopping centers require _____ to _____ ft.² of parking for every 1000 ft.² of tenant space.
3000 ft.² to 4000 ft.²
How many parking spaces does an office building need for every 350 to 400 gross square feet of floor area?
1 parking spot
Pros and cons of 30°, 45°, 60° angles versus 90° parking angles…
90° angles are less dangerous to back out of because of greater aisle width… But the other angles are easier to maneuver the vehicle into or out of.
Why does acute angle parking take up more space?
Because of the curb length of each style, it’s length, and the triangular area at the end of each stall which is wasted.
A ramp should never be steeper than 15%… But over 10% it needs ____, and at a driveway exit at a public sidewalk that can never be more than ____.
8 foot minimum transition slopes at either end… At a ranch driveway exit the slope cannot be more than 5% so that drivers can see pedestrians.
Parking areas have to be sloped for drainage… What are the restraints?
At least 1%, no greater than 5%
In order to stand comfortably in a crowd and move about easily without body contact, a minimum of ___ square feet per person is required.
13… If there is lesson than 7 ft.² per person, pedestrians move as groups rather than individuals.
Suggested maximum walking distance
One quarter-mile to one half-mile
How much time are people generally willing to spend on most urban travel, regardless of the mode?
30 minutes
Express buses average _____ miles per hour
40 to 60
Rail rapid transit averages ______ miles per hour
40 - 70 mph
TOD
Transit oriented design
Minimum width for two wheelchairs to pass each other
60”
Walkways should not have a gradient greater than ______ or a cross gradient greater than ______
1:20 (5%) …. 1:50 (2%)
Those flared sides where an accessible walk crosses a curb… Their slope is a maximum of…
1:10
Maximum slope of an accessible ramp
1:12
In parking areas with academic or administrative functions, with 7 - 50 parking spaces, how many handicap spaces should there be?
2 minimum
In parking areas with academic or administrative functions, with 51 - 100 parking spaces, how many handicap spaces should there be?
3 min.
In parking areas with academic or administrative functions, with 101 - 150 parking spaces, how many handicap spaces should there be?
5 min.
In parking areas with academic or administrative functions, with over 150 parking spaces, how many handicap spaces should there be?
5 +2 minimum for every additional 100
Three advantages of “infill” development.
- Possible lower first cost by reusing existing infrastructure
- Less environmental impact than disturbing natural open space
- Higher density development for more efficient use of infrastructure
Five general principles for underground utility locations
- Wastewater lines, because of the gravity flow requirements, have first priority.
- Trunk (main) lines shouldn’t be located in major traffic arteries
- Trunk lines for several utilities should not be located in the same street
- Reserve the center of the street for waste water lines (unless the street is superduper wide enough to accommodate a dual wastewater system, separate waste lines for each side).
- All utility installations required for the next five years should be installed before street is paved, including service lines to the curb or property lines
How many feet of clearance do you need between the water supply and the sanitary sewer?
10’
The five primary components of a water supply system
- Water sources, including lakes, rivers, streams, and wells
- Transmission mains, including aqueducts, canals, and pipelines
- Water treatment plants
- Distribution systems
- Metered connections
Grades are required to transport solids
One half to 2%
Desired velocity of solid materials
No less than 2 1/2 ft./s and no more than 10 ft./s
What is a “force main”?
Where ever waste is pumped over extensive horizontal distances
Five components of a typical wastewater system
- waterway
- Outfall and treatment plant
- Trunkline/interceptor
- Submains
- Laterals
Gas pipes are made out of
Welded steel
How far can water travel before reaching a collection point for a storm sewer?
1000 feet
Manholes are spaced about every
500 feet… And that the ends of lines and at each change in direction
Drainage lines are generally designed with a slope sufficient to allow…
Self – cleaning. This is about 0.3% minimum, developing a flow speed of about 2 ft./s. You don’t want water flowing more than 10 ft./s.
