TOC Training PT' 2

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TOC Training PT. 2
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Maps

• F\UDOT-TOC\Training\Maps.pptx

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AASHTO Green Book

• Road basics
• Categories of roads
• Freeway traffic flow
• Infrastructure environment
• Intro to geometry

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AASHTO Green Book
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Road Categories

• Primary purposes of roads are to provide movement
  and access. Larger roads are primarily for
  movement. They connect to smaller roads which
  provide access.
• Freeways
• Arterials
• Collector Roads
• Local Roads

More movement Less access More access Less
movement
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Freeways

• Controlled access
• Grade separation (no signals)
• High speeds (55 mph)
• Maximum safety measures
• Highest level of scrutiny in design
• Examples
• I-15
• I-80
• SR201 East of 7200 West

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Arterials

• No grade separation, but limited access
• Can be principal (major) or minor arterials
• Often multiple travel lanes
• Moderate speeds (40-45 mph)
• Examples
• Bangerter Highway
• State Street
• Foothill Blvd.
• 10600 South

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Collectors

• Collect traffic from arterials to service local
  and residential areas
• Can be major or minor collectors
• Compromise of speed and access
• Generally 35-40 mph
• Examples
• 2100 South frontage road

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Local Roads

• Smallest roads in network
• Allow essentially unlimited access
• Low speed (20-25 mph)
• Lowest level of scrutiny in design
• Examples
• Everything else

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Traffic Flow

• Speed, Density, and Flow are the primary
  evaluation criteria
• Flow number of vehicles that pass a given point
  in a given time period
• Flow Density Speed

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Traffic Flow Theory
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Flow Density Speed
Bumper-to-bumper conditions. When density
reaches a maximum (many vehicles), speed 0 so
flow 0
Empty Freeway conditions. Speed is unlimited
since there is no traffic, but since density 0,
flow 0.
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Shockwave

• Backups and queuing on a highway due to a sudden
  reduction of capacity
• Bottlenecking
• Causes
• Reduction of lanes
• Incident
• Construction

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Queue Theory

• Queue line
• Queue is formed when arrivals wait for a service
  or an opportunity.

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Lane Numbering

• Lanes are always numbered from the drivers left
  to right or from the center and working to the
  outside

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Lane Numbering
1
2
3
4
1
2
3
4
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Typical Cross Section
Sidewalk Park Strip Curb Gutter Shoulder Stripin
g Travel Lane(s) Median
Bicycle lanes or parking areas are generally
taken from available space in the shoulder
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Typical Cross Section
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Freeway Elements
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Horizontal Curve

• Designed to provide safe, continuous operation at
  a design speed

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Horizontal Curve

• Designing a curve
• Find safe minimum radius
• Radius is a function of speed, superelevation and
  friction

Radius (R)
Arc Length (L)
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Vertical Curve

• Gradual change between two tangent grades
• Crest
• Sag

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Vertical Curve

• Crest
• Sag

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Stopping Sight Distance

• Sight Distance Breaking Distance
• Sight Distance is the length of the roadway ahead
  that is visible to the driver
• Breaking Distance is the physical distance needed
  to stop a vehicle

Velocity (MPH)
Distance (feet)
Acceleration (feet/sec) Usually 11.2
Grade ()
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Vertical Curve

• Length of the curve is a function of Stopping
  Sight Distance
• For Crest
• For Sag

Algebraic difference of tangents
Stopping Sight Distance (ft)
Velocity (MPH)
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MUTCD

• Signs
• Markings
• Signals
• Temporary Traffic Control
• (Work Zone)

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Signs

• Regulatory Signs
• Warning Signs
• Guide Signs
• Information Signs

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Markings
Dotted Line 3 segments with 9 gaps
Skipped Line 10 segments with 30 gaps
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Signals

• Timing
• Cycle length
• Split
• Offset
• Infrastructure
• Timing plans

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Work Zone

• Temporary Traffic Control
• Specific standards for using signs and markers

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Work Zone
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Standard Drawings

• UDOTs set of codes setting standards for all
  construction done for state roads
• DD 5A
• Entrance and Exit Ramps at Crossroads

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Standard Drawings
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Answers to Questions
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Question 1

• What is the primary difference between Freeways
  and Surface Streets?
• Signals Grade separation vs. no grade separation

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Question 2

• Show the units of flow by expressing it in a
  relationship of speed and density. (hint q u
  k)

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Question 3

• Draw a cross section of a typical freeway and
  label each important element.

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Question 4

• Which curve design is dependent on
  superelevation?
• Horizontal Curve

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Question 5

• Describe the following signs. e.g. purpose,
  color, shape.
• Regulatory The Rules, White, Rectangular
• Warning To warn the driver, Yellow, Diamond
• Guide To help the driver know where they are
  going, Green, Rectangular

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Question 6

• What is the gap between pavement markings on a
  skipped line?
• 30

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Question 7

• What section of the standard drawings would you
  most likely find work zone signing standards?
• Traffic Control

TC-2B in the traffic control section