Motor Vehicles Real Intersection Design

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Motor VehiclesReal Intersection Design
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Outline

• Sight distance
• Design vehicle
• Alignment profile
• Lanes
• Bike-Ped conflictspoints
• Good Design is

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SIGHT DISTANCE A drivers ability to see ahead
is of the utmost importance in the safe and
efficient operation of a vehicle on a highway.
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Crest Vertical Sight Distance
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Intersection Sight Distance
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Locate XW in Sight Triangle
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Design Vehicle

• Identify design vehicle for each turn
• Multiple design vehicles per turn?
• Speed v. Turns

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Multiple Design Vehicles
WB-50 Semi
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Design Vehicle Table
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Speed v. Turns
WB-50
27 mph
R v2 / 15(ef)94
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Alignment Profile

• Right angles safer than skewed intersections
• 90o Desirable
• 65o Acceptable
• Avoid lt 60o

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Lanes

• 10 12 ft
• Avoid road space that has no clearly defined
  function
• Match approach and departure lane
• Avoid urban recovery lanes
• Avoid through left turn lanes
• Guide drivers clearly

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Sea of Asphalt
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Large, Tight Intersection
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Recovery Lanes
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Through Left Turns
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Bike-Ped Conflicts Points
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Good Design is

• Self-evident
• Self-explaining
• Self-enforcing

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Credits

• William Anderson, Vollmer Associates, NJ,
  wanderso_at_vollmer.com
• Michael Moule, Livable Streets, Tampa FL,
  moule_at_livablestreetsinc.com
• Michael Russo, New Jersey DOT, Mike.Russo_at_dot.stat
  e.nj.us
• Michael King, Traffic Calmer, Brooklyn NY,
  miking_at_trafficcalmer.com