diverging diamond interchange · what is a diverging diamond interchange (ddi)? similar to a...
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Diverging Diamond Interchange M-150/Botts Rd Interchange
Kansas City, MO
Presented by:
Patty Hilderbrand PE MPA
Matt Spencer PE MBA
June 26th, 2012
What is a Diverging Diamond Interchange (DDI)?
Similar to a Standard Diamond Interchange
Signals at each end of the interchange
Traffic crosses to opposite sides at signals
Eliminates left-turn signal phasing
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How a Diverging Diamond Interchange (DDI) Works
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Example of a DDI
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Botts Road at M-150
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Botts Road North of M-150
Interchange at Botts Road and M-
150
Botts Road and M-150 Interchange
Existing Conditions
• At-grade
intersection
• Increased
capacity due to
National Security
Campus and
Centerpoint
Development
• Up to 20% truck
traffic predicted
• 2,000 vehicles
during peak hours
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Goals of the Value Engineering Study
Study Goals:
• Select preferred alternative based on the criteria
• Identify design practical solutions
• Identify Green solutions to apply to final
recommendation.
Screening Criteria:
• Traffic operations (60%)
• Constructability (15%)
• Economic issues (15%)
• Environmental issues (10%)
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Value Engineering Workshop
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Standard Diamond Split Diamond
Continuous Flow Diverging Diamond Michigan U-Turns
Box Diamond
Pros & Cons of a DDI
Pros
Left Turning Movements
Smaller Footprint
Reduces Congestion
Two Phase Operation
Construction Cost Savings
Safety Improvement– Reduces Conflict
Points
Cons
High Through Traffic Volumes
Driver Expectation
Off Ramp Traffic Must Turn
Adjacent Intersections
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Challenges of DDIs – Driver Comfort
Line of sight
Glare screens
Transition angle
Lane widths
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Challenges of DDIs
Public Education
• Drivers
• Bike/Ped
Signing
• Location
• Details
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DDI Structure Benefits
Reduced structure length
• MSE walls
Reduced structure width
• Trail location
Simple, short, cost-effective bridge
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Special Features - Walkway
Allows pedestrian
access
Increases driver
comfort
Decreases
structure width
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Sustainable Infrastructure
Dry detention basin
Planted islands and
medians
Variable flow inlets
Hardscape design
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Sustainable Infrastructure
Native plantings
Bio swale
Low ditch grade
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Sustainable Infrastructure
Consultant selection
Non traditional design
Reduced maintenance
Green Scorecard
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Operating DDI
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