The document discusses considerations for paving concrete roundabouts. It notes that concrete pavement is well-suited for roundabouts due to high traffic volumes and turning movements. Proper jointing is key to control cracking from internal stresses. Different joint layout options are presented, including isolating the circle from approaches and using a "pinwheel" pattern. The document provides examples of recently paved roundabouts in Lincoln, Nebraska and emphasizes designing joints to meet structures at 90 degree angles.

1. Lonnie Burklund, PE, PTOE
Manager, Traffic Engineering
City of Lincoln, NE
Public Works Dept.
mobile: 402-416-1357
E-Mail: lburklund@lincoln.ne.gov
Roundabout Paving

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11. Roundabouts
Better Choice of Intersection Control

12. Roundabouts
 Lincoln is Building More Roundabouts
• 30 – 50% increase in traffic capacity
• 40% reduction in all crash types
• 75% reduction in injury crashes
• 90% reduction in fatal crashes
• 40% reduction in ped crashes
• Reduced Costs (Life Cycle)
Better Choice of Intersection Control

13. Roundabouts
 Lincoln is Building More Roundabouts
• Fewer conflict points (16 vs. 56)
• Speed differential minimized
• Short ped crossings
• No red light running
• No signal equipment
Better Choice of Intersection Control
Conflict Comparison (16 vs 56)

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 Geometric Design - Construction Impacts
• Design Vehicles – Radii, Truck Aprons
• Left-of-Center Approach
• Curbs, Islands, Layout
• Alignment, Joints
“It’s a CURVY World

15. Roundabout Paving
 Concrete Pavement is Good
• High Traffic Areas
• Lots of Turning Movements
• Long Service Life
• Resistance to Deformation
Doesn’t rut or shove
Maintains drainage

16. Roundabout Paving
 Proper Jointing is Key
• Control Natural Transverse & Longitudinal
Cracking from Internal Slab Stresses
• Divide Pavement into Construction Lanes
• Accommodate Slab Movements
• Provide Load Transfer
• Provide Uniform Sealant Reservoir

17. Roundabout Paving
 Roundabout Joints

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 Roundabout Joints

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 Do:
• Match Existing Joints
• Place Joints to Meet
Structures
• Be Mindful of Max
Joint Spacing
• Place Isolation Joints
• Make Field
Adjustments if Needed
• Be Practical
 Avoid:
• Slabs < 2ft wide
• Slabs > 15ft wide
• Angles < 60 deg
• Creating Interior
Corners
• Odd Shapes (keep
square or pie shaped

20. Roundabout Paving
 Joint Layout Design Options
• Isolate Circle from Approaches
Joints in circle radiate from center
Joints on approach are standard (perp)
• Pave Through
Isolate two legs
Joints are standard (perp)
• Pinwheel
Directs motorists to exit, or remain inside

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 Joint Layout Design Options
• Isolate Circle from Approaches

22. Roundabout Paving
 Joint Layout Design Options
• Pave Through

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 Joint Layout Design Options
• Pinwheel

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 Lincoln Roundabouts

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 Lincoln Roundabouts

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 Lincoln Roundabouts

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 Lincoln Roundabouts

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 Lincoln Roundabouts

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 Lincoln Roundabouts

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 Lincoln Roundabouts

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 Key Elements - Concrete Roundabouts
• Choose Joint Layout Philosophy
• Preliminary Joint Layout
• Joints Meet Pavement Edges Near 90 deg
Dogleg joints within 2-3’ of an edge
• Adjust Joints (manholes, inlets, etc.)
Isolation joints
• Consider Construction Phasing
• Allow Further Field Adjustment

32. Roundabout Paving
 Medians / Curbs / Islands
• Truck Apron – stamped concrete
• 4” Integral Curbs (mountable)
• Thickened edges, noses

33. Roundabout Paving
 Medians / Curbs / Islands

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 New Projects – Fringe
 Built Environment
 Single-Lane, Multi-Lane

35. Roundabout Paving
THANK YOU!!