roundabout construction: 14th street & superior

Lonnie Burklund, PE, PTOEManager, Traffic Engineering

City of Lincoln, NEPublic Works Dept.

mobile: 402-416-1357 E-Mail: lburklund@lincoln.ne.gov

Roundabout Paving

Roundabouts

Roundabouts

Roundabouts

Roundabouts

Roundabouts

Roundabouts

Roundabouts

Roundabouts

Roundabouts

Roundabouts

Better Choice of Intersection Control

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

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)

Roundabouts

Geometric Design - Construction Impacts• Design Vehicles – Radii, Truck Aprons• Left-of-Center Approach• Curbs, Islands, Layout• Alignment, Joints

“It’s a CURVY World

Roundabout Paving

Concrete Pavement is Good• High Traffic Areas• Lots of Turning Movements• Long Service Life• Resistance to Deformation

Doesn’t rut or shoveMaintains drainage

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

Roundabout Paving

Roundabout Joints

Roundabout Paving

Roundabout Joints

Roundabout Paving

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

Roundabout Paving

Joint Layout Design Options• Isolate Circle from Approaches

Joints in circle radiate from centerJoints on approach are standard (perp)

• Pave ThroughIsolate two legsJoints are standard (perp)

• PinwheelDirects motorists to exit, or remain inside

Roundabout Paving

Joint Layout Design Options• Isolate Circle from Approaches

Roundabout Paving

Joint Layout Design Options• Pave Through

Roundabout Paving

Joint Layout Design Options• Pinwheel

Roundabout Paving

Lincoln Roundabouts

Roundabout Paving

Lincoln Roundabouts

Roundabout Paving

Lincoln Roundabouts

Roundabout Paving

Lincoln Roundabouts

Roundabout Paving

Lincoln Roundabouts

Roundabout Paving

Lincoln Roundabouts

Roundabout Paving

Lincoln Roundabouts

Roundabout Paving

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

Roundabout Paving

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

Roundabout Paving

Medians / Curbs / Islands

Roundabout Paving

New Projects – Fringe

Built Environment

Single-Lane, Multi-Lane

Roundabout Paving

THANK YOU!!