This compilation of videos is mainly multilane roundabouts in various locations and sizes that have large truck accommodation. Note many of the truck drivers choose to take up the whole roadway to prevent side-by-side travel that lane stripes encourage. One or two show the effect of adverse cross-fall on trucks versus the rolled crown design that eases left turns.
- Each has unique considerations for trucks, but all demonstrate the adequacy of roundabouts for most vehicle types.
- Roundabouts, by being circular require turning for all movements regardless of the intended direction, as compared to standard cross intersections where only rights and lefts require a turn.
- In addition, with multilane roundabouts trucker drivers and other drivers must operate their vehicles in close proximity while executing entering and circulating turns. Roundabout designers are responding to the complexity of this driving task in several as I’ll this series of clips shows.
- Wide variety of Users and Design Vehicles
- Context issues of available space, presence of pedestrians, rural and urban, percent trucks and their size RESULT in designs that are not homogenous
- Larger Vehicles = changes in operations with wider geometry
- Designers are becoming more sensitive to: Legal, Safety, ROW, Aprons, Truck Stability
- Stripes need to be evaluated for their effectiveness for trucks. In the U.K. most multilane roundabouts do not have circulatory stripes unless there are exclusive turn lanes on approach.
Vertical design – go with rolled crown versus adverse cross-fall
- Adverse cross-fall influences speed only slightly - Entry deflection dominates circulating speed in the first place
- Adverse crown influences truck stability
- Aprons affect truck ground clearance
- Aprons also affect truck stability
- Aprons influence light vehicle deflection
- Complex interaction with horizontal design
- Curves and cross-slope > g forces
- Stripes on the circulatory roadway require aprons
- No USDOT Minimum Ground Clearance for low-boy trucks but 3 – to - 6 Inch is Common
Oversized load uses truck apron while traveling through a roundabout in Greenwick, New York.
Semi truck uses truck apron while making a left turn at a roundabout.
Trucks turning left, right and going straight through at a roundabout in Wisconsin.
Truck makes right turn at roundabout.
PEI Low Boy driving through a roundabout.
Fuel truck at roundabout in Dismdale, Michigan.
Semi-truck makes U-turn at roundabout.
Wickenburg, Arizona roundabout with trucks passing through.
Armdale Roundabout in Nova Scotia, Canada shows truck passing through.
Roundabout on Happy Valley Road in Arizona shows semi trucks traveling a roundabout too quickly.
Truck overlaps path at roundabout in White Rock, British Columbia.
STH 29 Roundabout
AutoTrack Wind Turbine Tower Truck Example
Roundabouts in Wisconsin with over size over weight vehicle traveling through.
Truck passing through Vail Roundabouts.