A modern roundabout is a circular intersection where traffic flows around a center island.
Today, roundabouts can be alternatives to traffic signals and stop signs to control traffic. In many cases, they have several
advantages over signals and stop signs, including:
Fewer injury crashes and fatalities
Increased pedestrian safety
Less vehicle delay and pollution
Roundabouts, like all intersections, undergo thorough analysis prior to implementation to determine if it is the appropriate solution. MnDOT has more information concerning roundabouts located on their Roundabouts page.
Today, roadways are designed using engineering factors that establish the quantity, type and thickness of material that
needs to be used to balance vehicle loads and roadway use.
Among other factors, current pavement design considers the amount, type and weight of the traffic using the road. This data is used to calculate an ESAL (equivalent single-axle load) factor; this factor is a way of measuring the impact that a vehicle will have on a pavement.
Pavements can be viewed as a "consumable" and are designed to carry an estimated number of ESALs over their design life. As each vehicle passes over a pavement, a portion of its life (the vehicle's ESAL factor) is consumed. Eventually, a pavement's life is expended, and it needs to be reconstructed.
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To Pave or Not to Pave?
Making Informed Decisions on When to Upgrade a Gravel Road
Paved roads provide improvement over gravel in ways that are hard to quantify with dollars, including improved winter surfaces, improved safety from improved signage and delineation, a safer surface with higher skid resistance, a smoother surface that increases user satisfaction and reduces vehicle maintenance costs, redistribution of traffic away from gravel roads, and an increased tax base on adjacent property.
Of the estimated 4 million miles of roads in the United States, nearly half—1.5 million miles—are unpaved.
Unpaved roads serve a valued purpose in our roadway system, but maintenance costs are significant. Paved roadways also are costly to maintain.
Like everything else, maintenance costs for both paved and unpaved roads are rising. We need to optimize those costs to best serve the public. Reduced funding and resources require us to be more efficient spenders of the money we do have. Preparing for future maintenance and upgrades allows us to better manage funds that are available now.
Local Road research Board (LRRB)
Brochure: Local Road Research Board
(PDF)
Supports and shares the latest in research applications with Minnesota City and County Engineers through the funding of research projects
Research Services -- Quality, Decision Driven Research
Research Services strives to find transportation solutions that address our customer needs, align
with department priorities, and produce results in a safer, more efficient, and cost-effective
transportation system.
Our research engineers and administrators help identify research needs, then help manage and evaluate projects throughout their life cycles — from conception to implementation and technology transfer.
Use of Foamed Asphalt with Cold-in-Place Recycling and Full Depth Reclamation
In addition, new hot and cold mix plants and several types of powerful inplace
recycling equipment now are available. Performance-based testing
and mix design methods have improved greatly. More contractors are
familiar with foamed asphalt.
Used with both methods, foamed asphalt helps reduce binder and transportation costs, increases efficiency,
decreases environmental impact, and adds strength and moisture resistance to remaining pavement materials.
