ROUNDABOUTS ON THE ROAD TO SUSTAINABILITY

Presented bySteve Nolen

Transportation Solutions, Inc.Redmond, WA

http:/www.tsinw.com425-883-4134

Sustainability

It can be defined and applied in a variety of ways to the planning, construction, maintenance and operation of all modes of transportation.

From consideration of environmental issues in the infrastructure life-cycle cost analysis to carbon footprint assessment in the construction management process, to environmental and social factors being considered in the project design process.

Sustainable Practices

Sustainable practices in public works atr key to satisfying the triple bottom line of social, environmental and economic needs.

As such, it is critical for these practices to be incorporated as part of an agency's good business case in the selection, design and management of transportation facilities.

The State’s GHG Problem

In 2005, transportation generated 47 percent of Washington State’s total atmospheric carbon emissions, in contrast with electricity generation and buildings, which accounted for 20 percent each.

Cars and trucks generated 32.3 million metric tons of atmospheric carbon, which was 73 percent of the transportation carbon emissions, and 34 percent of total emissions.

Washington State’s Response

In 2007, Washington Gov. Chris Gregoire set a goal of reducing the state’s greenhouse gas (GHG) emissions by 10 million tons (11 percent) by 2020.

State population is projected to grow by 20 percent over that time.

The compounding effect of expected population growth and an overall 11 percent GHG reduction is a 25 percent per person GHG reduction.

But that is just the beginning, because the GHG reduction goals ramp up to 50 percent below 1990 levels by 2050.

Sustainability Measures in Transportation Improved by Roundabouts

Environmental Impact

Pollution/Emissions

Greenhouse Gas Emissions

Non-Renewable Energy Reduction

Motor Vehicle Fuel

Operations

Cost Reduction

Right of Way requirements

Construction Cost

Operations Cost

Collision / Injury Reduction

Number

Severity

Roundabouts Reduce Speed and Increase Fluid Traffic Flow

More fluid merging of traffic streams Collisions less frequent / less severe Virtually no time stopped/idling Reduced travel time

Roundabouts in Washington State 2011

Roundabouts are Safer

National Cooperative Highway Research Program (NCHRP) Report 572* indicates roundabouts reduce crashes by 35 percent at intersections where stop signs or signals were previously used for traffic control.

*NCHRP Report 572: Roundabouts in the United States. National Cooperative Highway Research Program, TRB, NAS, Washington DC, 2007.

Roundabouts are Safer

Insurance Institute for Highway Safety - Study of 24 intersections

Roundabouts reduced collisions of all types by 39%, injury collisions by 76%, fatal and incapacitating collisions by 90%.

This is due to the fact that roundabouts force vehicles to travel at slower speeds, and provide fewer conflict points and collision angles for motorists and pedestrians.

Roundabouts reduce delay and improve traffic flow

Contrary to many peoples’ perceptions, roundabouts move

traffic through an intersection faster, with less congestion on approaching

roads.

Roundabouts Eliminate Right Angle Conflicts

Better Flow Equals Less Congestion

Roundabouts promote a continuous flow of traffic.

Unlike intersections with traffic signals, you don’t have to wait for a green light at a roundabout to get through the intersection.

Traffic is not required to stop – only yield – so the intersection can handle more traffic in the same amount of time.

Why are Roundabouts Safer?

Less potential for serious crashes – since vehicles all travel around the center island in the same direction, head-on, left-hand turn, and right-angle collisions are eliminated.

Low travel speeds – because drivers must yield to traffic before entering a roundabout, they naturally slow down. The few collisions that occur in roundabouts are typically minor with few injuries, since they occur at low speeds of 15 – 20 miles per hour.

No red lights to run – roundabouts are designed to keep traffic flowing without requiring vehicles to stop, so the incentive for drivers to speed up to make it through a yellow or red light is removed.

Conversion of Signals to Roundabouts is Sustainable

Significant improvements in traffic flow follow conversion of traditional intersections to roundabouts. (IIHS)

Study of intersections where roundabouts replaced stop signs: 13-23 percent reduction in vehicle delays

Study of intersections where roundabouts replaced traffic signals or stop signs: 89 percent average reduction in vehicle delays 56 percent average reduction in vehicle stops

How much improvement depends on leg volumes and terrain

Economic SustainabilityDo roundabouts save money?

The cost of building a roundabout and a traffic signal is comparable.

A roundabout may need more property within the actual intersection, but takes up less space on the streets approaching the roundabout.

Roundabouts usually require less overall property to build than a signal with turn lanes because traffic doesn’t have to line up and wait for a green light.

Roundabouts eliminate hardware, maintenance and electrical costs associated with traffic signals: approximately $5,000 per year.

However, there are typically more overhead lights and additional maintenance with the central island landscaping or grass mowing at a roundabout.

Roundabouts reduce idling and demand for motor vehicle fuels.

Reduced Fuel ConsumptionAverage driver idles 5-10 minutes a dayIdling 60 minutes = 1 gallon of gasIdling = 45 gallons of gas per year per driver200 million drivers X 45 Gallons = 9 billion gallons per year$4 per gallon gas >>> $36 billion a year

Roundabouts offer significant indirect savings

Environmental Costs

9 billion gal x 9.26kg GHC/gal x 1000 = 83.4 million metric tons GHC

Landscaped areas are opportunity for sustainable storm water management

Time CostReduced time spent behind the wheel

Collision CostsATLANTA, May 11, 2011 (UPI) -- U.S. officials say motor vehicle crash deaths cost the country $41 billion a year in medical and work-loss costs.

Top 5 ReasonsRoundabouts are Sustainable

1. Roundabouts are often less expensive to build and maintain than other intersection control alternatives.

2. Less congestion means less time spend driving, lower fuel cost and less greenhouse gas

3. Increased safety means lower emergency response, health care and other societal costs.

4. Roundabouts do not specifically require periodic maintenance like traffic signals

5. Power outage? No problem! They still work perfectly.

Reason Drivers and Local Officials Should like Roundabouts

No need for Red Light Cameras