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CC 2019-03-12_06b PP_Informational Presentation by Rick Engineering Regarding RoundaboutsModern Roundabouts Presented By: Nate Stong, PE Rick Engineering Company Sean Houck, PE Kimley-Horn March 12, 2019 2 Introduction to Roundabouts •What is a roundabout •Why they work •Types of roundabouts •Benefits •Examples 3 What is a Roundabout? •Traffic Control •Yield at Entry •Traffic Deflection •Pavement markings and raised islands direct traffic into a one-way counterclockwise flow •Geometrics •The radius of the circular road and the angles of entry are designed to slow the speed of vehicles A Modern Roundabout IS NOT… 600+ feet 120-250 ft For Example… Why They Work 1.Cars entering a roundabout must yield to those already in the circle. 2.Curved geometry results in low speeds. 3.With all cars traveling in the same direction, roundabouts eliminate head on collisions, as well as left turn conflicts, one of the most dangerous moves in an intersection. 4.With no traffic lights to divert drivers’ attention upward, roundabouts keep motorists focused on the cars and pedestrians around them. Types of Roundabouts Source: US Department of Transportation: Federal Highway Administration Types of Roundabouts Source: US Department of Transportation: Federal Highway Administration Safety Benefits –Reduced Conflict Points Safety Benefits -Crash Severity Safety Benefits -Crash Reduction 44%All crashes Fatal/injury crashes 48% 60% Convert two-way stop to roundabout Convert signalized to roundabout Source: 2010 US Department of Transportation: Federal Highway Administration 78% Reduced Delay Roundabouts move traffic through an intersection more quickly, with less congestion on approaching roads. •89% reduction in delays •56% reduction in vehicle stops Source: Mark Doctor, P.E., FHWA Resource Center Source: Washington State DOT Pedestrian and Bicycle Circulation Photo Credit: Carmana & City of Edmunds, WA Pedestrian and Bicycle Circulation Photo Credit: Dan Burden Thank You! Large Vehicle Accommodation •Semi-Trucks •Tractor stays on pavement •Trailer can off-track onto mountable apron •Fire Trucks and Buses •Not required to traverse mountable apron Central Island Landscaping / Art Corridors –Bird Rock Road, La Jolla, CA •20,000 vehicles per day •15% increase in business •Slower vehicle speeds = Increased business exposure •Access Management/fewer left turns = Increased driver comfort and safety •Families feel comfortable walking around = Increased ped traffic •Noise levels reduced, better conversations, less stress School Zones •Slower vehicular speeds •Shorter crossing distances •Reduced number of conflict points •Cross one direction of traffic at a time, with refuge in splitter island Benefit/Cost Analysis Benefits of intersection control are expressed in terms of safety, delay, and emissions Source: FHWA Benefit/Cost Analysis Source: Mark Doctor, P.E., FHWA Resource Center Roundabouts are Good for Older Drivers •Lower speeds through roundabout •Forgiving, mistakes not lethal •Longer decision making time •NO demand to accurately judge closing speeds of fast traffic •Low energy crashes •No wide visual scans •Simple decision-making •By 2020, the 85 percentile design driver will be someone aged 65 or older “By 2025,a quarter of all drivers in the United States will be over the age of 65.Intersections are the single most dangerous traffic environment for drivers of any age with left-hand turns being the single most dangerous traffic maneuver that any of us can make.Forty percent of all crashes that involve drivers over the age of 65 occur at intersections.This is nearly twice the rate of experienced younger drivers . “AARP would like to see more roundabouts constructed because of the many safety benefits that they present for drivers of all ages.” “Older Americans, in particular, are supportive of roundabouts.” -Federal Highway Administration AAA Endorsement AAA Safety Benefits of Highway Infrastructure, May 2017 •Safer Roads Investment Plan identified six categories of countermeasures that collectively will provide nearly 95% of the anticipated crash reductions. •30% of the overall fatality and serious injury reductions could come from intersection improvements. •The intersection improvement with the greatest potential for fatality and serious injury reduction is: CONVERSION OF EXISTING INTERSECTIONS TO ROUNDABOUTS Roundabout Resistance Source: US Department of Transportation: Federal Highway Administration Summary •Safe •Low speed (bicycle speeds) •Eliminate right-angle and head-on conflicts •Reduce vehicle/ped conflict points and exposure time •Efficient •High capacity, low delay •Wide nodes, narrow roads •Complete Streets •Multimodal •Green Streets •lower emissions and noise and opportunity for stormwater quality treatment features •Large Vehicles •Semi-trucks •Fire trucks •Transit buses •Aesthetics •Gateway -community identity •Landscaping & Public Art