All About Roundabouts for Planners 111814

8/10/2019 All About Roundabouts for Planners 111814

1/111

Ken Sides, P.E., PTOESam Schwartz Engineering

[email protected]

813-289-7771

November 18, 2014

Allabout Roundaboutsfor Planners
mailto:[email protected]:[email protected]


2/111


3/111

Natural Allies

1. New Urbanists

2. Smart Growth advocates3. Active Living advocates

4. Active Transportation practitioners

5. Complete Street advocates

6. Green Street advocates7. Road Diet practitioners

8. Pedestrians, bicyclists, skaters

9. Older population advocates (AARP)

10. Emergency evacuation officials

11. Environmentalists

12. Public health officials

13. Visionaries

Weve gotgreat

answers!

Ken Sides, PE, PTOE Sam Schwartz Engineering


4/111

Roundabout

Basics

Examples

Planning Perspective

Sam Schwartz Engineering


5/111



6/111



7/111


8/111

In 2009 there were2,210,000 crashes at

conventional intersections

at which 7,043 personslost their lives

at a cost to societyexceeding $42 billion.

$42,000,000,000


9/111

The Federal Highway

Administration says:

" Roundabouts reduce fatalitiesby more than 90% "

and injuries by 76%



10/111

Obsolete rotarybeing replacedwith modern roundabout

Kingston, New York



11/111

Cattolica, Italy



12/111

Cattolica, Italy



13/111

Cattolica, Italy



14/111

Cattolica, Italy


15/111

Cattolica, Italy



16/111

The Ybor Ring Roundabout, Tampa



17/111

Roundabout on Tampa Bay Blvd



18/111

Streets are crowned.

2% slope



19/111

Superelevation

Negative Superelevation



20/111

Roundabout

secrets of low speed Horizontal deflection x 3

Negative superelevation

Vertical feature in central island

Soft elements



21/111

Moderate Speeds Kill Pedestrians

Pedestrian Fatalitiesby Speed

0%20%

40%

60%

80%

100%

20 mph 30 mph 40 mph

Speed of vehicle s triking pedestrian

95%

fatal

50%

fatal

5% fatal

10x more fatal ities

Only 5% survive

40%

80%

8x

Only 20% survive

NHSTA DOT HS 809 021



22/111

The Transportation Network



23/111


24/111

The Transportation Network



25/111

A Transportation Network

Complete Streets Complete Intersections

= Complete Networks

+



26/111

Some Complete Streets Policies

Includes a vision for how and why the community wants to complete itsstreets.

Specifies that the term all users includes pedestrians, bicyclists, andtransit passengers of all ages and abilities.

Encourages street connectivity and aims to create a comprehensive,integrated, connected network for all modes;.

Is adoptable by all agencies to cover all roads.

Appl ies to both new and retrof it projects, including design, planning,

maintenance, and operations, for the entire right-of-way.

Directs the use of the latest and best design criteria and guidelines whilerecognizing the need for flexibility in balancing user needs

Directs that complete streets solutions wil l complement the context of

the community.

= compatible = supports



27/111

Roundabout

secrets of low speed



28/111

32 conflict points High-speed High-angle

High-energy

8 conflict points Low-speed Low-angle

Low-energy

Conflict Points

Credit: Michael Wallwork, PE

3

4

What if we designed anintersection starting with

the notion of havingno Kill Zone ??

( What a concept! )

Kill Zone by Ken Sides, PE


29/111

24 pedestrian/vehicleconflict points

8 pedestrian/vehicleconflict points

Conflict Points: Pedestrian/Vehicle

Credit: Michael Wallwork, PE

2

3

The Acacia opened in


30/111

The Acacia

Roundabout

opened in

December,

2001



31/111


32/111


33/111

Complexity


34/111

Complexity



35/111



36/111

Are Roundabouts Right

for Children?

Ken Sides, PE, PTOE


37/111

Compared to adults, children have:

A narrower visual field

Less ability to isolate sounds and determine the direction ofapproaching traffic by auditory cues

Less ability to judge closing speed.

Children cannot understand complex situations or focus on multiplethoughts at once.

Operating Characteristics

of Children

Children have a desire for constant motion and once in motion, have a

compulsion to complete the motion.

Children are more prone to fearlessness and less able to perceive risk.

Children assume adults will assure their safety; they live in a self-centeredworld where fantasy is mixed with reality.

Ken Sides, PE, PTOE


38/111

Suitability Checklist

Much slower vehicle speeds

Much less exposure:1/3 as many ped/vehicle conflictsPedestrian refuge on splitter islandShorter distance; shorter time

Cross only one lane at time, only one direction at a time

Much less complexity

All these benefits apply to elder peds, too

Are Roundabouts Right for Children?

Ken Sides, PE, PTOE


39/111


40/111

They

brought

bikes

and beverages.


41/111


for Older Users?

Ken Sides, PE, PTOE

USA Population

12.5% 65 and older

16 % Younger than 16

3-5 % Cant, wont, choose not to

- 1/3 of US population not in driving prime


42/111

I. Demographic Trends

Older users are becoming more numerous

The segment of the population aged 65 and older grew

nearly twice as fastas the total population between 1990

and 2000.

The size of the older generation is projected to doubleoverthe next 30 years.

Americans aged 85 and older are the fastest growingpart ofthe population.

By 2020 one in fivepeople will be aged 65 or older.

By 2020, the 85%ile design driverwill be someone aged 65.


43/111


44/111

Diminished visual acuity, the ability to discriminate high-

contrast features

Yellowing of our eyes lensesand increased density,

which makes it harder to see in low light conditions

Diminished contrast sensitivity, which makes it harder to

distinguish an object from its background. Also, persons

over 60 have an increasing risk for developing cataracts

and other conditions that reduce contrast sensitivity.

AASHTO Green Book: An appreciation of driver performanceis essential to proper highway design and operation.

Performance Profile of Older Users

Performance profile of older roadway users

Compared to their younger selves:

Ken Sides, PE, PTOE


45/111

Increased sensitivity to glare, which makes it harder to see in

the presence of oncoming headlights, at night, or in the

presence of sun glare in the daytime. Glare introduces stray

light into the yes; it reduces the contrast of important safety

targets.

Slower dark adaptation, which makes it harder to see targets

when moving from areas of light to dark.

Loss of limb strength, flexibility, sensitivity and range of

motion, needed for tasks such as rapidly shifting the right

foot from the accelerator pedal to the brake pedal or arm

movements to steer around obstacles


Ken Sides, PE, PTOE


46/111

Especially Relevant to Intersections Narrowing of the visual field, which diminishes the ability

to see objects in the periphery, such as signs, signals,

vehicles, pedestrians and cyclists

Restricting of the area of visual attention, whichdiminishes the ability to see potential conflicts in the

periphery and to discriminate relevant from irrelevant

information.

Both abilities are necessary for responding quickly andappropriately to a changing traffic scene. Restrictions inthe area of visual attention can lead to looked but didntsee crashes, where a stimuli can be detected, but cannotbe recognized and understood sufficiently to permit atimely response.


Ken Sides, PE, PTOE


47/111

Especially Relevant to Intersections

Decreased motion sensitivity, which diminishes the ability to

accurately estimate closing speeds and distances and is

needed for judging gaps to safely perform left turns at

conventional cross intersections with oncoming traffic or to

cross an intersecting traffic stream

Decline in selective attention, the ability to filter out less

critical information and continuously re-focus on the most

critical information, such as detecting a lane-use restrictedmessage on an approach to a busy intersection or detecting

a pedestrian crossing while watching oncoming traffic to

locate a safe gap


Ken Sides, PE, PTOE


48/111

Especially relevant to intersections

Decline in divided attention, the ability to perform multiple tasks

simultaneously and process information from multiple sources

Decline in PRT(perception-reaction time), the time required toperceive a situation, evaluate it, decide what response is

appropriate and make a vehicle control action such as steering

or braking. PRT increases disproportionately for older motorists

with increase in complexity of the driving situation.

Decline in working memory, the ability to store, manipulate and

retrieve information for later use while driving

Loss of head, neck and trunk flexibility, needed to rapidly

glance in each direction from which a vehicle conflict might be

expected when approaching an intersection


Ken Sides, PE, PTOE


49/111


50/111


51/111

Benefit Cost Analysis


52/111

Benefit Cost Analysis

Life cycle costs over 20 years

N

PV =At [1/(1+j)t]t=1

Benefit/Cost Ratio = Present Value of benefits

Present Value of costs

Few injuries, no fatalities = huge savings

Average Comprehensive Crash Cost per Injured Person(National Safety Council)

Death

Incapacitating

Injury

Non-incapacitating

Injury

Possible

Injury

No Injury

(PDO)

$3,470,000 $172,000 $44,200 $21,000 $2,000

= 34.5


53/111

The Federal Highway

Administration says:" Roundabouts reduce fatalities

by more than 90% "

and injuries by 76%

How can you justify anintersection design that kills at

10xthe rate of modernroundabouts?


54/111

For the holidays,beach residents planted poinsettias and placed

bows on their roundabout.


55/111


56/111



57/111

Coral Gables, Florida

Upscale projects. Add a classy entrance or center



58/111


59/111


60/111

6,500 pedestrians => 8,000 pedestrians



61/111

Turn lanes steal time...and land. As do through lanes

Downtown Asheville, NC


62/111

A roundabout corridor concept...

...makes many good things possible.

Downtown Ashville, NC

Landscaped

median

Angle parking

OR: Lots of asphalt



63/111


Six lanes to cross


64/111

More green, more beauty downtown, ped friendlyMore parking, more access, more biz-friendly

More

bike-

friendly,

too


One laneto cross

Pedestrian

refuge


65/111



66/111


for Planners?

Ken Sides, PE, PTOE

Creating people-centric spaces Demarcate transitions

Redevelopment

Branding Noise & emissions reductions

Property values


67/111


68/111


69/111

Avon, CO Sam Schwartz Engineering


70/111

Avon, CO Sam Schwartz Engineering


71/111

Avon, CO



72/111

Photo by Ken Sides

Equestrian community near Ft.Lauderdale, FL


73/111

Equestrian community near Ft.Lauderdale, FL Photo by Ken Sides


74/111

Ft Lauderdale Beach, Photos by KenSides

"Musica" at the Music Row Roundabout


75/111

Musica at the Music Row Roundabout

Nashville, TN Corridor


76/111

"Musica" at the Music Row RoundaboutNashville, TN


77/111


78/111

Draper, Utah


79/111



80/111


Intersection Queue Blues


81/111





82/111


Volume Queues Access Customers Investment

$


Downtown Sarasota


83/111

Downtown Sarasota



84/111



85/111

Roundabout Corridors



86/111

Big box retail corridor> access management access management

Documents

All About Roundabouts for Planners 111814