Intersections: The Axis of Evil

How Roundabouts are a Sustainable Alternative, and When They Make Sense

Evan N. Pratt, PE

All Intelligent Statements by:

Stephen B. Dearing, PE, PTOE

Roadways Are The Most Dangerous

Public Facilities

On The Face Of The Earth

– In the U.S., about 650 PEOPLE DIE each week.

– Same as 3 Plane Crashes…

–EACH WEEK !?!

SOCIAL: National Crash Statistics

All Reported

Intersection

Fatalities

Intersection

Injuries

Intersections

THEREAL AXIS OF EVIL

ALTERNATIVES ANALYSIS

GOAL: TRIPLE BOTTOM LINE

• Social – Improve Safety AND Mobility for all, Delays

• Financial – Construction and Land Cost, Cost of delays

• Environmental – Air pollution, impervious

• THERE IS NO PERFECT ALTERNATIVE!

THE PROBLEM:

Too Many DogsIn Cars

100 Yrs. CONVENTIONAL WISDOM?MORE LANES SHOULD MOVE MORE CARS?

SUSTAINABLE??

WE CAN DO BETTER!!

THESE look fun…

TO PARAPHRASE

“The…problems…we have created cannot be solved using the same thinking we used to create them..”

SO WHAT ARE THE NEW IDEAS?

TYPICAL ROUNDABOUT RETROFIT

CASE STUDY: US-23/THOMPSON RD Roundabouts vs. Traditional

FINANCIAL: Can Save $8,000,000 of OUR $$• Highest value/cost ratio• 75% Less Construction $$, no ROW • Less crashes, Less Delays = Less cost

SOCIAL: (Less Death is always Good)• 90% Reduction in Fatalities & 76% Reduction in Crashes• Pedestrian refuge• Dramatic LOS Improved: A vs. C in 2025 = 30 sec/vehicle

ENVIRONMENTAL: (Breathing is also Good)• Least delay=Less Greenhouse Gasses• Less pavement (not always the case)

0.0

2.0

4.0

6.0

8.0

10.0

TOT INJ PDO

CRASH TYPE

CR

AS

H F

RE

Q.

Before Roundabouts

After Roundabouts

ALTERNATIVES -- SAFETY:Average annual crash frequencies at 11 U.S. intersections

converted to roundabouts

- FHWA Roundabout Guidelines

WHERE TO CONSIDER RAB’s

• Capacity problems

• Safety problems

• ROW or other constraints on more lanes

• Large left turn turning movements

SOCIAL: #1 CONCERN = PEDS•COMPARE TO EXISTING•2 COUNTERINTUITIVE POINTS

SOCIAL: Thwarting the Axis of Evil

Less Conflict Points = LESS DEATH

Environmental and Social Before – Ashley, NC

ENVIRONMENTAL AND SOCIAL After – Ashley, NC

SOCIAL: PEDESTRIANS, THE #1 CONCERN

INNOVATION FOR LARGER RAB’s: THE HAWK SIGNAL

SOCIAL: Driver’s view of Ped Actuated HAWK Signal in West Bloomfield Township

WE CAN DO BETTER!!

$25 to $30 M $12 to $15 M

FINANCIAL-CONSTRUCTION-LAND-TIME

O/M: -SIGNALS-PAVEMENT

Diverging Diamond

QUESTIONS??

Placemaking in a Roundabout by a hospital in

Bahrain