RIVERTON CITY ROUNDABOUT TUCKETT & FERGUSON CONSULTING

CE EN 472 – Senior Design

JOSH BELNAP TYSON FERGUSON PETE KELLY ROB NAYLOR BEN TUCKETT WINTER 2012

• Objectives

• Project Site

• Design Concept/Components

• Cost Analysis

• Traffic Analysis

• Summary

• Examine feasibility of a roundabout in Riverton, Utah

• Create a roundabout design to meet future traffic demands

Project Site PROJECT SITE

Design Concept DESIGN CONCEPT

Two Lane vs One Lane With Slip Lane

Safety

• Fewer Collision Points

• No Weaving Movements

Efficiency

• No yielding required on slip-lane

• Fewer cars in roundabout

ADVANTAGES OVER TWO LANE ALTERNATIVE

Signs

1st 2nd 3rd

SIGNING

Other benefits include:

• Fewer Collisions

• Less delay per vehicle

• Less vehicular emissions

Roundabout Signal

Cost of Construction 700,000$ 700,000$

Cost of Maintenance per year 2,000$ 5,000$

Lifetime savings 90,000$ -$

COST ANALYSIS

Objective - Design a roundabout to serve traffic conditions in 2030 at a Level of Service (LOS) C

Assumptions

• 50/50 directional split

• K-factor from 8% to 12%

• 10% heavy-vehicle factor

• 180 pedestrians/hour (Synchro)

• 100 pedestrians/hour (HCM)

• Peak hour factor of 0.92

TRAFFIC ANALYSIS

Results

• A k-factor > 10% causes excessive queuing

• More vehicles on slip lanes decreases overall delay

SYNCHRO

K = 8% K = 12%

Results

• LOS measured by vehicle delay

• Delay increases with more vehicles in the circulatory roadway

• LOS worsens as k-factor increases

• LOS C at k = 0.10

• Additional traffic control devices are recommended if delay exceeds 35 seconds per vehicle

HIGHWAY CAPACITY MANUAL LOS

An effective alternative should future traffic conditions reach LOS F

METERING

SUMMARY

• Reduced delay and maintenance costs compared to signalized alternative

• Safer than traditional two lane roundabout alternative

• User friendly and easy to navigate

• Questions?