Quad-RoundaboutDouble-Diamond Interchange

ITS World Congress 2011

Joel K. Marcuson, PEUlteig EngineeringFargo, ND, USA

Background

Concept Developed for Design/Build I-494/TH 169 ProjectMinneapolis, MN, USA

3 Traffic Signals Create 3mile Backup Every Morning on TH 169Only Signals on TH 169 Corridor

Project Need

Remove 3 Signals and Old-Fashioned Cloverleaf/Signalized Intersection Design

Replace with Direct Interchange,Bridges/Roundabouts – Local Traffic6 Roundabouts = MOT Opportunity

Project Description

Keep Through Traffic on I-494 and TH169 MovingMaintain Access to Local Traffic Around and Through Project

MOT Objective

Remove Signals QuicklyBuild Bridges Quickly

Run Turning/Local Traffic on Roundabout System

MOT Approach

Existing Conditions - Current

Proposed Plan - Ultimate

MOT Plan – Full Access (Interim)

Using Permanent Features (Roundabouts) for New PurposeAccommodates all Traffic and Movements

Innovation

Innovation Description

Full Access, Improved Traffic EarlyTH 169 Free Flow

I-494 Bottleneck RemovedAvg Speeds Doubled

Unconstrained Flow – During Construction

Benefits of Innovation

Table 1 - Level of Service*, Average Speeds

Stage ExistingAM/PM 1A AM/PM 1B AM/PM 1C AM/PM 2 AM/PM

Avg Speeds(mph) 13/11 15/10 12/8 14/8 27/27

N TH 169 LOS B/C B/C C/C C/C Free**

S TH 169 LOS A/D D/C A/B C/B Free**

Highwood LOS E/F F/F E/F E/F Free**

Benefits of Innovation

Current Need - > Service< System Interchange

Quad-Roundabout DD Interchange Fills That Need

Results of Innovation

Flooding – Closed All Nearby Crossings Except TH 169Volumes Increased on TH 169Restripe 169, Remove Signals

Nature Interfered

$5B DeficitGovernment Shutdown

Contractor Stopped

Politics Interfered

Contractor Lost Time, TwiceLost Money, Twice

New Approach – Build Final QuicklyQuad Roundabout DD Abandoned

Result

One of Best Designs Never ImplementedAn Approach That Will Work

For Right Occasion/ Right Time

Quad-Roundabout DD Interchange

Are EverythingStill Want to Share Idea

Could be Groundbreaking

Timing/Circumstances

Between Service and SystemHigh-Performance Service Interchange

Significant Cost SavingsSignficant Benefits

New Category Needed

System Costs = $250-500MHigh-Performance = $25-50MSimilar Results, 10% of Cost

$$ Impacts Important

Couldn’t Make it “Not” WorkDoubled Traffic – No Appreciable

Change in Performance

What We Discovered

Questions?