ITSO Trans Talk

November 5, 2010

ITSO Trans TalkITSO Trans Talk

Vern Swing, P.E. & Steve Manhart, P.E., PTOE, PTPVern Swing, P.E. & Steve Manhart, P.E., PTOE, PTP

November 5, 2010 -- University of MinnesotaNovember 5, 2010 -- University of Minnesota

DIVERGING DIAMOND INTERCHANGEDIVERGING DIAMOND INTERCHANGE (DDI) DESIGN(DDI) DESIGN

Presentation OutlinePresentation Outline

• Interchange Types• Case Study - Elk Run Interchange• Diverging Diamond Interchange

• Design Characteristics• Advantages• Use in North America

• Questions

Interchange TypesInterchange Types

• Basic Diamond


• Diamond System Interchange


• Full Cloverleaf


• Partial Cloverleaf (Parclo)


• Trumpet


• Directional T


• Single-Point Urban Interchange (SPUI)


• Roundabout


• Large Radius Roundabout


• Diverging Diamond Interchange

Diverging Diamond Interchange (DDI)Diverging Diamond Interchange (DDI)

• Springfield, MO


Diverging Diamond Diverging Diamond Interchange (DDI)Interchange (DDI)

Interchange Conflict PointsInterchange Conflict Points

Intersection Conflict PointsIntersection Conflict Points


• AdvantagesAdvantages• Improved Safety• Operationally More Efficient• Expandability• Can be more cost-effective (especially

when retrofitting an existing diamond interchange to DDI)

Case Study: TH 52Case Study: TH 52

• Elk Run Interchange Project• Interchange Design Project• Estimated Cost: $36 Million Total Project

Cost

Elk Run Interchange ProjectElk Run Interchange Project

• Project Development Area


• Mn/DOT S.P. 2505-48 (TH 52)


• Mn/DOT S.P. 2505-48 (TH 52)

• Interchange Options Considered

• Large Radius Roundabouts• Smaller Radius Roundabouts• Single-Point Interchange• Diverging Diamond Interchange - DDI

(NOTE: FHWA refers to DDI as Double Crossover Diamond – DCD)

DDI Proposed Layout at Elk RunDDI Proposed Layout at Elk Run


Q) Are there headlight concerns, since traffic is

directly in front of each other before the crossovers?

A) No. The direct headlight approach is a further distance

than a common scenario where a left turn lane is directly

opposite the opposing left turn. The headlights do not affect

the crossover movements since vehicles are angled away from

each other at the crossovers. Putting up any type of headlight

shields (also known as glare screens) on the curb is ill-advised

since there will be a in safety due to poor sight distance.

SYNCHRO/SimTraffic Analysis of DDISYNCHRO/SimTraffic Analysis of DDI

Proposed Elk Run DDIProposed Elk Run DDI

• Findings• Mn/DOT proposed diamond interchange

layout reaches maximum capacity at 40% build-out.

• Proposed DDI layout reaches maximum capacity at 79% of build-out.

►DDI Concept was ultimately selected by Mn/DOT.

DDI from the Air – Springfield, MODDI from the Air – Springfield, MO

Driving a DDI – Springfield, MO Driving a DDI – Springfield, MO

Use in North America Use in North America

• I-44 & MO-13, Springfield, MO• I-15 & Main St, American Fork, UT• I-15 & 500 East, American Fork, UT• I-70 & Woods Chapel Rd, Kansas City, MO• I-435 & Front St, Kansas City, MO• Botts Rd & M-150, Kansas City, MO• I-270 & Dorsett Rd, St. Louis Co, MO• Along Baltimore-Washington Pkwy,

Anne Arundel Co, MD• Hwy 427 & Rathburn Rd, Toronto, ON• I-5 & Fern Valley Rd, Phoenix, OR

• New Circle Rd Interchanges, Lexington, KY• I-590 & Winton Rd, Rochester, NY• I-75 & US 224/SR-15, Findlay, OH• I-480 & Tiedman Rd, Brooklyn, OH• Ashford-Dunwoody Rd Interchange,

Atlanta, GA• 8 Interchanges in/around Atlanta, GA• West Catawba/Exit #28, Charlotte, NC• I-95 & Thurbers Ave, Providence, RI• IL-59 & I-88, Naperville, IL• US-129 Bypass / Bessemer St/ Middle-

settlements Rd Interchange in Alcoa, TN

Questions? Questions?

Vern Swing, P.E.Principal Transportation Engineer/PresidentRLK [email protected]

Steve Manhart, P.E., PTOE, PTPSr. Transportation Engineer IIRLK [email protected]

6110 Blue Circle Drive, Suite 100Minnetonka, MN 55343

952-933-0972

www.rlkinc.com

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