Innovative Designs for Improving Intersection Capacity · Ohio State Route 125/Five Mile Road,...

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INNOVATIVE DESIGNS FOR INNOVATIVE DESIGNS FOR IMPROVING INTERSECTION IMPROVING INTERSECTION

CAPACITYCAPACITYPresented by Presented by

NazirNazir LalaniLalani P.E.P.E.TraffexTraffex Engineers Inc.Engineers [email protected][email protected]

AT GRADE INTERSETIONSAT GRADE INTERSETIONSContinuous Flow Intersections (CFI)Continuous Flow Intersections (CFI)

Parallel Flow IntersectionParallel Flow Intersection

Offset LeftOffset Left--turnsturns

Jug HandlesJug Handles

Median CrossoversMedian Crossovers

Split IntersectionsSplit Intersections

Quadrant ConnectorsQuadrant Connectors

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GRADE SEPARATEDGRADE SEPARATEDSingle Point Interchanges (SPUI)Single Point Interchanges (SPUI)

Tight Urban Diamond Tight Urban Diamond

Diverging DiamondDiverging Diamond

Echelon InterchangeEchelon Interchange

Grade Separated IntersectionsGrade Separated Intersections

Queue Jumping for Transit VehiclesQueue Jumping for Transit Vehicles

AT GRADE INTERSECTIONSAT GRADE INTERSECTIONS

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Continuous Flow Intersections Continuous Flow Intersections

Source: Fehr and Peers, Salt Lake City

LeftLeft--turns/thru movements turns/thru movements move togethermove together

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Source: KOA CorporationSource: KOA Corporation

This design includes crosswalks This design includes crosswalks but very long if timed as single phasebut very long if timed as single phase

Source: Fehr and Peers, Salt Lake City

LeftLeft--turns move across opposing lanes at turns move across opposing lanes at Half signal before the intersectionHalf signal before the intersection

Design is patented: US Design is patented: US 50490005049000

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Left-turns move to far left using a half signalso they can turn with thru- traffic

Half signal

http://www.abmb.com/cfi-testdrive.html

Half signal

CONTINUOUS FLOW CONTINUOUS FLOW INTERSECTIONINTERSECTION

LeftLeft--turns moved to the far left turns moved to the far left

LeftLeft--turns at same time as through movementsturns at same time as through movements

Eight phases reduced to fourEight phases reduced to four

Reduces conflicts at the main intersectionReduces conflicts at the main intersection

Improves capacity by up to 70%Improves capacity by up to 70%

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CONTINUOUS FLOW CONTINUOUS FLOW INTERSECTIONINTERSECTION

Four additional traffic signals needed Four additional traffic signals needed –– one on each one on each approach approach

Access to adjacent properties severely limitedAccess to adjacent properties severely limited

Right of way largerRight of way larger

Pedestrians may need to be grade separatedPedestrians may need to be grade separated

More complex for bicyclists More complex for bicyclists

RightRight--ofof--way impactsway impactsSource: KOA CorporationSource: KOA Corporation

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Locations in USALocations in USABaton Rouge, LouisianaBaton Rouge, Louisiana

Maryland Maryland –– Hwy 210Hwy 210

Ohio State Route 125/Five Mile Road, Hamilton CountyOhio State Route 125/Five Mile Road, Hamilton County

BangerterBangerter Hwy and 3500 South, Salt Lake City AreaHwy and 3500 South, Salt Lake City Area

“Continuous Flow Intersections”: ITE Journal, July 2004

Patent Holders: Francisco D. Patent Holders: Francisco D. MierMier and and BelisarioBelisario H. H. RomoRomo, ,

Baton Rouge, LouisianaBaton Rouge, Louisiana

Congestion Reduced by 40%Congestion Reduced by 40%

Volume thru intersection increased by 10%Volume thru intersection increased by 10%

Crashes reduced by 27%Crashes reduced by 27%

More information at :http://www.abmb.com/cfi-BR.html

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Baton Rouge, Louisiana (2006)

For more info: ABMB Engineering (www.abmb.com)

Four-way example in Mexico

LeftLeft--turns/thru movements turns/thru movements move togethermove together

Opposing traffic!

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Parallel Flow Intersections Parallel Flow Intersections

Source: Urban Transportation MonitorSource: Urban Transportation Monitor

LeftLeft--turns are on this side of the medianturns are on this side of the median

Simulation may be viewed at: Simulation may be viewed at: www.quadranteng.comwww.quadranteng.com

Design is patented: US Design is patented: US 71359897135989

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LeftLeft--turns made ahead of the intersection turns made ahead of the intersection

No left turn movements at the intersectionNo left turn movements at the intersection

Eight phases reduced to fourEight phases reduced to four


Improves capacity by up to 70%Improves capacity by up to 70%

PARALLEL FLOW PARALLEL FLOW INTERSECTIONINTERSECTION

Up to at least additional traffic signals needed Up to at least additional traffic signals needed –– one one on each approach on each approach

Access to adjacent properties severely limitedAccess to adjacent properties severely limited

Right of way largerRight of way larger

Pedestrians crosswalks at intersectionPedestrians crosswalks at intersection

Not as complex for bicyclists Not as complex for bicyclists


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Gregory F. Parsons is the Patent Holder Gregory F. Parsons is the Patent Holder

Article published in the ITE Journal October 2007Article published in the ITE Journal October 2007

Additional information in the Urban Transportation Additional information in the Urban Transportation MonitorMonitor

No known operational intersections to dateNo known operational intersections to date


OFFSET LEFTOFFSET LEFT--TURNSTURNSBest suited for wide mediansBest suited for wide medians

Reduces leftReduces left--turn maneuver travel distanceturn maneuver travel distance

Improves visibility of onImproves visibility of on--coming trafficcoming traffic

Conversion to dual leftConversion to dual left--turns possibleturns possible

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(Michigan Left(Michigan Left--Turns)Turns)

Median Crossover Median Crossover

UU--turns median crossoversturns median crossovers

Source: Signalized Intersection Information GuideFHWA-HRT-04-091

Median CrossoverMedian Crossover RightRight--turn after crossoverturn after crossover

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MICHIGAN LEFTMICHIGAN LEFT--TURNTURN

Requires wide mediansRequires wide medians

Remove leftRemove left--turns from intersectionturns from intersection

Improves capacity and reduces collisions at Improves capacity and reduces collisions at the intersectionthe intersection

Vehicles have to go through intersection twiceVehicles have to go through intersection twice

Example in MichiganExample in Michigan

No left-turns are allowed at the signal

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Capacity Gains from Michigan UCapacity Gains from Michigan U-- Turns v. Dual LeftsTurns v. Dual Lefts

Source: NCHRP Report 420: Impacts of Access Management Techniques.

Super Street Median CrossoverSuper Street Median Crossover

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Super Street Median CrossoverSuper Street Median Crossover


No through movements allowed from side streetNo through movements allowed from side street

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Left turns made as ULeft turns made as U--turnsturns

Signalized leftSignalized left--turns and rightturns and right--turnsturns onlyonly

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Limited movement intersection near RR Xing

PrePre--signal Usignal U--turns turns

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PrePre--signal Usignal U--turnturn

PRESIGNAL UPRESIGNAL U--TURNSTURNSRequires wider mediansRequires wider medians

Remove URemove U--turns from intersectionturns from intersection

Improves capacity and reduces collisionsImproves capacity and reduces collisions

Most effective where heavy UMost effective where heavy U--turns presentturns present

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Pre-signal left-turn

Offset LeftOffset Left--TurnsTurns

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Example in AlbuquerqueExample in Albuquerque

Left-turn lanes

JUG HANDLES JUG HANDLES

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JUGHANDLESJUGHANDLES

Near sideNear side

Far sideFar side

UU--TurnTurn

Indirect leftIndirect left--turnsturns

Forward Forward

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Near SideNear Side


Left-turns taken out of main traffic stream


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Forward near sideForward near side

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Reverse Reverse

Far SideFar Side


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Near side

Far side

ReverseReverse

Route 73 SB

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REVERSEREVERSETraffic circulation more circuitousTraffic circulation more circuitous

Right of way needed for connectorRight of way needed for connector

Removes leftRemoves left--turns from the intersectionturns from the intersection

Merge distance needs to be greater than Merge distance needs to be greater than 500 feet. 500 feet.

UU--Turn Turn

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U-Turn crossover

UU--turn crossoversturn crossovers

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UU--turnturn

UU--turnturn

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New regulatory signs for New regulatory signs for jughandlesjughandles

ALTERNATIVE INTESECTION ALTERNATIVE INTESECTION TREATMENTS TREATMENTS

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Quadrant Roadway Quadrant Roadway

Quadrant roadway intersectionQuadrant roadway intersectionSource: KOA Corporation

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CONNECTOR ROADSCONNECTOR ROADSPedestrian traffic more circuitousPedestrian traffic more circuitous

Significant impact on transit operationsSignificant impact on transit operations


Significant construction impactsSignificant construction impacts

Most often used in conjunction with railroad Most often used in conjunction with railroad crossing improvementscrossing improvements

Split Intersections/Frontage Roads Split Intersections/Frontage Roads

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Split IntersectionSplit IntersectionSource: KOA Corporation

SPLIT INTERSECTIONSPLIT INTERSECTIONSpace between roads should be about 300 to Space between roads should be about 300 to 500 feet500 feet

Minimal impact on peds and transit operationsMinimal impact on peds and transit operations

No impacts to adjacent land usesNo impacts to adjacent land uses


Can be first phase of grade separation projectCan be first phase of grade separation project

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Frontage road alignment shifted to Frontage road alignment shifted to increase spacingincrease spacing

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Variable Lane SignVariable Lane Sign

Variable lane sign allows dual rights Variable lane sign allows dual rights during peak hoursduring peak hours

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Queue Jumping for Transit Vehicles Queue Jumping for Transit Vehicles

Source: Urban Transportation Monitor

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Bus priority lane in the NetherlandsBus priority lane in the Netherlands

QUEUE JUMPINGQUEUE JUMPINGBy pass lane requires additional right of By pass lane requires additional right of wayway

Significant reduction in delay on transit Significant reduction in delay on transit operationsoperations

More complex signal operationsMore complex signal operations

Best suited for short headway servicesBest suited for short headway services

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GRADE SEPARATED GRADE SEPARATED INTERSECTIONS INTERSECTIONS

Viaducts with Connector Roads Viaducts with Connector Roads

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Viaduct with connector roadwayViaduct with connector roadwaySource: KOA Corporation

CONNECTOR ROADSCONNECTOR ROADSPedestrian traffic more circuitousPedestrian traffic more circuitous

Significant impact on transit operationsSignificant impact on transit operations



Most often used in conjunction with railroad Most often used in conjunction with railroad crossing improvementscrossing improvements

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Viaduct with connector roadwaysViaduct with connector roadways

Movements between arterials made Movements between arterials made Via connector roadways Via connector roadways

Elevated LeftElevated Left--turns turns

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Center Turning OverpassCenter Turning OverpassSource: KOA CorporationSource: KOA Corporation


Can be constructed within existing rightCan be constructed within existing right--ofof--wayway

Visual impacts to adjacent land usesVisual impacts to adjacent land uses

Merging movements from the leftMerging movements from the left

Addition ice and snow removal impactsAddition ice and snow removal impacts

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Structure costs significantStructure costs significant

No significant impacts on No significant impacts on pedspeds or transitor transit

Little impacts on access to adjacent land usesLittle impacts on access to adjacent land uses

Construction impacts are minimalConstruction impacts are minimal

INTERCHANGESINTERCHANGES

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Single Point Urban Interchanges Single Point Urban Interchanges

SINGLE POINT URBAN SINGLE POINT URBAN INTERCHANGES (SPUI)INTERCHANGES (SPUI)

One intersection (above freeway better)One intersection (above freeway better)

Signals on overhead gantrySignals on overhead gantry

All turns handled in three movements All turns handled in three movements

More expensive (BIG retaining walls)More expensive (BIG retaining walls)

Reduced right of wayReduced right of way

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Single Point Urban InterchangeSingle Point Urban InterchangeLeft-turns take place under (or over) the main traffic stream


SINGLE POINT URBAN SINGLE POINT URBAN INTERCHANGEINTERCHANGE

Requires the same area as a tight diamondRequires the same area as a tight diamond

Requires longer structureRequires longer structure

Significant impact on pedestrian trafficSignificant impact on pedestrian traffic

Significant impact on transit stop locationsSignificant impact on transit stop locations

Can be confusing to unfamiliar driversCan be confusing to unfamiliar drivers

Freeway underneath is preferred optionFreeway underneath is preferred option

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SPUI with freeway overheadSPUI with freeway overhead

View of SPUI from underneath the freewayView of SPUI from underneath the freeway(limits signal head visibility)(limits signal head visibility)

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SPUI in Phoenix with freeway underneathSPUI in Phoenix with freeway underneath(Preferred Design)(Preferred Design)

One signal processes three movements: Off-ramps/on-ramps/thru traffic

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Tight Urban Diamond InterchangeTight Urban Diamond Interchange(TUDI) (TUDI)

Spread DiamondSource: KOA CorporationSource: KOA Corporation

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Tight Urban Diamond


TIGHT DIAMOND TIGHT DIAMOND INTERCHANGEINTERCHANGE

Reach capacity much sooner than SPUIs because Reach capacity much sooner than SPUIs because of special signal phasingof special signal phasing

Space between ramps about 100 feet vs. 300 feet Space between ramps about 100 feet vs. 300 feet for spread diamondsfor spread diamonds


Can have some impacts on transit operationsCan have some impacts on transit operations

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Diverging Diamond InterchangeDiverging Diamond Interchange(DDI)(DDI)

http://www.oregonite.org/2007D6/paper_review/D9_44_Stanek_paper.pdf

DIVERGING DIAMOND DIVERGING DIAMOND INTERCHANGEINTERCHANGE

Unopposed left TurnsUnopposed left Turns

Closely Spaced IntersectionClosely Spaced Intersection

Separate Over crossingsSeparate Over crossings

Crossover IntersectionsCrossover Intersections

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http://www.tfhrc.gov/safety/pubs/07048/07048.pdf

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http://www.435ddi.com/

I 435.Front Street, MoDOT

Source: Bared J. et al., Source: Bared J. et al., ““ Design and Operational Performance of Double Design and Operational Performance of Double Crossover Intersection and Diverging Diamond InterchangeCrossover Intersection and Diverging Diamond Interchange””

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Video Link: https://www.nysdot.gov/portal/page/portal/regional-offices/region4/projects/590winton/diverging-diam

I 590 and Winton Road, NYDOT

I-40/San Mateo Boulevard Interchange in Albuquerque, NMSource: NMDOTSource: NMDOT

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http://http://www.youtube.com/watch?vwww.youtube.com/watch?v=NANacKPO0Q4=NANacKPO0Q4


21 conflict points v. 45 with TUDI21 conflict points v. 45 with TUDI

Smaller ramp intersections Smaller ramp intersections –– reduced clearance reduced clearance intervalsintervals

Un opposed left turns eliminates need for triple leftsUn opposed left turns eliminates need for triple lefts

Eliminates need for retain wallsEliminates need for retain walls

Better sight distanceBetter sight distance

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Need public education campaign because of Need public education campaign because of unusual configurationunusual configuration

Pedestrians have to cross free flowing ramps Pedestrians have to cross free flowing ramps ––merging may require more than two manes in each merging may require more than two manes in each direction between the rampsdirection between the ramps

More intense level of signing, striping and lightingMore intense level of signing, striping and lighting

Limited accident history availableLimited accident history available

Echelon InterchangeEchelon Interchange

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UNDER

OVER

Left-turns taken out of main traffic stream through grade separation

Source: KOA CorporationSource: KOA CorporationEchelon Interchange

ECHELON INTERCHANGEECHELON INTERCHANGE

Needs wide rightNeeds wide right--ofof--wayway

For heavy turning movement locationsFor heavy turning movement locations

Limits access to adjacent land uses in some Limits access to adjacent land uses in some quadrantsquadrants

Appears confusing but all travel patterns are intuitiveAppears confusing but all travel patterns are intuitive

Construction impacts can be severerConstruction impacts can be severer

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RoundaboutsRoundabouts

ROUNDABOUT ROUNDABOUT INTERCHANGEINTERCHANGE

Shorter StructureShorter Structure

Efficient OperationEfficient Operation

Frontage Road Impacts MinimizedFrontage Road Impacts Minimized

Minimal DelaysMinimal Delays

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Roundabouts at an InterchangeRoundabouts at an Interchange

Roundabouts at an InterchangeRoundabouts at an Interchange

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http://www.teachamerica.com/RAB08/RAB08S9AThibault/index.htmhttp://www.teachamerica.com/RAB08/RAB08S9AThibault/index.htm

PEDESTRIAN ACCESSIBILTY ISSUESPEDESTRIAN ACCESSIBILTY ISSUES

US Access Board Concerns about free flowing intersections such aUS Access Board Concerns about free flowing intersections such as roundaboutss roundabouts

INTERCHANGE COMPARISONINTERCHANGE COMPARISON

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Interchanges Types IncludedInterchanges Types Included

Single Point Diamond (SPUI)Single Point Diamond (SPUI)

Roundabout DiamondRoundabout Diamond


Source: Source: ““Innovative Diamond Interchange Designs: How to Innovative Diamond Interchange Designs: How to Increase CapacityIncrease Capacity”” and Minimize Cost and Minimize Cost –– David David StanekStanek

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When to Consider Innovative When to Consider Innovative InterchangeInterchange

Single Point Diamond (SPUI)Single Point Diamond (SPUI)

High leftHigh left--turn volumes > 300 vph at ramp turn volumes > 300 vph at ramp terminalsterminals

Signal progression on cross street importantSignal progression on cross street important

Adjacent signalize intersections closely Adjacent signalize intersections closely spacedspaced


Roundabout DiamondRoundabout Diamond

Low leftLow left--turn volumes < 300 vph at ramp terminalsturn volumes < 300 vph at ramp terminals

Need to minimize structure wideningNeed to minimize structure widening

Need to accommodate Need to accommodate pedspeds and bikesand bikes

Adjacent signalize intersections closely spacedAdjacent signalize intersections closely spaced

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High leftHigh left--turn volumes > 300 vph at ramp terminalsturn volumes > 300 vph at ramp terminals

Need to minimize structure widening (potentially)Need to minimize structure widening (potentially)

Signal progression on cross street not importantSignal progression on cross street not important

OVERVIEW OF INNOVATIVE OVERVIEW OF INNOVATIVE DESIGNSDESIGNS

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Visit Visit http://attap.umd.edu/UAID.phphttp://attap.umd.edu/UAID.php for an for an excellent overview of alternative designsexcellent overview of alternative designs

REFERENCE LIST FOR SOURCES REFERENCE LIST FOR SOURCES OF INFORMATIONOF INFORMATION

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