RMAG Consultant Traffic Analysis (Ch.2)

8/9/2019 RMAG Consultant Traffic Analysis (Ch.2)

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Final Report

21

2. RoadwaysThischapterpresentsanddiscussestheresultsofthetrafficanalysiscompletedforthehorizonyear

2030.

The

analyses

continue

from

the

previous

work

performed

for

the

Existing

Conditions

Report.

An

analysisofthegrowthofpopulation,employmentandtravelinthestudywasconductedandisdetailed

inthischapter.TheanalysesexaminethebaselineconditionsofimplementingtherecommendedEIS

mitigationstrategies,aswellaspedestrianimprovements,andthenidentifyadditionalmeasuresto

improvetrafficconditions.Aseriesofroadwayimprovementsarerecommendedandprioritizedfor

implementation.Costestimatesforconstructionarealsoestimated.

VHBpreviouslycompletedananalysisofexistingconditionsinthestudyareaandtheresultswere

presentedintheWiehleAvenue/RestonParkwayStationAccessManagementPlans:ProfileofExistingConditions,datedJune22,2007whichcanbefoundathttp://www.fairfaxcounty.gov/fcdot/pdf/wr_

sam/existing_conditions_june22.pdf.ThisExistingConditionsReportalsopresentedinformation

relativetotheroadwayclassificationoftheroadwayswithintheStudyArea.

CurrenttrafficoperationswereanalyzedusingthesimulationtoolSynchro(version6),withinputfiles

obtainedfromtheVirginiaDepartmentofTransportation(VDOT).Theintersectionmeasuresof

effectiveness(MOEs)suchasLevelofService(LOS)anddelayweresummarizedbyproducingreportsin

theHighwayCapacityManual(HCM)formatthatwereprovidedintheExistingConditionsReport.The

analysishadshownthatmostintersectionsperformataLOSofCorbetterduringtheAMandPM

peakhours.ThereareonlyahandfuloftheintersectionsthatwereexaminedthatperformedatanLOS

ofDorworse.

TheseresultsraisedseveralissueswithrespecttotheapplicationoftheHCMmethodologytoquantify

intersectionMOEs.

This

methodology

examines

each

intersection

in

isolation;

it

does

not

account

for

meteringfromupstreamintersections,nordoesitaccountforintersectionspillbackfromdownstream

intersections.Forexample,theLOSoftheintersectionofRestonParkwayandSunsetHillswas

computedasLOSEintheAMpeakhour;however,theintersectionofRestonPkwyandthewestbound

DIAAHrampsoperateatLOSF,andoftenspillsbackintothisintersection,preventingvehiclesfrom

leavingtheintersectionofRestonPkwy/SunsetHills.Theactualperformanceofthisintersectionis

thereforeworsethanpredictedbytheHCMmethodology,whichdoesnotaccountforqueuespillback.

ThesecondissuethatwasidentifiedintheanalysiswasthatthecountsthatVDOTprovidedwithintheir

Synchrofilesdonotreflectfulldemand.ThecountersthatfedinformationintotheSynchrofilesonly

reflectintersectionthroughput,ratherthandemand,astheintersectioncannotprocesseveryonedue

to

capacity

constraints

or

downstream

intersection

congestion.

Thus,

when

counts

from

oversaturated

conditionsareused,intersectionMOEsreportedbytheHCMmethodologytendtounderstate

congestionlevelsandshowbetteroperatingconditionsthanactualnetworkperformance.

Forthereasonsdescribedabove,thestudyteamappliedamuchmoresophisticatedtrafficoperations

analysissoftwareprogramforfutureconditions:VISSIM.Thisprogramaccountsforqueuespillback

effectsandproducesmoreaccuratemeasuresofsystemoperationalperformance.


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Final Report

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Thissectionsummarizesprojectedlanduseandtraveldemandfor2030.AsshowninFigure12,the

boundariesofthestudyareaincludetheFairfaxCountyParkwaytothewest,HunterMillRoadtothe

east,FoxMillRoadandLawyersRoadtothesouth,andWiehleAvenuetothenorth.Inaddition,a

stationinfluenceareathatreferstotheareaimmediatelysurroundingthetwoproposedstationswas

identifiedas

away

to

focus

on

the

stations

in

the

station

access

management

plans.

a.

TheMetropolitanWashingtonCouncilofGovernments(MWCOG)Round7.0cooperativelanduse

forecastswereusedtocalculatefuture2030traveldemand.Figure21showsthe2030projected

populationaroundtheRestonarea.Everyzonewithinthestudyareawillhavesomelevelofresidential

populationin2030.Figure21showspercentpopulationchangefrom2005to2030inthisarea.The

totalprojectedpopulationinthestudyareain2030isapproximately82,000,whichincreases

approximately28%fromthe2005totalpopulation.Comparedto2005,theareasthatareexpectedto

increasethemostinpopulationby2030includethestationinfluenceareadirectlyadjacenttothe

stationsaswellastheresidentialareasalongRoute28,withmorethan200%growth.

Figure21:2030StudyAreaPopulation


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Final Report

23

Figure23:2030StudyAreaEmploymentProjection

Figure23shows2030projectedemploymentaroundtheRestonarea.Althoughemploymentwillbe

clustered,allzonesinthestudyareawillhavesomelevelofemployment.Figure24showsthepercent

employmentchangefrom2005to2030.Thetotalemploymentinthestudyareain2030is

approximately80,000,anincreaseofapproximately27%overthetotalemploymentin2005.Thetotal

employmentinthestationareain2030isapproximately62,000,alsoanincreaseofapproximately27%

comparedto2005totalemployment.Unlikethepopulationgrowthpattern,thestationarea

experiencesonlymoderateemploymentgrowth,between25%and50%.

Figure22:2005to2030StudyAreaPercentPopulationChange


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Final Report

24

Figure24:2005to2030StudyAreaPercentEmploymentChange

Futuretraveldemand,includingautomobile,busandpedestrianmodes,wasforecastusingtwoprimary

sources:1)theFairfaxCountyregionaltraveldemandmodeland2)outputsoftheNorthernVirginia

MajorInvestmentStudyModel(NVMISM)thatwasusedfortheDullesCorridorRapidTransitEIS.The

FairfaxCountymodelwasusedtoforecastvehiculardemand,notincludingbuses;whileNVMISMmodel

outputswereusedtoforecastbuspassengerandpedestriandemandforaccesstothenewMetrorail

stations.AutomobiledemandfortheplannedparkandridestructureattheWiehleStationwas

forecastindependently

of

the

two

models

based

on

the

assumption

that

this

structure

would

be

operatingatcapacityby2030.

TheFairfaxCountymodelisamodifiedversionoftheMWCOGregionaltraveldemandmodel,witha

moredetailedzonesystemwithinFairfaxCounty.TwosetsofrefinedmodelswereprovidedtoVHBfor

thisstudy:1)year2000wasusedasabaseyearand2)year2030ConstrainedLongRangePlan(CLRP)

networkmodelwasusedasthefuturescenario.ThemodelingperiodsincludedtheAMpeakperiod

from6AMto9AMandthePMpeakperiodfrom4PMto7PM.

Asubareamodelingtechniquewasemployedforboththestudyareaandstationinfluenceareain

ordertofocusonthetripsintheareaofinterest,asopposedtothewholeregion.Thetravelforecasting

resultsfordifferentscenarioswereevaluatedbasedonthefollowingthreetriptypes:

InternaltoInternal(II):IItripsarethosetripswhichstartandendinsidethestudyarea.

ExternaltoInternal(XI)orInternaltoExternal(IX):XItripsarethosetripsthatstartoutside

thestudyareaandendinsidethestudyarea.IXtripsarethosetripsthatstartinsidethestudy

areaandendoutsidethestudyarea.

ExternaltoExternal(XX):XXtripsarethosetripsthatstartandendoutsidethestudyarea.

Theyarealsocalledthroughtrips.


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Final Report

25

Figure25showsacomparisonoftotalstudyareatripsbetween2000and2030fortheAMpeakperiod.

Overall,thesplitofthethreetriptypesin2030remainsalmostthesameasthebaseyearsplit.Total

tripsin2030areprojectedtobe128,867,whichis34%greaterthanthe95,848totaltripsin2000.II

tripsincreasethemostofthethreetypeswith55%growth.

Figure26showsacomparisonoftotaltripsinthestudyareabetween2000and2030forthePMpeak

period.

Overall,total

trips

in

the

PM

peak

period

are

approximately

55%

greater

than

AM

peak

period

tripsinboth2000and2030.Thesplitofthreetriptypesin2030changesslightlyfromthebaseyear

split.WhiletheXIorIXtripsplitremainsalmostunchanged,23%oftripswouldbeshiftedfromXX

tripstoIItripsin2030.Thereare199,415totaltripsin2030,whichis33%greaterthanthe149,470

totaltripsin2000.IItripsincreasethemostwithgrowthof55%overthe30yearperiod,asintheAM

peakperiod.

0

50,000

100,000

150,000

200,000

250,000

2000 2030

II XIorIX XX

43%

12%

46%

42%

11%

46%

Figure25:ComparisonofStudyAreaAMPeakPeriodTotalTrips

Year 2000 Year 2030 %Growth

I-I 10,129 15,651 55%

I-X or X-I 44,170 59,633 35%

X-X 41,549 53,583 29%

Total 95,848 128,867 34%

IIareinternaltointernaltrips IXareinternaltoexternaltrips

XIareexternaltointernaltrips XXareexternaltoexternalorthroughtrips


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Final Report

26

Figure27showsacomparisonoftotaltripsinthestationinfluenceareain2000and2030fortheAM

peakperiod.Incontrasttotravelpatternsinthestudyarea,thesplitofthethreetriptypesin2030

changesfromthebaseyearsplit.34%oftripswouldbeshiftedfromXXtripstoIItripsin2030.There

are87,379totaltripsin2030,whichis32%greaterthanthe66,039totaltripsin2000.IItripsincrease

themostwith227%growth.

0

50,000

100,000

150,000

200,000

250,000

2000 2030

II XIorIX XX

41%

14%

48%

38%

12%

47%


I-I 17,708 27,417 55%

I-X or X-I 70,457 95,591 36%

X-X 61,305 76,407 25%

Total 149,470 199,415 33%

Figure26:ComparisonofStudyAreaPMPeakPeriodTotalTrips




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Final Report

27

Figure28showsacomparisonoftotaltripsinthestationinfluenceareabetween2000and2030forthe

PMpeakperiod.Overall,totaltripsinthePMpeakperiodareapproximately45%greaterthanAMpeak

periodtripsinboth2000and2030.Thesplitofthethreetriptypesin2030allchangefromthebase

yearsplit.BoththeXIorIXtripsplitandIItripsplitwouldincreaseby3%whiletheXXtripsplit

woulddropby6%in2030.Thereare125,888totaltripsin2030,whichis31%greaterthanthe96,064

totaltrips

in

2000.

IItrips

increase

the

most

with

211%

growth.

Theimpactoftheproposedstationsismoreprominentinthestationinfluencearea.Moretripswould

begeneratedwithoriginsand/ordestinationsthatareinsidetheinfluencearea.


I-I 948 3,100 227%

I-X or X-I 17,008 23,929 41%

X-X 48,083 60,350 26%

Total 66,039 87,379 32%

0

50,000

100,000

150,000

200,000

250,000

2000 2030

II XIorIX XX

73%

4%

27%

69%

1%

26%

Figure27:ComparisonofStationInfluenceAreaAMPeakPeriodTotalTrips




8/33

Final Report

28

TheDIAAHhasalargenumberoftripsthatpassthroughtheRestonareawithoutleavingthefacility.

Table21showsDIAAHthroughtripsforthestudyareaandstationinfluenceareain2000and2030.

ThevolumeoftripsduringtheAMpeakperiodin2030isprojectedtobe26%33%greaterthanthe

volumeoftripsin2000,whilethecorrespondinggrowthisprojectedtobe4%9%forthePMpeak

period.OneinterestingfindingisthattherearefewerfutureyearAMpeakperiodtripsthanPMpeak

periodtripsinthebaseyear.Thisindicatesthatdemandiscurrentlyapproachingorexceedingroadway

capacityontheDIAAHduringthePMpeakperiod,butnotduringtheAMpeakperiod.

Table21:DIAAHThroughTrips

Year2000 Year2030 %Growth

StudyArea AMPeakPeriod 15,085 19,055 26%

PMPeakPeriod 21,716 22,481 4%

Station

InfluenceArea

AMPeakperiod 15,865 21,054 33%

PMPeakPeriod 23,295 25,492 9%


I-I 1,898 5,902 211%

I-X or X-I 25,801 37,925 47%

X-X 68,365 82,061 20%

Total 96,064 125,888 31%

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

2000 2030

II XIorIX XX

71%

5%

30%

65%

2%

27%

Figure28:ComparisonofStationInfluenceAreaPMPeakPeriodTotalTrips




9/33

Final Report

29

ExcludingtheseDIAAHthroughtrips,studyareaandstationinfluenceareatripsforbothAMandPM

peakperiodswerecomparedbetween2000and2030(seeTable22andTable23).SincetheDIAAH

tripswerecountedasXXtrips,thetripsfortheothertwotriptypesremainunchanged.Figure29and

Figure210showthetriptypeproportionsexcludingDIAAHthroughtripsforthestudyareaand

stationinfluencearea,respectively.TheextractionofDIAAHtripsresultsinanincreaseinthe

proportionofIItripsandtheproportionofXIorIXtrips,andareductionintheproportionofXXtrips

whencomparedtotheproportionswhenDIAAHthroughtripsareincluded.Inthestudyarea,the

proportionofII,XIandIXtripswilldropby2%from2000to2030fortheAMpeakperiodwhilethe

proportionwilldecreaseby1%forthePMpeakperiod.Inthestationinfluencearea,theproportionof

II,XIandIXtripswilldropby3%from2000to2030fortheAMpeakperiod,whiletheproportionwill

alsodecreaseby3%forPMpeakperiod.Thisrepresentsareductioninstudyandinfluencearea

throughtripsassociatedwithregionalroadwaysinthefuture,whichindicatesthatthegrowthinlocally

orientedtripsisdisplacingregionalthroughtripdemand.

Table22:ComparisonofStudyAreaTripsExcludingDIAAHThroughTrips


AM

Peak

Period

II 10,129 15,651 55%

I

X

or

X

I

44,170 59,633 35%XX 26,464 34,528 30%

Total 80,763 109,812 36%

PMPeak

Period

II 17,708 27,417 55%

IXorXI 70,457 95,591 36%

XX 39,589 53,926 36%

Total 127,754 176,934 38%

Table23:ComparisonofStationInfluenceAreaTripsExcludingDIAAHThroughTrips


AMPeak

Period

II 948 3,100 227%

I

X

or

X

I

17,008 23,929 41%XX 32,218 39,296 22%

Total 50,174 66,325 32%

PMPeak

Period

II 1,898 5,902 211%

IXorXI 25,801 37,925 47%

XX 45,070 56,569 26%

Total 72,769 100,396 38%


10/33

Final Report

30

Figure29:StudyAreaTripPurposeSplitExcludingDIAAHThroughTrips

12%14% 14% 15%

55%55% 54%

54%

33%31% 32% 31%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2000AMPeakPeriod 2000PMPeakPeriod 2030AMPeakPeriod 2030PMPeakPeriod

II XIorIX XX

Figure210:StationInfluenceAreaTripPurposeSplitExcludingDIAAHThroughTrips

2% 3%5% 6%

34%35%

36%38%

64%62%

59%56%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2000AMPeakPeriod 2000PMPeakPeriod 2030AMPeakPeriod 2030PMPeakPeriod

II XIorIX XX




11/33

Final Report

31

Future2030trafficprojectionsweredevelopedfortheAMandPMpeakperiods,asopposedtoonlythe

AMandPMpeakhours.Thisisduetothefactthatsincethepeakhoursareprojectedtobeheavily

congested,whichwillforcethepeakdemandtospreadoutsideofthepeakhours.Whenthisoccurs,

theevaluationofpotentialroadwayimprovementsshouldfocusonmeasuresthataddressdemandover

peakperiods.

The

VISSIM

simulation

model

allowed

for

this

type

of

extended

period

analysis.

Itisalsoimportanttonotethatthe2030trafficprojectionsusedforthisstudymaintainedconsistency

with2030trafficprojectionsdevelopedinapreviousstudyoftheareaaroundtheWiehleStation3.

Figure211andFigure212presenttheAMPeakPeriodandthePMPeakPeriodvolumes,respectively,

thatwereusedfortheanalyses.

Figure211:AM3hourPeakPeriodRoadwayLinkVolumeswithintheStationInfluenceArea(2030)

3DullesCorridorMetrorailProject,TrafficOperationalAnalysisPhase2,CambridgeSystematics,Inc.,March12,2007.


12/33

Final Report

32

Figure212:PM3hourPeakPeriodRoadwayLinkVolumeswithintheStationInfluenceArea(2030)

Forthe2030analysis,asetofroadwaycapacityadditions(roadwayactions)wereincludedwiththe

baselineassumptions,andthenadditionalimprovementswereincludedunderamorerobustsystem.

ThebaselineroadwaycapacityadditionsaretheactionsthatwereidentifiedintheDullesRailFEISas

appropriatemitigationmeasures.

Thereisaneedtobalancetheroadwayimprovementswithimprovementsforothermodes,toreflect

thefactthataccesstothestationswillneedtofocusontransitandpedestrianmodes,aswellas

vehicularmodes.Infact,theRestonMetrorailAccessGroup(RMAG)thathelpedguidethisstudy

identifiedpedestrian,bicycleandtransitaccessasprioritiesoverautomobileaccess.Forexample,

wideningaroadwayfrom4to6laneswillimproveroadcapacityandtheabilitytoprocessmore

vehicles;however,thistypeofimprovementcouldpotentiallyhinderpedestrianmovements,especially

atlargerintersections,asitincreasesthecrossingdistanceforpedestrians.

Therearethreegroupingsofroadwayactionsthatwereanalyzedfor2030conditions:1)thoseactions

forroadwaysthatprovideimmediateMetroaccess,2)generalroadwayactionsand3)robustactions

thatwould

be

intended

to

mitigate

congestion

on

along

term

scale,

including

proposed

connectors

over

theDIAAH.

Theactionsdiscussedinthissectionwillprovideincreasedcapacityintheimmediatevicinityofthe

Metrorailstationsonroadwaysthatprovidedirectaccessintothestations.Theseactionsinclude:

1. NewsignalandturnlanesonSunsetHillsRoadforaccessintotheproposedRestonParkway

Metrorailstation.


13/33

Final Report

33

2. NewleftturnlaneforwestboundleftturningmovementattheintersectionofSunsetHills

Road/IsaacNewtonSquareW,whichwouldreplacethesharedleftthroughlanebyprovidinga

dedicatedturnlane.

3. Additional(second)leftturnlanefornorthboundtrafficattheintersectionofWiehleAvenue

andthestationentrance(betweenSunsetHillsRoadandtheDIAAH)andprovideasecond

inboundlane.

TheseroadwayactionswouldimprovedirectvehicularaccessintothetwoproposedMetrorailstations

byprovidingincreasedturningcapacity.Thiscouldreducethepotentialfortrafficvolumesthatexceed

theturnbaycapacityandblockthethroughlanesduringperiodsofhighdemand.

InadditiontotheactionsfordirectaccesstotheMetrorailstations,otherroadwayactionswould

increaseintersectioncapacity,therebyimprovingoperationalperformanceandreducingdelay.These

actionscanrangefromsimplyaddingaturnbayatanintersectiontowideningaroadwaytoprovide

extrathroughlanes.Theactionsanalyzedinthiscategoryinclude:

4. AddanadditionalleftturnlaneontheeastboundDIAAHofframpatWiehleAvenue.

5. Improvethe

right

turn

lane

for

the

eastbound

Sunset

Hills

Road

at

Wiehle

Avenue.

6. ImprovetherightturnlaneforthewestboundSunriseValleyDriveatWiehleAvenue.

7. AddanorthboundthroughlaneonRestonParkwayatSunriseValleyDrive,continuingthislane

totherampforeastboundonramptotheDIAAH.

8. ImprovetherightturnlaneforsouthboundRestonParkwayatSunriseValleyDrive.

TheseactionsarepartoftheEISmitigationprojectslistedintheamendedrecordofdecision.Some

additionalroadwayactionshavebeenidentifiedbeyondtheEISrecommendationsthatareidentifiedin

thefollowingsection.

Thebaseline

traffic

analysis

identified

the

need

for

additional

roadway

capacity

along

Wiehle

Avenue,

as

wellasadditionalconnectionsbetweenSunsetHillsRoadandSunriseValleyDrive.Additionalprojects

weredevelopedthatwouldhelpalleviatetheseissues.Theseimprovements,consideredforthe

robustanalysis,include:

9. AddasecondrightturnlaneonthenorthboundWiehleAvenueapproachatSunsetHillsRoad.

10. AddasecondrightturnlaneonthesouthboundWiehleAvenueapproachatSunriseValley

Drive.

11. AddanadditionalleftturnlaneontheeastboundSunriseValleyDriveapproachatWiehle

Avenue.

12. ProvidetwonewconnectionsovertheDIAAHtoprovidenewlinkstoconnectSunsetHillsRoad

andSunriseValleyDrive:

i. Connectionbetween

Town

Center

Parkway

and

Edmund

Halley

Drive.

ii. ConnectionbetweenSoapstoneDriveandIsaacNewtonSquareW.

Thetrafficsoftwareusedforthe2030analysiswasVISSIM,amicrosimulationprogram.Theadvantage

ofusingsuchaprogramisthatitpermitsanalysisofroadwaynetworksthatareoversaturated(i.e.,

congested)andaccountsforqueuespillbacksaffectingupstreamintersectionsandreductionof


14/33

Final Report

34

throughput.TheVISSIMsoftware,bymicrosimulatingthenetwork,isabletodeterminethe

intersectionthroughputonalocationbylocationbasisincongestedconditions.Macroscopicprograms

suchastheHighwayCapacityManualSoftware(HCS)andSynchrocanonlyanalyzeintersectionsinan

isolatedfashion;theydonotaccountforqueuespillbackfromdownstreamintersections.

Theanalysisbeganbyexaminingbaselineconditions,whichincludetheEISimprovements,andincluded

pedestrianimprovements.Basedontheanalysisofthebaselineconditions,additionalroadwayactions

weredevelopedtoimprovevehicularflow.

TheBaselineAlternativeincludedtheroadwayimprovementsindentifiedaboveandshowninFigure

213.(Thenumbersinthefigurecorrespondtothenumberedprojectslistedonpages1920.)In

additiontothoseroadwayactions,pedestrianimprovementsidentifiedbythePedestrianBikeTeam

(anddetailedinChapter3)werealsoincorporated.Theseactionsimprovethecrossingconditionsat

manyintersectionsforpedestriansbyaddingpedestriancrosswalks,pedestriansignalsand/or

pedestrianrefugeislandsthatshortenthecrossingdistance.Bicyclelanes(whilerecommendedin

Chapter5forsomelocations)werenotincludedfortheroadwayanalysis,theprimarypurposeofwhich

wasto

evaluate

intersection

roadway

actions,

including

the

effects

due

to

pedestrians.

Inordertoassesstheabilityoftheroadwaysystemtohandletheforecasteddemand,aVolumeto

Capacity(V/C)calculationwascompletedforthecordonpointstotheStationInfluenceArea(shownin

Figure214).Thisprocesscomparedthedemandforthelinkversustheroadwaycapacityofthatlink.

TheV/CcalculationswereperformedonapeakhourandpeakperiodbasisforboththeAMandPM

peaksandarepresentedinTable24.Theassumedroadwaycapacitiesatthecordonpointsweretaken

fromtheFairfaxCountytraveldemandmodelandthevolumesarethoseusedintheVISSIMmodel.

Fi ure 213: Locations of Roadwa Actions for Baseline Conditions


15/33

FinalReport

35

Table2

4:2030VolumetoCapacityRatioatCordonPointsforthe

DetailedStudyAreaforAM

andPM

Pea

ksBaselineAlternative

CordonPoint

Location

Direction

Volume

Capa

city

V/C

Volume

Capacity

V/C

Volume

Capacity

V/C

Volume

Capacity

V/C

In

2,6

60

2,8

00

0.9

5

6,6

50

8,4

00

0

.79

1,8

02

2,8

00

0.6

4

4,87

0

8,4

00

0.5

8

Out

1,2

15

2,3

00

0.5

3

3,0

38

6,9

00

0

.44

2,4

80

2,3

00

1.0

8

6,70

3

6,9

00

0.9

7

In

760

1,1

50

0.6

6

1,9

00

3,4

50

0

.55

930

1,1

50

0.8

1

2,51

4

3,4

50

0.7

3

Out

1,2

60

2,8

00

0.4

5

3,1

50

8,4

00

0

.38

821

2,8

00

0.2

9

2,21

9

8,4

00

0.2

6

In

2,4

74

3,8

25

0.6

5

6,1

85

11,4

75

0

.54

2,1

64

3,8

25

0.5

7

5,84

9

11,4

75

0.5

1

Out

2,0

28

4,8

00

0.4

2

5,0

70

14,4

00

0

.35

3,2

99

4,8

00

0.6

9

8,91

6

14,4

00

0.6

2

In

625

850

0.7

4

1,5

63

2,5

50

0

.61

619

850

0.7

3

1,67

3

2,5

50

0.6

6

Out

617

850

0.7

3

1,5

43

2,5

50

0

.60

681

850

0.8

0

1,84

1

2,5

50

0.7

2

In

132

7,0

00

0.0

2

330

21,0

00

0

.02

431

7,0

00

0.0

6

1,16

5

21,0

00

0.0

6

Out

407

7,0

00

0.0

6

1,0

18

21,0

00

0

.05

127

7,0

00

0.0

2

343

21,0

00

0.0

2

In

2,7

15

3,1

50

0.8

6

6,7

88

9,4

50

0

.72

2,4

34

3,1

50

0.7

7

6,57

8

9,4

50

0.7

0

Out

2,0

01

3,7

00

0.5

4

5,0

03

11,1

00

0

.45

2,3

24

3,7

00

0.6

3

6,28

1

11,1

00

0.5

7

In

641

2,4

00

0.2

7

1,6

03

7,2

00

0

.22

1,3

80

2,4

00

0.5

8

3,73

0

7,2

00

0.5

2

Out

2,2

16

2,4

00

0.9

2

5,5

40

7,2

00

0

.77

819

2,4

00

0.3

4

2,21

4

7,2

00

0.3

1

In

2,1

79

1,5

50

1.4

1

5,4

48

4,6

50

1

.17

1,6

33

1,5

50

1.0

5

4,41

4

4,6

50

0.9

5

Out

2,0

83

3,2

00

0.6

5

5,2

08

9,6

00

0

.54

1,6

03

3,2

00

0.5

0

4,33

2

9,6

00

0.4

5

In

952

1,1

50

0.8

3

2,3

80

3,4

50

0

.69

1,3

55

1,1

50

1.1

8

3,66

2

3,4

50

1.0

6

Out

191

3,1

00

0.0

6

478

9,3

00

0

.05

1,0

92

3,1

00

0.3

5

2,95

1

9,3

00

0.3

2

In

890

1,7

00

0.5

2

2,2

25

5,1

00

0

.44

461

1,7

00

0.2

7

1,24

6

5,1

00

0.2

4

Out

271

1,7

00

0.1

6

678

5,1

00

0

.13

883

1,7

00

0.5

2

2,38

6

5,1

00

0.4

7

In

1,2

14

1,7

00

0.7

1

3,0

35

5,1

00

0

.60

841

1,7

00

0.4

9

2,27

3

5,1

00

0.4

5

Out

628

2,8

00

0.2

2

1,5

70

8,4

00

0

.19

1,4

47

2,8

00

0.5

2

3,91

1

8,4

00

0.4

7

In

2,5

12

3,1

50

0.8

0

6,2

80

9,4

50

0

.66

1,9

39

3,1

50

0.6

2

5,24

1

9,4

50

0.5

5

Out

1,2

24

3,1

50

0.3

9

3,0

60

9,4

50

0

.32

3,3

72

3,1

50

1.0

7

9,11

4

9,4

50

0.9

6

In

413

850

0.4

9

1,0

33

2,5

50

0

.40

1,1

94

850

1.4

0

3,22

7

2,5

50

1.2

7

Out

870

850

1.0

2

2,1

75

2,5

50

0

.85

521

850

0.6

1

1,40

8

2,5

50

0.5

5

In

920

1,7

00

0.5

4

2,3

00

5,1

00

0

.45

1,3

43

1,7

00

0.7

9

3,63

0

5,1

00

0.7

1

Out

2,1

50

2,8

00

0.7

7

5,3

75

8,4

00

0

.64

630

2,8

00

0.2

3

1,70

3

8,4

00

0.2

0

AMPeakHour

AMPeakPeriod

PMPeakHour

P

MPeakPeriod

1

SunsetHillsRdw

estofTown

CenterPkwy

2

TownCenter

Pkwy

northofSunset

HillsRd

3

RestonPkwy

northofSunset

HillsRd

4

OldRestonAve

northofSunset

HillsRd

5

SalliemaeDr

northofSunset

HillsRd

6

WiehleAve

northofSunset

HillsRd

7

SunsetHillsRdea

stofMichael

FarradayDr

8

SunriseValley

Drive

eastofWiehle

Ave

9

SoapstoneDr

so

uthofSunrise

ValleyDr

10

ColtsNeckRd

so

uthofSunrise

ValleyDr

11

SouthLakesDr

eastofReston

Pkwy

14

SunriseValley

Drive

w

estofReston

Pkwy

12

RestonPkwy

southofSouth

LakesDr

13

SouthLakesDr

w

estofReston

Pkwy


16/33

Final Report

36

BasedontheV/Ccalculations,thedemandvolumesformostofthecordonpointsdonotexceedthe

capacityoftheroadwaylinks.Afewpointsdoexceedcapacity,butmarginally.V/Ccalculationswere

performedonboththepeakhourandthepeakperiodbecausethevolume(orthedemand)isnot

constantacrosseachofthethreehoursinthepeakperiod;ratherthepeakhourvolumeishigherthan

eitheroftheshoulderhours.Inseveralcases,thevolumeexceedsthecapacityduringthepeakhour,

butnotduringthepeakperiod.Thus,itcanbeexpectedthathighercongestionlevelswilloccurduring

thepeakhourwithlowerlevelsofcongestioninthehoursbeforeandafterthepeakhour.This

illustrates

the

fact

that

the

cordon

points

themselves

are

not

the

constraining

factor

of

the

system.

Thus,virtuallyallofthedemandcanenterandexittheStationInfluenceAreas;however,congestionat

thekeyintersectionswithintheStationInfluenceAreawillactasaconstrainttotrafficmobility.

Figure215andFigure216presentthedistributionofvehicletripstoandfromtheWiehleAvenue

StationintheAMPeakPeriod(3hours)andfromtheWiehleAvenueStationinthePMPeakPeriod(3

hours).Approximately50percentoftripsareto/fromthenorthoftheDIAAH,35percentareto/from

thesouthoftheDIAAHand15percentofthetripsareto/fromtheDIAAH.

Figure214:DetailedStudyAreaCordonPoints


17/33

Final Report

37

Source:VHB(2007)

Source:VHB(2007)

TheanalysiswasconductedusingtheVISSIMmodelforthepeakperiods,atotalofthreehours,to

examinehowtheroadwaynetworkoperatesintheshoulderhoursbeforeandafterthepeakhour.The

keymeasureofeffectivenessthatwasusedwasvehicularthroughputatsevenkeyintersections.This

givesameasureofhowwellthedemandisbeingservedbythebaselineroadwaynetwork.Table25

andTable26presentAMandPMpeakperiodthroughputsummariesatsevenkeylocationswithinthe

stationinfluencearea.

WiehleAvenue

MetrorailStation

ToSoutheast:10%ToSouthwest:24%

ToNorthwest:29%ToNortheast:22%

ToEastonDulles

TollRoad:6%

ToWestonDulles

TollRoad:9%

WiehleAvenue

MetrorailStation

FromSoutheast:

10%

From

Southwest:

24%

FromNorthwest:30%FromNortheast:20%

FromEastonDulles

TollRoad:6%

FromWestonDulles

TollRoad:10%

Figure215:DistributionofIngressTripstotheWiehleAvenueMetrorailStation

Figure216:DistributionofEgressTripsfromtheWiehleAvenueMetrorailStation


18/33

Final Report

38

Table25:AMPeakPeriodThroughputSummaryatKeyIntersectionsBaselineAlternative(2030)

Intersection EBTotal WBTotal NBTotal SBTotal

Intersection

Total

Approach

TownCenterPkwy/SunsetHillsRd

AMPkPdThroughput 4,868 1,776 1,873 8,517

AMPk

Pd

Demand

6,650

2,940

1,900

11,490

AMPkPdThroughput% 73.2% 60.4% 98.6% 74.1%

RestonPkwy/SunsetHillsRd

AMPkPdThroughput 3,907 1,226 3,916 1,770 10,819

AMPkPdDemand 4,925 3,175 8,710 6,190 23,000

AMPkPdThroughput% 79.3% 38.6% 45.0% 28.6% 47.0%

IsaacNewtonSquare/SunsetHillsRd

AMPkPdThroughput 3,892 3,801 770 549 9,012

AMPkPdDemand 4,030 5,810 755 555 11,150


WiehleAve/SunsetHillsRd


AMPkPdDemand 3,065 2,025 11,060 6,790 22,940

AMPk

Pd

Throughput

%

98.4%

102.6%

54.2%

65.9%

67.9%

WiehleAve/SunriseValleyDr


AMPkPdDemand 6,645 5,475 5,085 17,205


SoapstoneDr/SunriseValleyDr

AMPkPdThroughput 2,141 1,604 1,788 140 5,673

AMPkPdDemand 4,555 3,875 2,370 150 10,950


RestonPkwy/SunriseValleyDr

AMPkPdThroughput 742 1,584 5,171 3,433 10,930

AMPkPdDemand 2,300 3,400 6,880 8,138 20,718


OverallThroughput 70,045

OverallDemand 117,453

AMPeakPdThroughputas%ofDemand 59.6%

Note: PeakperiodtrafficdemandprojectionswerebasedonMWCOGCooperativeForecastsofJobsandHousingand

developedusingtheFairfaxCountyTravelDemandModel.Peakperiodthroughputestimatesweredevelopedusing

theVISSIMtrafficsimulationmodel.


19/33

Final Report

39

Table26:PMPeakPeriodThroughputSummaryatKeyIntersectionsBaselineAlternative(2030)


Intersection

Total

Approach


AMPkPdThroughput 1,369 1,716 816 3,901

AMPk

Pd

Demand

4,870

5,715

2,515

13,100




AMPkPdDemand 4,945 8,680 8,690 5,850 28,165



AMPkPdThroughput 635 904 624 1,081 3,244

AMPkPdDemand 5,235 3,725 2,305 1,440 12,705




AMPkPdDemand 6,240 4,600 6,465 6,580 23,885

AMPk

Pd

Throughput

%

12.5%

22.2%

35.5%

19.6%

22.6%



AMPkPdDemand 3,700 4,410 7,245 15,355




AMPkPdDemand 3,105 5,885 850 985 10,825




AMPkPdDemand 3,630 4,055 5,230 9,291 22,206




PMPeakPdThroughputas%ofDemand 30.6%




Forbothpeakperiods,theinternalroadwaynetworkiscongested.Anumberofintersectionscannot

processthedemand,whichcausesqueuespillbacktoadjacentupstreamintersections.FortheAMpeak

period,60%ofthedemandwouldbeservedmeaningthatofallthevehiclesthatwouldliketodrive

throughthekeyintersectionsduringtheAMpeakperiod,only60%ofthosewillbeableto.Congestion

ofthistypewillleadtochangesintravelbehavior;atleastfourresponsesarelikely:

Changetimeoftravel,inwhichthepeakperiodwillextendbeyondthetraditional3hours.

Changepathoftravel,throughtripswillfindotherroutestoavoidthearea.

Changemodeoftravel,sometravelerswillchoosetousetransitorwalk/bike.

Notmakethetripatall.

ForthePMpeakperiod,43%ofthedemandisserved.Thiswouldcauseanevenlongerlengtheningof

thepeakperiodcomparedtothedemandoftheAMpeakperiod.


20/33

Final Report

40

ThefindingsofbothmodelsarethatprojectedtrafficdemandfortheWiehleAvenuecorridoristhe

causeofmuchoftheforecastcongestionanddelayinthestationinfluencearea.Thereareseveral

componentsofprojectedtrafficalongWiehleAvenue:externaltrips,externalinternaltripsandinternal

trips.CriticalsectionsofWiehleAvenueinclude:

1. SouthboundsegmentofWiehlebetweenSunsetHillsRoadandtheDIAAH.

2. IntersectionofWiehleatSunriseValleyDrive

3. IntersectionofWiehleatSunsetHillsRoad

Thefirstbottleneckwillcausecongestionspillovertoadjacentintersectionswithinthestationinfluence

area,includingextendingthequeuesovertoRestonParkway,whichaffectsnorthsouthtravelonthat

arterial.Thelattertwolocationsarelikelytohaveheavycongestion,dueinparttotheproblemscaused

bytheformer.CongestionalongRestonParkwayisprojectedtobeatalowerlevelthanWiehle

Avenue.

TheheavytrafficcomingoutoftheWiehlemetrostationduringthePMpeakperiodwillcauseweaving

conditionsbetweenalltravellanesonthesouthboundsegmentofWiehleAvenuebetweenSunsetHills

RoadandtheDIAAH,astheycomeoutofthemetrostation.Mostvehiclesarenotdestinedtothewest,

sothey

must

weave

over

at

least

one

lane.

If

avehicle

is

destined

to

the

eastbound

DIAAH

ramp,

they

mustweaveacross4lanestoenterintotheturnbays.Itisonly320feetfromtheWiehlemetrostation

accesstotheintersectionwiththewestboundramps,andafurther500feettotheintersectionforthe

eastboundramps.Thisweavingcausesturbidityasvehiclesforcetheirwayoverbetweenthetravel

lanestoreachthelanetheydesiretoreachtheirdestination.Mostvehiclesthatturnrightwhenthey

exittheWiehleAvenuemetrostationentrancewilllikelybedestinedtoSunriseValleyDriveandpoints

southandthuswouldhavetoweaveacrossatleastonelane.Figure217illustratesthisweaving

phenomenon.

Conflictpoint

Note:hollowarrowsillustratethelanesthatarepartoftheturnbayatthenextsignalbeyondthisintersection

Theother

bottlenecks

along

Wiehle

Avenue

are

at

the

intersections

with

Sunset

Hills

Road

and

Sunrise

ValleyDrive.Thelackofturnlanesforthesignificantmovementsaddstothedelaysatthese

intersections.

ThecurrentroadwaynetworkprovidesfortwocrossingsoftheDIAAH;traffictravelingwithinthearea,

toandfromtherailstations;andenteringandleavingtheDIAAHallwillcompeteforthesameroad

spaceonWiehleAvenueandRestonParkway.Providingalternativeroutingpaths,suchasnew

Figure217:IllustrationofWeavingonWiehleAvenuewithMetroEgress


21/33

Final Report

41

connectorsovertheDIAAH,wouldpermitinternaltripsandsometraffictoandfromtherailstationsto

avoidbothRestonParkwayandWiehleAvenue.

A

series

of

roadway

actions,

beyond

those

recommended

in

the

EIS

and

assumed

for

the

future

baseline

analysis,weredevelopedtoaddressthebottlenecksalongWiehleAvenue.Theseimprovementswould

increaseintersectioncapacityandprovidealternateroutingchoicesforvehicles.Connectorsacrossthe

DIAAHwouldprovidenorthsouthalternativestothecongestedRestonParkwayandWiehleAvenue.

Intersectionmodifications,suchasaddingturnlanescanalsoreducetrafficdelayatintersections.The

roadwayactionsthatcouldbeconsideredtoreduceforecastdelayatbottlenecksonWiehleAvenueand

RestonParkwayareillustratedinFigure218andinclude:

9. AddasecondrightturnlaneforthenorthboundWiehleAvenueapproachatSunsetHillsRoad.

10. AddasecondrightturnlaneforthesouthboundWiehleAvenueapproachatSunriseValley

Drive.

11. AddanadditionalleftturnlanefortheeastboundSunriseValleyDriveapproachatWiehle

Avenue.

12. Providingtwo

new

connections

over

the

DIAAH

to

provide

new

links

to

connect

the

major

east

westroadways:SunsetHillsRoadandSunriseValleyDrive:

i. ConnectionbetweenTownCenterParkwayandEdmundHalleyDrive

ii. ConnectionbetweenSoapstoneDriveandIsaacNewtonSquare

Theproposedconnectorswoulddivertvehiclesfromthemajornorthsouthroadwayswithinthestation

influencearea.TheseconnectorswouldbegradeseparatedfacilitiesfromtheDIAAHandwouldnot

includerampsto/fromtheDIAAHasexemplifiedbytheMonroeStreetconnectortothewest,which

passesovertheDIAAHwithoutarampconnection.Forexample,atripfromSoapstoneDrivetothe

WiehleMetrorailStationcoulduseoneoftheseconnectorsandavoidthetrafficonSunriseValleyDrive

andWiehleAvenue,byaccessingtheStationdirectly.ThepotentialfortripsdivertingfromReston

Parkwayand

Wiehle

Avenue

were

estimated

manually

and

assigned

on

the

new

routes.

Figure

219

presentstheestimatednumberoftripsexpectedtomakethisdiversionduringtheAMandPMpeak

periods.ItshouldbenotedthattheFairfaxCountyParkwayliesoutsidethestationinfluencearea,so

therecouldbepotentialfortripdiversionfromthatfacilitytotheTownCenterParkwayandEdmund

HalleyDriveconnector.


22/33

Final Report

42

Figure218:LocationsofRoadwayActionsassumedfortheRobustAlternative

Figure219:EstimatedTripDiversionduetoProposedConnectors(2030)

Note:AM(PM)volumespresentedherearepeakperiod(3hour)volume)

TheactionsincorporatedintherobustconceptwereaddedtothebaselineroadwaynetworkinVISSIM,

andthetripswerereassigned.TheactionsareprojectedtohaveagreatereffectinthePMpeakperiod,

asthecombinedthroughputatthesevenkeyintersectionsisprojectedtoincreasebyapproximately


23/33

Final Report

43

36%comparedtothebaseline.Theincreasewouldbealmost10%intheAMpeakperiod.Table27

andTable28presentAMandPMPeakperiodthroughputsummariesforthesevenkeyintersections.

Table27:AMPeakPeriodThroughputSummaryatKeyIntersectionsRobustAlternative(2030)

Intersection

EBTotal

WB

Total

NB

Total

SB

Total

Intersection

Total

Approach


AMPkPdThroughput 5,677 2,029 163 1,814 9,683

AMPkPdDemand 6,650 2,890 150 1,905 11,595




AMPkPdDemand 4,690 3,175 8,565 6,190 22,620




AMPkPdDemand 4,015 4,875 1,680 555 11,125




AMPkPdDemand 2,870 2,025 10,130 6,790 21,815




AMPkPdDemand 5,390 5,480 4,790 15,660


SoapstoneDr

/Sunrise

Valley

Dr

AMPkPdThroughput 4,177 1,337 2,033 426 7,973

AMPkPdDemand 4,555 3,595 2,365 430 10,945




AMPkPdDemand 2,150 3,400 6,875 7,801 20,226




AMPeakPdThroughputas%ofDemand 67.3%





24/33

Final Report

44

Table28:PMPeakPeriodThroughputSummaryatKeyIntersectionsRobustAlternative(2030)


Intersection

Total

Approach



AMPk

Pd

Demand

4,865

5,700

365

2,515

13,445




AMPkPdDemand 5,095 8,673 8,320 5,850 27,938




AMPkPdDemand 5,245 3,325 2,595 1,445 12,610




AMPkPdDemand 5,265 4,595 6,040 6,580 22,480

AMPk

Pd

Throughput

%

22.3%

29.6%

69.0%

34.2%

39.8%



AMPkPdDemand 3,175 4,415 5,730 13,320



AMPkPdThroughput 2,706 1,934 867 1,819 7,326

AMPkPdDemand 3,090 4,365 850 2,430 10,735




AMPkPdDemand 3270 4055 5230 9080 21635

AM

Pk

Pd

Throughput

%

34.6%

37.0%

61.8%

36.5%

42.4%



PMPeakPdThroughputas%ofDemand 42.8%




TheactionthatwouldhavethegreatesteffectintheincreaseofthroughputfortheAMpeakperiodis

thenewSoapstoneDrivetoIsaacNewtonSquareWconnector.Thisconnectorwoulddiverttripsaway

fromWiehleAvenue,includingthosevehiclesthatwouldotherwiseresultinheavyvolumesofleft

turningvehiclesintotheMetroStationaccesspoints.Thisconnectoralsoreducestheamountoftraffic

exitingfrom

the

proposed

Wiehle

Avenue

Metrorail

Station

onto

Wiehle

Avenue,

thereby

reducing

the

demandaswellasreducingthevolumeoftrafficthatisweavingfromtheMetroaccessandtheDIAAH

ramps.Thisconnectorwouldproviderelieftothecongestionthatwouldotherwiselikelybefoundon

WiehleAvenue.

TheproposedSoapstoneConnectoralsoplaysakeyroleasanadditiontothebusnetworkinRestonby

providingdirectaccessacrosstheDIAAHandtothestationwithoutrequiringtravelonWiehleAvenue.

Inordertoensurethatthisdirectaccessisavailabletotransitvehicles,dedicatedbuslanesshouldbe


25/33

Final Report

45

includedaspartofthisfacility.Asproposed,thefacilitywouldincludepedestrianfacilitiesandtwo

travellanesineachdirection:oneforgeneraltrafficandonededicatedlaneforusebybicyclistsand

buses.ThisconnectioncouldsignificantlyspeedbusoperationsintoandaroundtheWiehleAvenue

stationandshouldbeconsideredindetailasredevelopmentaroundtheWiehleAvenuestationoccurs.

EvenwiththeSoapstoneConnectorinplace,theforecastssuggestthatheavycongestionalongWiehle

Avenuewillcontinuetoexist.Toreducethiscongestionandresultingdelay,itwouldbenecessaryto

furtherwidenroadways,ortoencouragealargershifttononautomobilemodes.Anaggressive

programofTravelDemandManagement(TDM)willhelptoencouragethemodalshiftthatwillbe

necessarytoreducetrafficcongestioninthestationareas.

Theotheractionslistedabovedoimproveoperationsofthekeyintersections,thoughtheseactions

wouldprovideonlymarginalbenefit.Additionaltestingwascompletedtoseeifanyofthespecific

actionswerenotrequired.Forexample,additionaltestingshowedthataddingasecondsouthbound

rightturnlanefromWiehleAvenuetowestboundSunriseValleyDriveactionwouldnotresultina

significantbenefittotrafficoperations,butwouldmakepedestriantravelmoredifficultatthis

intersection.

Theanalysishasillustratedthattrafficspeedsintheareawillbesignificantlyslowerinthefutureas

trafficgrowthcontinuesinthearea.Carsandbusesbothwillhavetotravelinthesametraffic,andbus

speedsareexpectedtobesignificantlyslowerin2030thantheyarein2007.Withoutdedicatedlanes,

bustraveltimewillbenobetterthanSOVandtherewillbealowerprobabilityofpromotingthedesired

shiftfromSOVintobuses.Thishastheeffectofrequiringmorevehiclesandmoredriverstooperatea

recommendedlevelofservice,increasingthecostofthesystem.Onealternativethatcouldrelieve

someoftheincreaseinoperatingcosts,driverstaffandfleetrequirementswouldbetoimplementbus

onlylanesthatallowforfreeflowtrafficconditionsfortransitvehicles.Theselanescouldbeusedonly

duringpeak

hours

and

would

function

as

traditional

travel

lanes

during

the

off

peak

periods.

These

laneswouldhavethedualbenefitsofincreasingbusspeeds(andinturnsignificantlydecreasingthe

operationalcostsandthenumberofnewvehiclesrequired)whilesimultaneouslyattractingmore

passengerstothetransitsystemandawayfromtheircars,thusalleviatingtrafficcongestion.

Theroadsexpectedtohavetheworstcongestionproblemsin2030areWiehleAvenueandReston

Parkway.Buslanesontheseroads,andpotentiallyatmajorintersectionswiththeseroads(likeSunset

HillsandWiehleAve)wouldprobablyhavethemostbeneficialeffectsfortransitriders.Acarefulstudy

oftheimplicationsofbuslanesontheseroadsshouldbeundertakentodetermineifthissolutionwould

benefittheresidentsofReston.Implementationofbuslanesintheimmediatevicinityofeitherofthe

stationsalongtheseroadwayswouldpresentmanychallengesinrightofwayacquisition,operations

andenforcementandwouldrequirethereconstructionandexpansionofthebridgesacrosstheDIAAH.

However,therearelocationsinRestonwherebuslanesmightbebothpossibleandbeneficial.Sunset

HillsRdisincludedasasixlanefacilityintheFairfaxCountyTransportationPlan,andthisexpansionis

includedintheFairfaxCountyComprehensiveLongRangePlan(CLRP).Theroadwayexpansioncouldbe

completedbyconstructingtheadditionallanesaspeakhourdedicatedbusfacilitiesbetween(atleast)

OldRestonAvenueandWiehleAvenue.Thesefacilitieswouldprovideacongestionfreeeastwest

routeintheheartofRestonfortransitvehicles.Significantrightofwayacquisitionandconstruction


26/33

Final Report

46

costswouldbeassociatedwiththisproject,howeveradetailedstudywouldbenecessaryinorderto

determinetheexactquantitativebenefitsofthebuslanes.

The

transportation

network

around

the

Wiehle

Avenue

station

is

comprised

primarily

of

major

thoroughfares(i.e.WiehleAvenue,SunsetHillsRoadandSunriseValleyDrive)andmuchsmallerstreets

anddrivewaysthatprovideaccesstoindividualbuildingsanddevelopments.Becauseofthis,most

vehiclestravelingintheareamustuseoneofthemajorcongestedroutesorintersections.The

potentialexiststodevelopadditionalroadwayconnectionsasawayforlocaltraveltoavoidthemore

congestedmajorroadways.

Muchoftheinfrastructurethatwouldbenecessarytodevelopthisinternalgridofstreetsalreadyexists

intheformofsmallaccessroadanddriveways.Someoftheseexistingfacilitiescouldbeexpanded

alongwithintersectionimprovementsattheaccesspointstoeasetrafficcongestionandvehicledelays.

Theseconnectorstreetswouldhavetheaddedbenefitofprovidingmoredirectconnectionto

pedestriansandbicyclists,asubjectthatwillbediscussedfurtherinChapter4.

ThepreviouslydiscussedSoapstoneConnectorwouldprovideadditionalconnectionsthroughtheback

doortotheWiehleAvenuestation.ExtendingthisroadwayacrossSunsetHillsRoadontoIsaacNewton

SquareWprovidesfurtherconnections.Likewise,IsaacNewtonSquareS/RogerBaconDrcanprovide

aneastwestconnectionnorthofSunsetHillsRd.Otherprivatedrivewaysinthestationareacouldalso

beupgradedtocarrylocalthroughtraffic.

TheanalysesoftheBaselineandRobustAlternativesprovidedinsightintotheroadwayactions

neededtohandletheprojecteddemand.TheactionsidentifiedfortheBaselineroadwayshouldallbe

implemented,andaselectfewfromtheRobustAlternativeshouldalsobeincluded.Thelistingof

recommendedprojects,

illustrated

on

Figure

220,

is

as

follows:

A. NewsignalandturnlanesonSunsetHillsRoadforaccessintotheproposedRestonParkway

Metrorailstation

B. NewleftturnlaneforwestboundleftturningmovementattheintersectionofSunsetHills

Road/IsaacNewtonSquareW,thiswouldreplacethesharedleftthroughlanebyprovidinga

dedicatedturnlane.

C. AddasecondleftturnlanefornorthboundtrafficattheintersectionofWiehleAvenueand

MetroAccess(betweenSunsetHillsRoadandtheDIAAH)andprovideasecondinboundlane

D. AddanadditionalleftturnlaneontheeastboundDIAAHofframpatWiehleAvenue

E. ImprovetheexistingrightturnlanefortheeastboundSunsetHillRoadlegatWiehleAvenue

F. Improvethe

existing

right

turn

lane

for

the

westbound

Sunrise

Valley

Drive

approach

at

Wiehle

Avenueleg

G. AddnorthboundthroughlanefortheRestonParkwayatSunriseValleyDrive,continuingthe

lanetotherampforeastboundDIAAH

H. ImprovetherightturnlaneforthesouthboundRestonParkwaylegatSunriseValleyDrive

I. ProvideanewconnectionovertheDIAAHtoconnectthemajoreastwestroadways:Sunset

HillsRoadandSunriseValleyDrive.TheconnectionwouldbebetweenSoapstoneDriveand

IsaacNewtonSquareWandwouldincludeonesharedbus/bikelaneineachdirection.


27/33

Final Report

47

J. ExpandSunsetHillsRoadbetweenWiehleAvenueandOldRestonAvenuetosixlanes.

Additionallaneswillbeoperatedasdedicatedbuslanesinpeakperiods.

Figure220:LocationsofRecommendedRoadwayActions

Actions9,10,11and12(i),previouslyidentifiedfortheRobustAlternative,arenotrecommended.

Theseprojectswereasfollows:

9. AddingasecondrightturnlaneforthenorthboundWiehleAvenueatSunsetHillsRoad.

10. AddingasecondrightturnlaneforthesouthboundWiehleAvenuelegatSunriseValleyDrive.

11. Addan

additional

left

turn

lane

for

the

eastbound

Sunrise

Valley

Drive

leg

at

Wiehle

Avenue.

12. (i)ProvidingaconnectionbetweenSunsetHillsRoadandSunriseValleyDriveviaTownCenter

ParkwayandEdmundHalleyDrive.

Itshouldbenotedthatevenwithimplementationofalltheroadwayactions,thepeakperioddemand

forboththeAMandPMperiodscannotbeservedwithinthethreehourpeakperiod.Lengtheningof

thepeakperiodshouldbeexpected.

Thenorthsouththoroughfaresareheavilytravelled,buttheeastwestroutesareasimportantto

overallmobilityinthearea.Currently,bothSunriseValleyDriveandSunsetHillsRoadareconsidered

minorarterialsaccordingtotheFairfaxCountyComprehensiveTransportationPlan.Thenumbersof

laneson

both

facilities

vary

depending

on

location.

For

the

most

part,

Sunrise

Valley

Drive

is

a4lane

facility,exceptnearHunterMillRoad,whereitisa2laneroadway.SunsetHillsRoadvariesbetween2

to6lanesdependingonthesection.Themajorfactorofimpedancetoeastwestmobilityistheconflict

forgreentimewithnorthsoutharterialslikeFairfaxCountyParkway,RestonParkwayandWiehle

Avenue.Thesenorthsoutharterialscarrymoretrafficthantheformer.Ifgreentimewereincreased

fortheeastwestarterialswheretheycrossthemajornorthsoutharterials,thenitwouldcomeatthe

expenseofnorthsouthmobility.


28/33

Final Report

48

Theothermeanstoimproveeastwestmobilityinthisareaistoprovidemoretravellaneseastwest.

However,thereislimitedpotentialtoimplementthisoptionduetotherightofwayconstraintsthat

existatsomesegmentsalongtheroadway.TheCountysComprehensiveTransportationPlanshows

SunsetHillsRoadasacomplete6lanefacilityfromFairfaxCountyParkwaytoWiehleAvenue,anda4

lanefacilitytoHunterMillRoad.ThelatterwouldlikelyrequireimprovementstoHunterMillRoadat

theDIAAHinterchange.Thiswouldimprovetrafficoperations,butwouldnotbeabletosatisfythe

demandforthisfacility.TherearenotcurrentlyanyplanstowidenSunriseValleyDrive,howeverthe

additionofpeakperioddedicatedbuslanesisrecommendedasalongtermsolutiontocongestion.

IntersectionimprovementsalongthisSunriseValleyDrive,suchasaddingorlengtheningturnbays,

wouldprovidemorestoragetoaccommodateturningtrafficthatwouldnotblockthethroughlanes.

AnotherprojectthatcouldoccurontheedgeoftheStudyAreaisatrafficcalmingprojectonHunterMill

Road.TheHunterMillRoadTrafficCalmingStudy,astudyconductedbytheNorthernVirginiaRegional

Commission,offersanumberofinnovativeapproachestoimprovesafetyalongHunterMillRoad,

provideforthehighvolumeoftraffic,allthewhileimprovingthelevelofservice.Thereportoutlines

"contextsensitivesolutions"suchasroundaboutsandsplitterislandsatacostlowerthanorequalto

traditionalexpansionofhighways.

Othermeansofimprovingcirculationwithinthestationinfluenceareawouldbetoimproveprivate

parcelaccess(ingressandegress)drivewaysbycombiningtheseaccesspointsatlocationswith

signalizedintersections.Byprovidingseparateturnlanesfortheleftturnandrightturnmovementon

thesedriveways,ratherthanasinglelane,itwouldreducethenecessarygreentimefortheminorlegs,

whichinturnprovidesformoregreentimeforthemainthoroughfare.Anexamplewouldbethenorth

legofIsaacNewtonSquareWattheintersectionwithSunsetHillsRoad.

Finally,itisrecommendedthatasredevelopmentoccursintheWiehlestationarea,localstreet

connectorsbeprovidedasawayforlocaltraveltoavoidthemorecongestedmajorroadways.Four

connectorsofthistypearerecommendedtohelpcreateaninternalgridofstreetsaroundtheWiehle

Avenue

station

as

illustrated

in

Figure

2

21.

The

four

connectors

include:

K. IsaacNewtonSquareWestfromIsaacNewtonSquareSouthtothestationasanextension

oftheproposedSoapstoneConnector.

L. TheStationEntrance(alreadyplannedforimprovementsaspartofstationconstruction)

shouldbeextendedacrossWiehleAvenuetothePrivateDrivewayasfareastasSamuel

MorseDr.

M. MichaelFaradayCourtextensionfromthenewroadwaydescribedin(L)northtothe

extendedRogerBaconDrdescribedin(N)

N. Extension/improvementstoIsaacNewtonSquareSouthfromIsaacNewtonSquareWestto

WildlifeCenterDrive.

Itmaybepossibletoconstructorexpandseveralofthesenewconnectorsaspartofthedevelopment

processas

the

area

surrounding

the

Wiehle

Avenue

station

redevelops.

Proffers

and

other

development

toolscanbeusedtominimizetheexpensetotheCountyofthesefacilities.Dependingonthescaleand

patternofredevelopmentinthearea,thesectionsofcompletelynewroadwaythatwouldconnectto

WildlifeCenterDrivemaystillrequireasignificantCountyinvestment.


29/33

Final Report

49

AstheStudyAreacontinuestogrow,actionstotheroadwaynetworkwillbeneededtohelp

accommodatetheprojectedgrowth.Thefourteen(14)roadwayactionsidentifiedintheprevious

sectionarerecommended,aswellasthepedestrianimprovementsindentifiedinChapterIIIandthebus

serviceenhancementsdescribedinChapterIV.Thefullsetofimprovementswillhelptoimprove

mobilityforalltravelersinthestationareasregardlessoftheirmodeoftravel.Improvementstothe

pedestrian,bicycleandtransitnetworksarenecessarytohelpdiverttripsawayfromSOVstoother

modes.Tosupportthismodechoiceshift,thissectionrecommendssomepoliciesthatshouldbe

encouragedin

the

vicinity,

including

Travel

Demand

Management

and

Intelligent

Transportation

Systems.

By2030,congestionintheRestonareawillbeasignificantproblem.Roadwayexpansionand

improvementprojectswillnotbeabletoprovidethecapacitytoaccommodateallofthevehicle

demandduringthepeakperiods.TravelDemandManagement(TDM)strategiesareprogramsand

Figure221:PotentialLocalConnectors


30/33

Final Report

50

policiesestablishedwiththegoalofreducingthenumberofvehicletripsmadeduringthepeakperiods.

TDMstrategieshavebeenimplementedsuccessfullyinareasthroughouttheWashingtonregion,

includingthenewlyrevitalizedurbanareaaroundSilverSpring,MD.SuccessfulTDMactionswill

encouragethetravelertotakeoneormoreofthefollowingactions:

Changetimeoftravel.

Change

path

of

travel,

such

that

trips

not

destined

to

the

area

find

other

routes

and

avoid

the

congestion.

Changemodeoftravel,sometravelerswillchoosetousetransit,sharearideorwalk/bike.

Notmakethetripatall.

TheincreasedcongestionexpectedintheRestonareaby2030willforcemanycommuterstocarefully

considertheirtransportationoptionstofindthebestsolutionforthem.Itisnecessarytoprovideawide

arrayoftransportationoptionssothateachindividualcanfindthesolutionthatworksbestforthem

whilesimultaneouslyreducingthelevelofcongestionexperiencedduringthepeakperiods.Transit,

bicyclingandwalkingmustbemadeviableoptionswhereverpossible,asdetailedinChapters3and4.

TDMpoliciesandprogramssupportedbyFairfaxCountyandlocalinterestsinRestonmayincludeanyof

thefollowing:

Transitfare

subsidies;

Parkingfeesatofficebuildings;

Preferentialparkingforcarpools;

Flexibleworkschedules;

Telecommutingopportunities;

Onsitesalesoftransitfaremedia;

GuaranteedRideHomeprograms;

Ridematchingprograms;

Transitinformationonsite;

OnsiteTDMcoordinator;

Carsharing;

VanpoolSupport;

and

Onsiteshowerfacilitiesforbicyclists.

Whenmarketedandadministeredappropriately,thecombinedeffectsofalloftheseprogramscanhave

asignificantimpactonthenumberofSOVtripsthataremadeduringapeakperiod.Forexample,in

studiesrecentlyconductedfortheTysonsCornerarea4,ithasbeenestimatedthatanaggressiveTDM

programwillbeimportantinachievinganonSOVmodeshareof20%inthearea.

IntelligentTransportationSystems(ITS)usetechnologytoimprovethetravelexperiencebyproviding

additionalinformation,

removing

delays

or

creating

amore

comfortable

environment

for

the

trip.

The

fullrangeofapplicationsofITSisstillbeingdevelopedandmaychangesignificantlyby2030.However,

someapplicationsthatwillbeusefulintheRestoncommunitymayincludethefollowing:

Realtimebuslocators;

Realtimebusarrivalinformationfortransitpassengers;

4Fairfax County Comprehensive Plan, 2007 Edition.


31/33

Final Report

51

Signalpriorityfortransitvehicles;and

Realtimetrafficinformation.

Anadditionalstudywouldbenecessarytodeterminethebestapplicationsandlocationsfortheseand

otherforthcomingtechnologies.

Thischapterhasdetailedmanyprojectsandpoliciesthatarerecommendedfortheareassurrounding

theWiehleAvenueandRestonParkwayMetrorailstations.Theseactionswillhelpeasetraffic

congestioninthearea,improvecirculationforallmodesoftravelandprovideeasieraccessandegress

tothestationsthemselves.Eachoftheseprojectsmustcompetewitheachotherandwiththeother

improvementsrecommendedinlaterchaptersofthisreportforscarceresources,includingtimeand

funding.Detailedengineeringanalysishasnotbeenperformedonanyoftherecommendedprojects,

howeverplanninglevelcostestimateshavebeendevelopedbasedonsimilarprojectsthathavebeen

completedinthearea.

Timingwillbeakeyissueinimplementationoftheserecommendedactions,asthereisalotofworkto

bedone

in

alimited

timeframe.

Based

on

the

phased

opening

of

the

two

stations

in

this

study,

some

of

theimprovementswillbenecessaryforaccesstotheWiehleAvenuestation(scheduledtoopenfirst)

andotherswillberequiredfortheopeningoftheRestonParkwaystation.Stillotherprojectswillbe

necessaryinthelongruntoeaseexpectedcongestioninthearea.Thesectionsbelowprovidecost

estimatesforeachoftheproposedactionsandalistofprioritiesfortheroadwayprojects.Integrated

prioritiesbetweenallofthedifferentmodescanbefoundinChapter5.

Fourteenroadwayimprovementprojectshavebeenidentifiedinthischapterthatwillimprove

accessibilityaroundtheproposedWiehleAvenueandRestonParkwayMetrorailstations.Costwillplay

animportantroleintheimplementationoftheseprojects,asfundingmustbeassuredbeforeany

designor

construction

can

begin.

Potential

funding

sources

for

projects

recommended

throughout

this

reportcanbefoundinChapter5.Roughcostestimateshavebeendevelopedforeachofthe

recommendedprojectsinthischapter.Theseestimatesarein2007dollarsandpricesareexpectedto

increaseannually.

Table29showstheestimatedcostforeachtypeofroadwayimprovement,thequantityofeach

recommendedinthestudyareaandthetotalestimatedconstructioncost.Thesecostsincludethe

constructioncostsforeachitemandasubstantialcontingencyforrightofwaycosts,engineeringwork

andotherpotentialexpenses,howeveractualcostsmaybemoreorlessdependingonthe

circumstancesencounteredateachlocation.Majorutilityrelocationisnotincluded,asinformationon

existingutilitiesisnotknown.Utilityrelocationcanbeexpensive.Annualcostsformaintenanceand

operationhavenotbeenincludedintheseestimates.

Ifalloftherecommendedprojectswereconstructedin2007,thetotalcostwouldbeapproximately$70

milliondollars.Almosthalfofthattotal(49%)isassociatedwiththevariouscontingenciesandrightof

waycoststhatcannotbeascertainedatthistime.Byfarthemostexpensiveitemintherecommended

roadwayprogramistheconstructionoftheSoapstoneConnectorovertheDIAAH,withatotal

estimatedcostof$32millionforthebridgeitselfandanadditional$10millionforotherroadway

construction,whichismorethanhalfofthetotalprogramcost.Theroadwaywideningassociatedwith


32/33

Final Report

52

theinternalstreetgridisestimatedtocostanadditional$11million,whilethebuslanesonSunsetHills

Rdareexpectedtocostapproximately$8.1million.

Table29:EstimatedRoadwayImprovementCosts

RoadActions Units Quantity UnitCostContingency

PerUnit TOTAL

NewSignal

Installation

EA.

4

$319,500

$431,300

$3,003,200

Installnew,orimproveexistingturnbay EA. 8 $213,000 $287,600 $4,004,800

NewtravellaneonRestonParkway mile 0.38 $1,863,800 $2,516,100 $1,659,100

Addinternalroadwaylinks mile 1.28 $3,727,500 $5,032,100 $11,212,300

Improve/Widenroadwayfrom2to4lanes mile 0.66 $8,413,500 $6,478,400 $9,871,500

NewbridgeoverDIAAH sqft 56,000 $320 $250 $31,920,000

BusLanesonSunsetHillsRd mile 1.86 $1,863,800 $2,516,100 $8,146,600

TOTAL $69,817,500

AppendixAincludesthetotalestimatedcostforeachofthefourteenimprovements(AN)

recommendedinthischapter.

Eachoftheroadwayprojectsthatarerecommendedinthischapterisimportantinordertoprovidethe

bestpossibleaccesstotheWiehleAvenueandRestonParkwayMetrorailstations.Someimprovements

provideagreaterincreaseinaccessibilitythanothers,andarethereforeprioritizedmoreheavily.

Additionally,astheraillineisscheduledtobeopenedinRestonintwophases,thefirstprioritymustbe

placedonprovidingaccesstotheWiehleAvenuestation,whichwillbeopeninginthefirstphase.Table

210belowshowsthefourteenrecommendedroadwayprojectsaccordingtothepriorityforproviding

improvedaccessibilityintheimmediatestationvicinities.Thisprioritizationtablerecognizesthat

importancedoesnotalwaysmatchwitheaseofimplementationandthatsomeoftheveryimportant,

highpriorityprojects(suchastheSoapstoneConnector)arelargescaleprojectsthatwilltake

significantlylonger

than

smaller

projects

to

plan,

engineer

and

construct.

Still

others

may

be

lower

prioritysmallprojects,orprojectsthatcanbecompletedinassociationwithredevelopmentprojectsin

thearea.Whenopportunitiesarisetoimplementtheseactionstheyshouldnotbepassedbysimply

becausetheyarelowerontheprioritylisting.

Table210:RoadwayImprovementPriorities

Project Priority

Includedin

RecordOf

Decision Comments

B

Newleftturnlaneforwestboundleftturningmovementat

SunsetHillsRd&IsaacNewtonSq.Thiswouldreplacethe

sharedleftthroughlanebyprovidingadedicatedturnlane.

1st

Priority Yes

C

Addasecond

left

turn

lane

for

northbound

traffic

at

Wiehle

Ave&MetroAccess(betweenSunsetHillsRd&DIAAH)and

provideasecondinboundlane.

1st

Priority Yes

DAddanadditionalleftturnlaneontheeastboundDIAAH

rampatWiehleAve

1st

Priority Yes

EImprovetheexistingrightturnlaneoneastboundSunset

HillsRdatWiehleAve

1st

Priority Yes


33/33

Final Report

Project Priority

Includedin

RecordOf

Decision Comments

FImprovetheexistingrightturnlaneforwestboundSunrise

ValleyDratWiehleAve

1st

Priority Yes

I

Provideanew

connection

over

the

DIAAH

between

SoapstoneRdandIsaacNewtonSqW,toconnectthe

majoreastwestroadways:SunsetHillsRd&SunriseValley

Dr.

1st

Priority No Longtermimprovement

K

IsaacNewtonSquareWestfromIsaacNewtonSquare

Southtothestationasanextensionoftheproposed

SoapstoneConnector.

1st

Priority No

ANewsignalandturnlanesonSunsetHillsRdforaccessinto

theproposedRestonParkwayMetrorailstation

2nd

Priority Yes

G

AddnorthboundthoughlaneonRestonParkwayatSunrise

ValleyDr,continuingthelanetotherampforeastbound

DIAAH

2nd

Priority Yes

HImprove

the

right

turn

lane

for

southbound

Reston

Parkway

atSunriseValleyDr2

nd

Priority Yes

JProvidebuslanesonSunsetHillsRdfromWiehleAvetoOld

RestonAve

3rd

Priority No Longtermimprovement

L

TheStationEntrance(alreadyplannedforimprovementsas

partofstationconstruction)shouldbeextendedacross

WiehleAvenuetothePrivateDrivewayasfareastas

SamuelMorseDr.

3rd

Priority No

Tobeconstructed(if

possible)inassociation

withredevelopment

M

MichaelFaradayCourtextensionfromthenewroadway

describedin(L)northtotheextendedRogerBaconDr

describedin(N)

3rd

Priority No

Tobeconstructed(if

possible)inassociation

withredevelopment

NExtension/improvements

to

Isaac

Newton

Square

South

fromIsaacNewtonSquareWesttoWildlifeCenterDrive.

3rd

Priority No

Tobeconstructed(if

possible)in

association

withredevelopment

AlloftherecommendedprojectsthatwereincludedintheRecordofDecision(ROD)aremitigation

effortsrequiredaspartoftheconstructionoftherailproject.Theseprojectswillnotbepaidforby

FairfaxCountyandshouldallbeconstructedinconjunctionwithPhaseIoftherailproject.Basedon

thisstudy,thoseRODprojectsthataredirectlyadjacenttotheWiehleAvenuestationaredesignatedas

firstprioritybecausethisstationwillopenfirst.Inaddition,theSoapstoneConnectoranditsextension

acrossSunsetHillsRdtoIsaacNewtonSquarearealsorankedas1stpriorityprojectforthesame

reasons.SecondpriorityprojectsarethosewhichimproveaccessprimarilytotheRestonParkway

station.Thethirdprioritygroupingisreservedforprojectsthatwillhelprelievesomeofthecongestion

thatis

expected

on

along

term

basis

in

the

station

areas.

Amultimodalprioritylistingthatincorporatestheaboveprioritiesandalsoincludesallofthemodes

studiedinthisplanisthemainsubjectofChapter5.

Documents

RMAG Consultant Traffic Analysis (Ch.2)