Exhibit 9-1 · Exhibit 9-1.1 The liquefiable soils behind the seawall and under the relieving platform would be improved by strengthening them with cement grout. Similarly, a small

118 Surface Alternative

Exhibit 9-1

1 What is the Surface Alternative?

How would it replace SR 99 and the viaduct?

The Surface Alternative includes replacing SR 99with the following elements as shown in Exhibit 9-1:

� South - Replace the existing viaduct with an at-grade roadway. Replace ramps at First Avenue S.with an elevated interchange connecting SR 99 toSR 519 at S. Atlantic Street and S. RoyalBrougham Way.

� Central - Replace the viaduct with a six-lane, at-grade roadway north of Yesler Way. The roadwaywould have three lanes in each direction withturn pockets. Two new overpasses would be builtin the central section. One would be for ferrytraffic only. It would be located along ColumbiaStreet, connecting the Colman Dock FerryTerminal to First Avenue. A second overpasswould be aligned along Seneca Street connectingFirst Avenue to Alaskan Way. Build a new aerialconnection between Pike Street and the BatteryStreet Tunnel. The new connection would havetwo lanes in each direction and it would be widerthan the existing facility. New ramps would bebuilt at Western and Elliott Avenues. Ramps atBattery Street would remain open for only emer-gency vehicle use. Also, in the Pioneer Squarearea, the number of lanes of traffic on FirstAvenue would be increased from one lane ineach direction to two lanes in each direction.

� North Waterfront - Reconstruct the Alaskan Waysurface street with four lanes.

� North - Improve the Battery Street Tunnel forfire and life safety by adding emergency exits,upgrading electrical systems, adding ventilation,and upgrading the fire suppression system.Widen the Mercer Underpass by expandingMercer Street from four eastbound lanes to aseven-lane, two-way roadway with three lanes in

each direction and a center turn lane. Build anew two-lane bridge over Aurora/SR 99 atThomas Street, and close Broad Street from FifthAvenue to Ninth Avenue.

The Surface Alternative includes two possible options:

� South - Replace the existing viaduct (SR 99) withan at-grade roadway and no elevated interchangeat SR 519. Instead, access to SR 519 would beprovided by signalized at-grade intersections.

� North - Add signals on Aurora Avenue atHarrison, Republican, and Roy Streets.

How would it replace the seawall?

The seawall replacement design is the same for theSurface Alternative as what was described for theRebuild Alternative. The seawall would be replacedwith drilled shafts and improved soils from S. Wash-ington Street up to Bay Street as shown in Exhibit 9-1.1 The liquefiable soils behind the seawalland under the relieving platform would be improvedby strengthening them with cement grout. Similarly,a small section of existing sheet pile wall from near

S. King Street to S. Washington Street would be re-moved and replaced with improved soils and drilledshafts. In some areas along the seawall, drilled shafts may not be needed and the soils would only be improved.

2 How would the Surface Alternative be built?

The construction steps described below are prelimi-nary and they may change based on additional projectdesign.

Construction of this alternative would begin by relo-cating utilities. Next, the seawall would be replaced

and construction of the west half of the SR 519 over-pass would begin. Improvements associated with theWidened Mercer Underpass would be built, anddetours on Broad Street would be established.

Next, the southbound section of the viaduct connect-ing Pike Street to the Battery Street Tunnel would betorn down and a new aerial structure would be built.Improvements to the southbound half of the BatteryStreet Tunnel would be completed, and the west halfof the SR 519 connection would be completed.

The northbound section of the viaduct connectingPike Street to the Battery Street Tunnel would betorn down and a new aerial structure would be built.Improvements to the northbound half of the BatteryStreet Tunnel would be completed. In addition, theviaduct would be torn down, and the at-grade SR 99roadway would be built from S. Holgate Street toPike Street. The east half of the SR 519 connectionwould be built.

Finally, utilities would be placed in their final loca-tions, the Alaskan Way surface street would berebuilt, and traffic would be routed to its permanentlocations. During construction, at least two lanes ofSR 99 traffic would be maintained in each direction,and one lane of traffic in each direction would bemaintained on the Alaskan Way surface street.Additional information about construction is provid-ed in Chapter 10.

3 How would the Surface Alternative change access?

How would it change vehicle access in the south?

Currently in the south end, SR 99 has a southboundoff-ramp and a northbound on-ramp connecting at

CHAPTER 9 - SURFACE ALTERNATIVE

Alaskan Way Viaduct & Seawall Replacement Project Draft Environmental Impact Statement 119

Appendix B contains additional information describing theSurface Alternative.

How can soils be improved or strengthened?

Soil can be strengthened by mixing it with cement grout.Construction methods that may be used to strengthen soilfor this project are described in more detail in Chapter 10.

Appendix W contains preliminary engineering drawings ofthis alternative.

Appendix C contains additional details about transportation.

1No seawall work is required for any of thealternatives between Blanchard andBattery Streets adjacent to the Bell HarborInternational Conference Center.

First Avenue S. near Railroad Way S. The SurfaceAlternative would replace the First Avenue S. rampswith an elevated interchange over SR 99. The inter-change would connect SR 99 to SR 519 at S. AtlanticStreet and S. Royal Brougham Way. It would improveaccess in the south end by adding ramps that wouldprovide connections to the stadiums and SR 519,which connects to I-90. The SR 519 interchangewould also separate vehicles and rail operations.Currently these operations are not separated, andthere are times when trains block roadway connec-tions at S. Atlantic Street. Traffic movements provid-ed by the new ramps would include:

� Northbound off from SR 99 near S. HolgateStreet to S. Atlantic Street and S. RoyalBrougham Way.

� Northbound on from S. Royal Brougham Way toSR 99.

� Southbound on from E. Marginal Way near S.Holgate Street to SR 99.

� Southbound off from SR 99 to S. Atlantic Streetand S. Royal Brougham Way.

If the option were selected, the existing viaductwould be replaced with an at-grade roadway withoutan elevated interchange connecting SR 99 to SR 519Instead, access to SR 519 would be provided by sig-nalized at-grade intersections at S. Atlantic Street andS. Royal Brougham Way.

How would it change railroad access?

The Surface Alternative would change railroad accessin the south end by shifting existing rail yards and bymoving the tail track. The new at-grade SR 99 wouldbe built west of the existing viaduct where theWhatcom Rail Yard is currently located. As a result,the Whatcom Rail Yard would be removed and theBurlington Northern Santa Fe (BNSF) SeattleInternational Gateway (SIG) Rail Yard would beexpanded and reconfigured to include the relocatedWhatcom Rail Yard tracks. The Whatcom Rail Yardis currently located on the west side of SR 99, and theBNSF SIG Rail Yard is east of SR 99.

In addition, the tail track would need to be movedfrom the west side of SR 99 to the east side of SR 99.

It would also need to be shifted south from the S.King Street area to S. Royal Brougham Way. Thecombination of shifting the tail track south and incor-porating the Whatcom Rail Yard into the BNSF SIGRail Yard would result in the need to shift the entireBNSF SIG Rail Yard south from S. Hanford Street toS. Spokane Street. In addition, some minor track con-struction would be required south of S. SpokaneStreet near S. Dakota Street.

The Surface Alternatives does not require the tailtrack to be located at S. Royal Brougham Way. It ispossible that the tail track could terminate nearRailroad Way S., which would eliminate the need toshift portions of the BNSF SIG Rail Yard south to S.Spokane Street.

How would it change vehicle access for ferries?

People driving to the ferry get there via the AlaskanWay surface street, often by taking a left at YeslerWay. When Colman Dock is full, drivers wait for theferry under the viaduct south of Railroad Way S.Drivers leaving Colman Dock use Marion Street orAlaskan Way.

The Surface Alternative would change where driverswould wait for the ferry when Colman Dock is full. Itwould also change the way drivers get to ColmanDock, and it would add a new way for drivers to exitColman Dock.

With this alternative, the viaduct would be removedand replaced with an at-grade roadway south of YeslerWay. Therefore, the existing ferry holding area underthe viaduct would need to be relocated west of SR 99on part of Terminal 46, just south of S. King Street.With this ferry holding location, traffic flow would beimproved for both Alaskan Way surface street trafficand ferry traffic by building a separate roadway con-necting the holding area to Colman Dock. Improvedtraffic flow at Colman Dock could also make ferryloading and unloading operations more efficient.

The separate ferry access roadway would be built on anew over-water pier between S. Washington Streetand Yesler Way. Drivers would get to Colman Dock

using S. King Street and the new ferry access roadway.Drivers leaving Colman Dock would be able to exitwhere they do now at Marion Street or Alaskan Way,or they could exit using the roadway to S. King Street.

The new ferry access roadway and over-water pier isneeded for some additional reasons. The new pierwould provide space to relocate the historic Washing-ton Street Boat Landing, and it could provide newshoreline access to pedestrians and bicyclists. Duringconstruction, the roadway and pier are needed tomaintain ferry access and egress. They could alsoaccommodate construction staging activities.

How would it change vehicle access into or out ofdowntown?

For this alternative, an expanded Alaskan Way sur-face street would replace the viaduct. From Yesler

Surface Alternative

Typical Building-Setback varies

Promenade

Parking

Waterfront Streetcar

Bikeway

Alaskan Way Alaskan Way

Existing Viaduct

25’ 8’ 13’ 12’ 10’ 6’14’ 6’ 33’ 33’ 14’

Existing Seawallto be Removed

Existing Seawall

Soft and Liquifiable Soil

Top of Competent Soils

Soil Improvements

Soft and Liquifiable Soil

Top of Competent Soils

ServiceLane

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Existing Pier Buildings

Existing

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Exhibit 9-2

What is the tail track?

The tail track is a single railroad track that connects theBurlington Northern Santa Fe (BNSF) Seattle InternationalGateway (SIG) Rail Yard on the east side of SR 99 to theWhatcom Rail Yard located west of SR 99..

The tail track is used to assemble and sort railcars for boththe Whatcom and BNSF SIG Rail Yards.

Bikeway

Way up to Pike Street, a signalized roadway withthree lanes in each direction would be constructed.Turn pockets would be provided in various locations.A one-lane southbound service roadway with parkingwould be provided adjacent to the waterfront piersand businesses.

Drivers would access downtown directly from theAlaskan Way surface street at several signalized crossstreets. New ramps would be built at S. King Streetproviding access to downtown. Drivers could alsoreach downtown by using the new SR 519 interchangeat S. Atlantic Street and S. Royal Brougham Way.

An additional route out of downtown would be provided by a westbound extension of Seneca Streetconnecting First Avenue and Western Avenue toAlaskan Way.

From Pike Street, the at-grade roadway would transi-tion to side-by-side aerial structures connecting to theBattery Street Tunnel. Ramps at Elliott and WesternAvenues would be provided for traffic to and fromthe Ballard/Interbay and Belltown areas. Anotherpossibility is that the northbound and southboundramps would both end at Elliott Avenue, with a sur-face street connection for northbound traffic toreach Western Avenue. The existing ramps at BatteryStreet would be closed to general traffic and wouldremain open only for emergency vehicles.

How would it change the Alaskan Way surfacestreet for vehicles?

With the Surface Alternative, the Alaskan Way sur-face street would be expanded to six lanes throughdowntown and it would become the SR 99 mainlinethrough downtown. As a result, the number of vehicles traveling on Alaskan Way would increase substantially.

Since the viaduct would be removed, there are severalpossible ways the surface street could be configured.One possible surface street design for the SurfaceAlternative is shown in Exhibit 9-2. The surface streetwould have expanded pedestrian promenades, newbicycle lanes, one or two trolley tracks, on-street

parking, and service roadways for piers and adjacentbuildings.

How would the Battery Street Tunnel change?

Fire and life safety conditions in the Battery StreetTunnel would be improved by adding emergencyexits, upgrading electrical systems, adding ventila-tion, and upgrading the fire suppression system.

How would it change vehicle access north of theBattery Street Tunnel?

Connections north of the Battery Street Tunnel areimportant for traffic detours during construction. For the Surface Alternative, the Battery Street Tunnelwould be upgraded and a new aerial connection be-tween Pike Street and the Battery Street Tunnelwould be built. During construction of these improve-ments, traffic along this section of SR 99 would needto be detoured. Improvements to Mercer Street andother streets north of the Battery Street Tunnel wouldallow these streets to handle the additional traffic.After construction, these north end improvementswould provide long-term benefits that are describedbelow.

In the north end, Mercer Street would be widenedfrom four eastbound lanes to a two-way, seven-lanestreet. Mercer would have three lanes in each direc-tion and a center turn lane between Fifth and DexterAvenues. In addition, a two-lane bridge would bebuilt over Aurora/SR 99 at Thomas Street. Duringconstruction, the Mercer Street and Thomas Streetim-provements would change traffic flow in the northend to allow southbound SR 99 traffic to be detouredonto Broad Street. Once construction was completed,existing ramps to Mercer and Broad Streets would beremoved. After construction, the Mercer and ThomasStreet upgrades would improve east-west circulationin the South Lake Union and Uptown neighbor-hoods. East-west connections for vehicles, bicyclists,and pedestrians are constrained by Aurora/SR 99because it cuts off the street grid. Once constructionwas completed, Broad Street could be closed betweenFifth and Ninth Avenues, allowing for more streets tobe reconnected.

The other option is to leave the north end of the proj-ect area similar to its current condition; signals wouldbe added to Aurora/SR 99 at Harrison, Republican,and Roy Streets. The signals would improve east-westtraffic flow across Aurora/SR 99 by reconnectingpart of the street grid. However, this option wouldimpede traffic flow on Aurora Avenue.

How would it change bicycle access?

The Surface Alternative would change bicycle accessby modifying the location of the Waterfront Trail.The existing Waterfront Trail begins at S. RoyalBrougham Way and runs along the east of side of E.Marginal Way/Alaskan Way to Bell Street. It is sepa-rated from the Alaskan Way surface street and isshared by bicyclists and pedestrians. The separated,shared path would be extended south from S. RoyalBrougham Way to just south of S. Atlantic Street.From S. Atlantic Street to Yesler Way, the WaterfrontTrail would be moved from the east side of E.Marginal Way/Alaskan Way to the west side.Additionally, it may be possible to develop a spurshared use trail that would lead diagonally from thenorth side of Seahawks Stadium (midway between S.Atlantic Street and S. Royal Brougham Way) to thesouthwest corner of the intersection of Alaskan Wayand S. King Street. Between Yesler Way and PineStreet, the Waterfront Trail would be replaced withstriped bicycle lanes along each side of the AlaskanWay surface street. North of Pine Street, cyclistswould be routed back to the Waterfront Trail, whichwould be located in its present location on the eastside of Alaskan Way. Additionally, striped bike laneswould be located on each side of the SR 99 roadwayas it ascends to the Battery Street Tunnel. Theselanes would connect to a single bike lane on the westside of Elliott Avenue that would run between Lenoraand Bell Streets.

How would it change pedestrian access?

As with bicycle access, the Surface Alternative wouldchange pedestrian access by modifying the locationof the Waterfront Trail. Additionally, sidewalkswould be added in parts of the project corridor. TheWaterfront Trail would begin south of S. Atlantic


Other possible surface street design variations are shownin Appendix X, Design Variations for Surface StreetImprovements.


Street on the west side of the project corridor, andsidewalks would be located on the east side of E.Marginal Way/ Alaskan Way.

Between S. King Street and Yesler Way, theWaterfront Trail would be replaced with a sidewalkalong each side of the Alaskan Way surface street.The separated, shared path would be extended southfrom S. Royal Brougham Way to just south of S.Atlantic Street. From S. Atlantic Street to Yesler Way,the Waterfront Trail would be moved from the eastside of E. Marginal Way/Alaskan Way to the westside. Additionally, it may be possible to develop ashared use trail that would lead diagonally from thenorth side of Seahawks Stadium (midway between S.Atlantic Street and S. Royal Brougham Way) to thesouthwest corner of the intersection of Alaskan Wayand S. King Street. North of Yesler Way pedestrianscould walk on sidewalks on the east side of AlaskanWay or the waterfront promenade located on thewest side of Alaskan Way. North of Pine Street,pedestrians could walk on either the waterfrontpromenade on the west side of Alaskan Way or theWaterfront Trail on the east side of Alaskan Way.

In the SR 519 area, pedestrian access would be main-tained by continuing the sidewalks on Alaskan Wayand associated local streets on the SR 519 inter-change. Connections across SR 99 would be providedby sidewalks on S. Royal Brougham Way and S.Atlantic Street, which would cross over the SR 99mainline.

All of the alternatives would add a new over-waterpier connecting Pier 48 near the end of S.Washington Street with the Colman Dock FerryTerminal. The pier would accommodate pedestrianson its waterside edge. In addition, for all alternatives,a pedestrian bridge may be added over the AlaskanWay surface street connecting the Colman DockFerry Terminal near Madison Street. The existingpedestrian bridge for people traveling to and fromthe Ferry Terminal at Marion Street would be rebuiltnear its existing location.

North of the Battery Street Tunnel, a bridge wouldbe added at Thomas Street across SR 99. This bridge

would have sidewalks on both sides, which would adda new east-west route for pedestrians in the SouthLake Union area. In addition, the existing sidewalkson both sides of Mercer Street would be widened insome areas, which would improve conditions forpedestrians.

4 How would the Surface Alternative affect traveltimes and traffic flow?

How would daily traffic patterns and volumes onSR 99 change with the Surface Alternative?

Mainline SR 99 traffic volumes are anticipated to besubstantially lower in both directions in downtownSeattle than those forecasted for the existing facilityin 2030. This is a result of a general decrease incapacity on SR 99 through the central section of thecorridor. SR 99 and Alaskan Way surface street traf-fic would both be accommodated on the Alaskan Waysurface street. In the central section of SR 99 whereexisting traffic volumes are the highest, daily traffic isexpected to peak at 74,000 vehicles per day comparedwith 126,000 vehicles per day for year 2030 existingconditions.

With the Surface Alternative, the number of hoursthat the SR 99 mainline would be congested is higherthan the year 2030 existing facility as shown in Exhibit 9-3.

In the south end of the project area, mainline SR 99traffic volumes and ramp volumes are expected toincrease slightly due to improved access between SR99 and SR 519. North of S. King Street, traffic vol-umes on the SR 99 mainline are reduced comparedto the existing facility in 2030 due to reduced road-way capacity. Traffic volumes north of the BatteryStreet Tunnel are expected to increase comparedwith 2030 existing conditions

How would travel times and travel speeds changeon SR 99 with the Surface Alternative

The Surface Alternative is expected to result in longertravel times and lower speeds than the existing facilityin 2030 for most trips. Travel times would increasefor all of the trips considered, as shown below inExhibit 9-4. Travel times for drivers traveling throughdowntown would increase more than trips destinedfor downtown. For example, northbound travel timesduring the PM Peak from S. Spokane Street to theAurora Bridge would increase from 12 minutes forthe 2030 existing facility to 33 minutes with theSurface Alternative. In the southbound direction, thissame trip is expected to increase from 9 minutes to 16

What is the �year 2030 existing facility� and why is

it evaluated?

The year 2030 existing facility shows how much traffic isprojected to use the existing SR 99 facility in the year2030. It takes into account future population growth andother funded transportation projects such as Monorailand Link light rail. It assumes that the viaduct wouldremain in the year 2030 in its existing condition. We knowit is unlikely that the viaduct will last until 2030. However,the information provides a baseline that can be comparedwith traffic conditions for the proposed alternatives.

Surface Alternative Travel TimesDuring the PM Peak

Exhibit 9-4

minutes. Conversely, trips with downtown destina-tions, such as trips between downtown and theAurora Bridge, would increase only slightly com-pared with the 2030 existing facility.

Average travel speeds would be reduced in most sec-tions of the corridor with the Surface Alternative, asshown in Exhibit 9-5. Speeds would be reduced forthree reasons:

1 Posted speeds would be reduced to 30 miles perhour for this alternative, which is lower thanexisting posted speeds for SR 99.

2 SR 99 traffic would be stopped periodically bytraffic signals. Currently through downtown, SR99 is a free-flowing limited access facility withouttraffic signals.

3 The corridor would be more congested than it iscurrently, which would also decrease travelspeeds.

For the Surface Alternative, average traffic speedsthrough downtown would be reduced to range from8 to 15 miles per hour during the PM Peak hour.This is lower than expected speeds, ranging from 27to 40 miles per hour, for the existing facility in 2030.Speeds in most sections of the corridor would bereduced, with the exception of speeds in the BatteryStreet Tunnel, which are expected to slightly increasecompared with the 2030 existing facility.

How would local streets and intersections operate?

Traffic on local streets and delay at intersectionswould not substantially change in the south andnorth waterfront areas as shown in Exhibit 9-6.Intersection delay would increase in downtown andthe area north of the Battery Street Tunnel.

In the south, intersections at First Avenue S. and S.Royal Brougham Way and First Avenue S. and S.Atlantic Street would slightly improve from highlycongested conditions to congested conditions.Conditions at these intersections would improvebecause fewer drivers would need to turn to connectwith SR 519. Also, the new interchange would distrib-ute traffic between two streets, compared with the


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Exhibit 9-5

How are congested operations on SR 99 defined?

The number of hours SR 99 would be congested was esti-mated by determining how long the busiest sections of SR99 would be expected to have regular traffic slow downsor stop and go traffic.

What is the PM Peak Hour and why is traffic data ana-

lyzed for the PM Peak?

The PM Peak Hour is the time period when traffic is heavi-est during the late afternoon commute. For SR 99, the PMPeak Hour occurs from 4:00 to 5:00 p.m. For this project,PM Peak data was evaluated because overall traffic condi-tions in and around the project area are the most con-gested during that time of day.

existing facility that distributes traffic at only onestreet (First Avenue S).

In the downtown area, the number of congestedintersections would increase from eight intersectionsto fourteen. The number of congested intersectionswould be increased because some drivers that cur-rently use SR 99 would use surface streets instead.With the Surface Alternative, traffic on other citystreets through downtown is expected to increase by16 percent. Also, intersection delay at Alaskan Wayand Yesler Way would be slightly reduced from 124seconds for the year 2030 existing facility to 99 sec-onds with the Surface Alternative. Delay at YeslerWay would be reduced because ferry access toColman Dock would be moved from Yesler Way to S.King Street. The tradeoff is that an intersectionwould be added at Alaskan Way and S. King Street.This intersection would have about 158 seconds ofdelay during the PM Peak.

In the north end, the Surface Alternative would havemore congested intersections than the 2030 existingfacility. The Surface Alternative proposes to widenMercer Street and convert it to a two-way streetbetween Fifth Avenue and Dexter Avenue. At theintersections of Mercer Street/Fifth Avenue andMercer Street/Dexter Avenue, Mercer would transi-tion back to a one-way street. Congestion is expectedto increase near the areas where Mercer would con-vert from a two-way street to a one-way street (seeExhibit 9-6). Congestion projected in this area couldget better if improvements beyond the limits of thisproject were made. The City of Seattle is currentlystudying several alternatives to improve the roadwaynetwork in the South Lake Union area as a separateproject. Improvements to the roadway network in theSouth Lake Union area are not necessary for northend improvements proposed as part of the AlaskanWay Viaduct and Seawall Replacement Project.

At first glance, it may seem that the Mercer improve-ments would provide little benefit to the area sincecongestion would increase at a few north end intersec-tions. However, what is not captured by the intersec-tion analysis is the fact that the north end improve-

ments would increase east-west mobility across SR 99,which is currently constrained. Also, the north endimprovements could help reduce congestion duringconstruction.

How would traffic volumes change on the AlaskanWay surface street?

Traffic volumes on the Alaskan Way surface streetwould increase substantially to 74,000 trips per day,compared with 11,000 trips per day estimated for the2030 existing facility. Traffic volumes on AlaskanWay would increase because SR 99 and Alaskan Waysurface street traffic would both be accommodatedon Alaskan Way. Alaskan Way would be widened tohelp accommodate the additional trips. However,intersection delay would increase at several locations,travel times for several trips would increase, and trav-el speeds in most areas would be reduced. With theSurface Alternative, Alaskan Way could be congestedfor up to 9 hours a day.

Would traffic volumes on other parallel city streets change?

In the south end, the volume of traffic using parallelsurface streets would decrease slightly due toimproved ramp connections near the stadiums and SR 519.

In the central section of the project area, daily trafficvolumes on parallel city streets would increase by 16percent (approximately 13,000 vehicles a day). Thevolume of traffic on city streets is expected to increasebecause some drivers that currently use SR 99 woulduse downtown city streets instead. Because traffic vol-umes would increase on downtown streets, in-tersec-tion delay would also increase as previously described.

In the north end of the project area, the number ofdrivers using city streets would also increase. Thisshift would be partially due to improved city streetconnections at Thomas and Mercer Streets and alsodue to an increased number of drivers exiting SR 99in this area to avoid the congested central waterfront.


5

99

5

99

Exhibit 9-6

2030 Existing Facility Surface

Bypass Tunnel Alternative Congested IntersectionsDuring the PM Peak

Would the Surface Alternative affect traffic vol-umes on I-5?

Due to increased travel times, congestion, andreduced speeds, many drivers would choose to avoidusing SR 99, particularly for trips through downtown.As a result, daily traffic volumes through downtownon the already congested I-5 facility would increase byabout 6 percent (or 22,000 trips a day) in 2030 if theSurface Alternative is built.

How would the options affect traffic conditions ifthey were built instead of the alternative?

The Surface Alternative includes options in the southand north sections. These could become part of thepreferred alternative in the Final EIS. In brief, here'show they would affect traffic:

� In the south end - If the connections to SR 519are made at-grade with signalized intersections atS. Atlantic Street and S. Royal Brougham Way,traffic delay would increase over what is expectedfor the Surface Alternative.

� In the north end - Traffic flow on SR 99 in thenorth end would likely be degraded comparedwith existing conditions if signals were placedalong Aurora/SR 99. Congested conditionswould be expected at these intersections, andoverall speed through this area would likely bedecreased. The tradeoff is that east-west mobilitywould be improved by adding connections acrossAurora/SR 99 at Thomas, Harrison, andRepublican Streets.

5 How would the Surface Alternative change condi-tions for freight and transit?

How would the Surface Alternative change condi-tions for freight?

The Surface Alternative is expected to result inlonger travel times and lower speeds than the existingfacility in 2030 for most trips, which would affectfreight. For the most part, conditions for freightwould be degraded compared with conditions for the2030 existing facility.

Travel times for several common freight tripsthrough downtown would increase with the Surface

Alternative. For example, northbound travel timesduring the PM Peak from the Ballard Bridge to theSR 519 ramps would increase from 19 minutes for the2030 existing facility to 27 minutes with the SurfaceAlternative. In the southbound direction, this sametrip would increase from 13 minutes to 22 minutes.

The Surface Alternative would reduce travel speedsin several locations. In the stadium area, average trav-el speeds during the PM Peak hour would range from10 to 36 miles per hour for the Surface Alternative,compared with 44 to 46 miles per hour for the 2030existing facility.

Even though travel times and travel speeds would bedegraded, there are elements of the project thatwould benefit freight. Freight connections would beimproved compared with the existing facility becausea new interchange would be built at S. Atlantic Streetand S. Royal Brougham Way. This interchange wouldimprove freight connections between the Duwamishindustrial area, Harbor Island, SR 519, and I-90.

How would the Surface Alternative change transit conditions?

Travel times for transit would change with theSurface Alternative. However, transit does not use SR99 as a through route, so travel times would be lessaffected for buses than for freight and other vehiclesusing SR 99 as a through route.

Bus routes that currently reach downtown fromColumbia and Seneca Streets would be changed sincethe Columbia and Seneca ramps would be replaced.Buses could reach downtown using several possibleaccess points; however, transit would most likely useramps to S. King Street or the SR 519 ramps. Ineither case, travel times to the downtown area wouldincrease. This increase would be due in part to thechange in route because buses could access the entireFourth Avenue corridor, thereby expanding servicesto growing employment centers in the InternationalDistrict and Pioneer Square area. The other reason isthat congestion is expected to increase in the corri-dor. The effects of congestion on transit travel timescould be reduced through implementation of transit

priority measures. The City of Seattle's policy is togive transit priority in the downtown area, and meas-ures to maintain transit speed and reliability wouldlikely be implemented if downtown streets becamemore congested. Please note, if buses were routed tothe SR 519 ramps, transit would be subject to trafficcongestion in the stadium area during events unlessalternate routes were developed.

The degree to which travel times would increasewould depend on the bus route and the time of thetrip. For example, during the PM Peak, travel timesfor buses headed southbound from between down-town and S. Spokane Street would likely be similar tothose for the 2030 existing facility. However, busesheaded northbound would likely experience longertravel times, since this trip would increase from 10minutes to 20 minutes.

On the north end, buses would continue to accessdowntown from the Denny Way ramps. Travel timesfor buses using the Denny Way ramps would alsoincrease slightly with the 2030 existing facility. Forexample, northbound trips leaving from downtownwould increase from 12 minutes for the 2030 existingfacility to 14 minutes for the Surface Alternative.

The lead agencies are committed to improving othertransportation options in the corridor as part of thisproject, particularly as part of construction. AFlexible Transportation Package has been developedthat includes several different programs and tools torespond to varying needs in the corridor. Most of thetools are designed to decrease reliance on single-occupancy vehicles and increase other modes oftransportation during construction of the project,though some investments would provide long-termbenefits. The range of programs that could be imple-mented to provide long-term benefits once the proj-ect is completed include implementing parkingstrategies to decrease long-term parking in the areaand installing traffic management and transit prioritysystems. A more defined Flexible TransportationPackage will be presented in the Final EIS as part ofthe preferred alternative.

What are congested and highly congested intersections?

Congested intersections are intersections that cause driv-ers considerable delay. A driver might wait between oneand two minutes to get through a traffic signal at a con-gested intersection. At a highly congested intersection, adriver might wait two minutes or more to get through thetraffic signal.

Chapter 10 and Appendix B contain additional detailsabout tools proposed for the Flexible TransportationPackage.


6 How would the Surface Alternative improve road-way safety?

The Surface Alternative would replace the deteriorat-ing structure with a new roadway, reducing seismicrisks. However, putting SR 99 traffic on the surfaceand through intersections would increase the acci-dent rate for both vehicles and pedestrians alongmuch of the corridor.

In the south end, the viaduct would be removed andreplaced with a new at-grade roadway from S.Holgate Street up to near S. King Street. The rampsat First Avenue S. would be removed and replacedwith improved ramps with wider shoulders in the S.Atlantic Street and S. Royal Brougham Way area. Ifthe south end option were constructed with theSurface Alternative, ramps to S. Atlantic Street and S.Royal Brougham Way would not be provided;instead, these connections would remain at-grade andwould be controlled by traffic signals. The optionwould introduce cross-street access on SR 99, whichwould increase the likelihood of intersection and con-gestion-related accidents.

With the Surface Alternative, the character of SR 99along the waterfront changes from a limited accesshighway to a large arterial with signalized intersec-tions. From about S. King Street north to BroadStreet, traffic on the Alaskan Way surface streetwould increase substantially, particularly up to PikeStreet. This additional traffic would increase the over-all number of vehicle and pedestrian accidents andthe potential for injuries.

North of Pike Street, SR 99 would transition to an aer-ial structure that would connect to the Battery StreetTunnel. Ramps to Elliott and Western Avenues wouldbe provided and would be improved over existingconditions. In addition, there is the option of connect-ing both ramps to Elliott Avenue, which would not beexpected to compromise traffic safety. The BatteryStreet ramps would remain open to only emergencyvehicles, which would improve roadway safety.

In the south section, if the option with signals at S.Atlantic Street and S. Royal Brougham Way were con-

structed, the number of injury accident rates wouldbe expected to increase. North of the Battery StreetTunnel, the Widened Mercer Underpass and newThomas Street bridge would provide new pathwaysfor pedestrians to safely cross this section of SR 99. Ifthe option were constructed, signals would be addedwhere SR 99 intersects with Thomas, Harrison, andRoy Streets. These signals would add cross-street traf-fic, which can increase the likelihood of intersectionand congestion-related injury accidents for vehiclesand pedestrians. Also, if northbound traffic backs upinto the Battery Street Tunnel, more accidents wouldbe expected. Emergency access to accidents would bemore difficult in the tunnel than at other locations.

7 How would the Surface Alternative affect parking?

There are 2,038 parking spaces located in the projectarea. As shown in Exhibit 9-7, a total of about 720parking spaces would be removed with the SurfaceAlternative between the south end and the northwaterfront area. An additional 40 spaces would beremoved in the north end due to the improvementsassociated with the Widened Mercer Underpass.

The majority of parking spaces that would beremoved are free, long-term spaces located in thesouth section of the project area. Approximatelyseven short-term spaces and three off-street spaceswould be gained. This project does not currently pro-pose to replace these long-term parking spacesbecause there is enough long-term parking availablein the project area. People currently parking for free

would need to pay to park, or they would need to usetransit. According to the Puget Sound RegionalCouncil's 2002 parking inventory study, 46.6 percentof parking spaces in the south end are utilized. Thereare more than five parking facilities in this area pro-viding more than 6,000 parking spaces. Using theestimated parking utilization rate in this area,approximately 2,800 spaces are available in this areaon a normal business day.

In the Pioneer Square area, 135 short-term parkingspaces would be removed. An additional 268 short-term spaces would be removed along the centralwaterfront area. Many businesses in these areas, par-ticularly retail shops, restaurants, and tourist destina-tions, rely on short-term parking for customer anduser access. Some parking mitigation options havebeen identified:

� Increase utilization of other existing parkingfacilities in the area.

� Lease an existing parking facility and convert itto short-term parking.

� Purchase property and build new short-term parking.

A formal parking mitigation plan for short-termparking losses in the Pioneer Square area and alongthe central waterfront will be developed and present-ed in the Final EIS. In the north end, parking lots inthe area have available capacity to help offset the lossof 40 parking spaces, so mitigation is not proposed.

Finally, if the options in either the north or south endwere constructed as part of the Surface Alternative,the total number of spaces removed would not beexpected to change compared with the numbers dis-cussed above.

8 If the Surface Alternative were built, what would itlook like?

In the Surface Alternative, Alaskan Way Viaductwould be replaced with a six-lane surface roadway that would combine SR 99 with the Alaskan Way sur-face street. Starting at S. King Street, SR 99 wouldmerge with Alaskan Way, splitting off again nearPine Street to climb toward the Battery Street


Tunnel. This alternative would change the corridorin several important ways.

With the viaduct gone, views to and from the water-front, currently obstructed by the viaduct, would beopened up for the first time since the early 1950s.From the Pioneer Square Historic District and fromthe commercial core, views to the west that are cur-rently dominated by the viaduct would instead focuson pier buildings along the waterfront, and then pastthose buildings to the Kitsap Peninsula, BainbridgeIsland, and the Olympic Mountains. Exhibit 9-8shows a simulation of the Surface Alternative lookingnorth near Yesler Way.

Looking back to downtown from the waterfront,views of the city's skyline would no longer be inter-rupted by the viaduct's two elevated lanes and numer-ous support columns. As a result, the waterfrontwould appear far more connected with the city than itdoes presently.

The area currently beneath the viaduct is visually clut-tered with parking and vertical support columns,always in shadow, and dominated by the elevatedstructure above. With the Tunnel Alternative, theAlaskan Way surface street would be changed toimprove the surface street and to improve the lookand feel of this waterfront area for the public.Improvements could include landscaping, a broad-ened waterfront promenade, sidewalks on the eastside of Alaskan Way, a landscaped trolley corridor, aparking and access lane along the waterfront, andbike lanes. Gone would be existing effects from theviaduct's height, scale, bulk, and its industrial con-crete design, which contrast with the visual characterof Pioneer Square Historic District, the central water-front, and parts of the commercial core.

Views south from Pike Place Market and VictorSteinbrueck Park to the waterfront would probablybe dominated by the roadway and traffic of SR 99 asit climbs from the waterfront to Battery StreetTunnel. In Belltown and on SR 99 north of BatteryStreet Tunnel, the overall character of the area wouldnot be affected much by this alternative.

Because this alternative would have neither a tunnelnor an elevated structure between S. King and PikeStreets, the combined Alaskan Way surface street/SR99 would carry far more traffic than the Alaskan Waysurface street does presently and more than the sur-face street would in any other alternative. Additionaltraffic along with the overall width of the six-laneroadway might reduce the potential for reestablishinga visual connection between the waterfront and thecity and contrast with the visual character of the cen-tral waterfront by making the corridor appear heavilyautomobile oriented.

South of S. King Street, two lanes, one in each direc-tion, would be added to accommodate additional traf-fic. Additionally, an overpass about half the height ofthe existing viaduct would connect SR 99 with S. Atlantic Street and S. Royal Brougham Way. Thesechanges would probably not alter the character of this area, which is dominated by Seattle's sports stadi-ums, industrial buildings, and Port of Seattle contain-er facilities.

Drivers traveling north and south along the water-front would no longer have the scenic views currentlyavailable from the viaduct roadway. Many pleasantviews would be available along the waterfront, includ-ing waterfront buildings and activities. Views stretch-ing from Elliott Bay to the Olympics and newlyrevealed views of the Seattle skyline would be avail-able for those not in vehicles.

9 How would noise or vibration levels change?

The Surface Alternative's noise levels would be theloudest during the early-morning, midday, andevening periods when drivers could travel near thespeed limit. Traffic noise would decrease by up to 4dBA in some locations compared to existing levels. Ina couple of other locations, traffic noise wouldincrease up to 5 dBA compared to existing 2002 lev-els. To the human ear, a 2- to 3-dBA increase is barelynoticeable. A 5-dBA increase in traffic noise is readilynoticeable.

The noise abatement criterion is 67 dBA for noise-sensitive outdoor uses at locations such as parks,

hotels, and residences. Existing traffic noiseapproaches or exceeds the FHWA traffic noise abate-ment criteria at 43 of the 48 sites modeled. Trafficnoise levels with the Surface Alternative wouldapproach or exceed the traffic noise abatement crite-ria at 42 sites. These sites include approximately4,490 residential units, 1,290 hotel rooms, and 120shelter beds. Nine of the sites are park or public openspaces, two are educational or childcare sites, andfive sites are commercial or other less noise-sensitiveuses. Modeled noise levels at specific locations maybe found in Exhibits 5-1 and 5-2 of Appendix F. Sixsites that are severely affected by noise for the year2030 existing facility would continue to be severelyaffected by the Surface Alternative.


Exhibit 9-8Surface Alternative Simulationat Jackson Street

Appendices D and E contains additional informationabout views.

Appendix F contains additional noise and vibration information.

Total noise levels at many of the sites would begreater than the predicted traffic noise level becausenon-traffic sound sources contribute substantially tothe total noise level in much of the corridor. Noisefrom other sources, such as aircraft, restaurants andother businesses, the bustle of sidewalks, construction,mechanical systems in buildings, alarms, and sirens,also contributes to the total noise environment.

Improvements to the Battery Street Tunnel wouldinclude the extension of the tunnel portals and instal-lation of jet fans to provide emergency and supple-mental ventilation. There are several residential usesnear the south portal of the Battery Street Tunnel.The jet fans will be designed not to exceed 57 dBA atthe nearest residential property line during normaldaytime operations. A level of 57 dBA is typical ofpeople talking from 10 feet apart. If the fans are to beoperated regularly during nighttime hours, they willbe designed not to exceed 47 dBA during thosehours.

The following mitigation measures were evaluatedfor their potential to reduce noise impacts from theSurface Alternative: traffic management measures,acquiring land as buffer zones or for construction ofnoise barriers or berms, realigning the roadway, andinstalling noise insulation for public use or nonprofitinstitutional structures. It is not feasible to mitigatetraffic noise impacts that would occur under theSurface Alternative because they are largely causedby traffic operating on the city street system ratherthan an individual limited-access facility.

The Surface Alternative would cause lower maximumvibration levels than the current viaduct, which focus-es vibrations from the elevated structure into areasaround the bases of support piers.

10 How would the Surface Alternative change charac-ter and land use in the project area?

Currently the viaduct blocks views between the water-front and neighborhoods to the east and restrictsoptions for land use and development-both underand adjacent to the elevated structure.

The Surface Alternative could affect land uses in thecorridor in several important ways. The current layoutof the central waterfront's streets, sidewalks, and openspace would be reconfigured in this alternative, possi-bly adding part of the area that's currently under theviaduct to the surrounding public open space (com-patible with the City of Seattle's central waterfrontplanning efforts). Additions might include featuressuch as landscaping, bike lanes, planted traffic andtrolley medians, and broadening the waterfront prom-enade.

Replacing the central portion of the viaduct with acombined SR 99/Alaskan Way surface street couldaffect land uses away from the waterfront as well.Without the viaduct, a scenic view would stretch fromthe edge of the commercial core to the OlympicMountains. A clear visual connection could be estab-lished between the waterfront and the city, and theway to the waterfront and back could be enhancedwith unobstructed sight lines, improved street cross-ings, and an extension of the City of Seattle's GreenStreets efforts to the waterfront on east-west streets.

In the Surface Alternative, Alaskan Way surface streetwould have three lanes in each direction-two morethan the Tunnel Alternative and the same number asthe Bypass Tunnel Alternative. Additionally, theamount of traffic on Alaskan Way would be fargreater in this alternative than in any other, owing tothe combining of Alaskan Way and SR 99. Together,the roadway width and increased traffic might limitthe sense of connection between the waterfront andthe city. Nevertheless, overall changes resulting fromthis alternative could make nearby buildings and landmore desirable for land uses that benefit from views,proximity to public open space, and foot traffic-possi-bly leading to new kinds of development in the proj-ect corridor.

Because the combined Alaskan Way/SR 99 in theSurface Alternative would accommodate far less traf-fic than the two roads do separately, the waterfrontwould experience heavier congestion than it doesnow. Many motorists would probably try to escape thistraffic by detouring to other nearby streets. On First

Avenue, on-street parking would be replaced with twoadditional travel lanes to accommodate extra traffic,potentially affecting sidewalk cafes and other busi-nesses that rely on a pleasant pedestrian environment(especially Pioneer Square). In general, the extra traf-fic, noise, exhaust, and congestion would make FirstAvenue a less desirable place to visit and do business,possibly making businesses less competitive.

About 720 parking spaces in the corridor would beremoved. South of S. King Street, new ramps wouldconnect SR 99 to S. Atlantic Street and S. RoyalBrougham Way. These would be partially located inthe Port of Seattle's container cargo facilities, reduc-ing the area used for container delivery, storage, andpickup. However, the ramps would also make it easi-er for trucks to move between the Port's facilities andboth SR 99 and I-5.

Added congestion on Alaskan Way surface streetwould also lengthen travel times on the north-southroute between the industrial area south of downtownSeattle and the Ballard/Interbay industrial area tothe north. In the northbound direction, travel timeswould increase during the PM Peak from 19 minutesfor the 2030 existing facility to 27 minutes. Increasedtravel times for trips between these two industrialareas makes this alternative less supportive of theirindustrial land uses than other alternatives, which donot reduce travel times.

11 How would the Surface Alternative affect parks,recreation, and open space facilities?

With the viaduct removed from the central water-front, views between the waterfront and the citywould no longer be blocked by the elevated structure;however, the width of the six-lane surface street alongwith the large volumes of traffic it would generate (byfar and away the most surface traffic of any alterna-tive) might reduce the potential for enhancing visualand physical connections between the waterfront andthe city.

One of the benefits of this alternative to parks andrecreational facilities is that a broad public open spacewould be created where SR 99 turns northeast to

The Land Use and Shorelines Technical Memorandumfound in Appendix G discusses this topic more extensivelyand looks at the alternatives with an eye toward theirconsistency with current local land use plans and policies.

Appendices H and N contain additional information aboutparks and recreation.

Historic Washington Street Boat Landing


climb to Battery Street Tunnel and the Alaskan Waysurface street turns west toward the waterfront.Located directly adjacent to the Seattle Aquariumand Waterfront Park and across Alaskan Way fromthe Pike Street Hillclimb, this space could be devel-oped as a waterfront park or plaza.

A new over-water pier would be built near the end ofS. Washington Street connecting to Colman Dock.The pier would remove Alaska Square, a small publicaccess and shoreline viewing area. Alaska Square iscurrently closed because the bulkhead supporting itis failing. Alaska Square could be replaced with side-walks and shoreline viewing near its current location.The new over-water pier would also require relocat-ing the Washington Street Boat Landing about 125feet west of its current location.

The Surface Alternative would modify the WaterfrontTrail, which is separated from the Alaskan Way sur-face street and shared by bicyclists and pedestrians.The separated, shared path would be extended southfrom S. Royal Brougham Way to just south of S.Atlantic Street. From S. Atlantic Street to Yesler Way,the Waterfront Trail would be moved from the eastside of E. Marginal Way/Alaskan Way to the westside. Between Yesler Way and Pine Street, the trailwould change from being a separated, shared bicycleand pedestrian pathway. Bicyclists would ride instriped lanes along the Alaskan Way surface street,and pedestrians could walk on sidewalks on the eastside of Alaskan Way or the waterfront promenadelocated on the west side of Alaskan Way. From PineStreet north, the Waterfront Trail would not beaffected. The Surface Alternative would result in theloss of parking spaces that are currently beneath theviaduct, possibly making parking somewhat more dif-ficult for some people visiting the waterfront.

12 How would the Surface Alternative affect neigh-borhoods and the people who live there?

The Surface Alternative would dramatically changethe character of the commercial core along the cen-tral waterfront. Removing the existing viaduct wouldtake away the shadowy area that now separates thedowntown portion of the neighborhood from the

waterfront. However, there would be more trafficlanes, more vehicles, and increased congestion alongAlaskan Way surface street. These conditions are notconducive for pedestrians and could substantiallydiminish the sense of connection created by the openviews of Elliott Bay. It is possible that the open feel of the area could attract more people who wouldwant to live and work in the area. However, it is alsolikely that increased congestion could make the arealess appealing.

In the north end of the project area, Aurora/SR 99 iscurrently a barrier for people and traffic movingbetween neighborhoods to the east and west. TheWidened Mercer improvements would benefit theUptown and South Lake Union neighborhoods bywidening the existing Mercer Street underpass andconstructing a bridge over Aurora Avenue N. atThomas Street. If the option to add traffic signalswere built, some east-west connections across SR 99might be improved; however, the signals would slowtraffic traveling on the new intersecting local streetsas well as Aurora/SR 99 and would generally increasecongestion in the area.

13 Would the Surface Alternative affect communityand social services?

The Surface Alternative would affect community andsocial services providers in the corridor in severalways. The CASA Latina Day Workers' Center (whichdispatches jobs for casual day laborers) is located nearthe south portal of the Battery Street Tunnel andwould be displaced. In the south, Alaskan Way surfacestreet would generally have more traffic congestionthan with the other alternatives. This would generallycreate more difficult driving conditions. In the down-town area, organizations providing social and commu-nity services would be hampered by overall conges-tion. For example, residents of the St. Martin dePorres homeless shelter are driven daily during peaktravel times to another social service organizationeach morning and then picked up each evening.Deliveries to service providers would be more diffi-cult, and volunteers would find it more troublesome

and time-consuming to provide support. Responsetimes by emergency services would also be increased.

14 What residences, businesses, or other propertieswould need to be acquired?

No residences would be affected. Up to 33 parcelswould be permanently acquired for the SurfaceAlternative. If these parcels are fully acquired, thetotal area obtained would be approximately1,759,000 square feet (40 acres). Additionally, about398,000 square feet along the eastern side ofTerminal 46 may be acquired for right-of-way needsor ferry holding. Up to 20 buildings would be modi-fied or displaced during construction, including 10commercial buildings, 9 industrial buildings, and FireStation No. 5. At this time, the number of businessesor employees that would need to be relocated isunknown; however, it is estimated that up to 581employees in the 20 buildings could be affected.Specific information about the number of businessesand employees requiring relocation will be developedas part of the Final EIS.

Of the 33 parcels that would potentially be acquired,23 are located in the southern section of the project,9 are located in the central section, and 1 is locatedin the north section. Additional parcels or buildingswould receive minor modifications, such as changesto driveways, parking, or fences, which would notalter their existing use. The lead agencies would workclosely with the affected businesses and properties tominimize the level of disruption.

15 How would the Surface Alternative affect historicresources?

The Surface Alternative would replace the viaductwith a surface roadway that would combine AlaskanWay surface street and SR 99. Gone with the viaductwould be much of the blocked views to and from his-toric buildings and neighborhoods. As with all alter-natives, old ramps connecting SR 99 with FirstAvenue would be removed, benefiting the surround-ing area. However, new ramps would connect SR 99to S. Royal Brougham Way and S. Atlantic Street (onthe south edge of the Pioneer Square neighborhood).


Appendices I and J contain additional information aboutneighborhoods.

Will the agencies help relocate properties that need to be

purchased for the project?

The lead agencies will provide relocation assistance andcompensation to the affected property owners and ten-ants as mitigation. Compensation will comply with theFederal Uniform Relocation Assistance and Real PropertyAcquisition Policies Act of 1970, as amended. Relocationassistance includes determining special needs and provid-ing referrals to comparable properties.

Appendix K contains additional information about proper-ties that would potentially be acquired.

Appendices L and N contain additional information abouthistoric resources.

These could affect their surroundings with trafficnoise and blocked views that could affect nearby his-toric buildings. Continuing into downtown, ramps atColumbia Street and Seneca Street would beremoved, eliminating the existing effects to the his-toric buildings around them.

Along the waterfront, the Washington Street BoatLanding pergola would be relocated approximately125 feet west of its current location to make way forthe Colman Dock ferry access road. In the PioneerSquare Historic District, the One Yesler Way buildingwould be in the way of a direct connection toWestern Avenue, but it could be picked up andmoved to an open site across the street. The SurfaceAlternative assumes two lanes are added on FirstAvenue through Pioneer Square. The additionallanes would require strengthening the areaways(spaces under sidewalks initially created whenPioneer Square streets were raised after the 1889fire) under the sidewalks, which could affect their his-toric qualities. Finally, the Battery Street Tunnel,another structure eligible for historic listing, wouldbe remodeled to make it safer. These updates mightchange the character of the tunnel portals. The tun-nel already intrudes on the basement of the CatholicSeamen's Club, which may be altered for the tunnelimprovements and is eligible for listing in theNational Register of Historic Places.

The existing viaduct is eligible to be listed in theNational Register of Historic Places. The Alaskan WaySeawall is also eligible. The potential historic status ofthese structures will be considered as part of the plan-ning process but is not expected to prevent theirreplacement. Replacement of the seawall is notexpected to affect any other historic resource in thecorridor.

As part of the planning and design of the SurfaceAlternative, measures would be taken to lessen theeffects it would have on historic buildings and neigh-borhoods. These measures might include designingnew structures to blend in with their historic sur-roundings, moving historic buildings instead of tear-ing them down, and documenting buildings and

structures that need to be removed (with photos, sur-veys, measurements, and notes) to help preserve thememory of Seattle's history for the future.

16 How would the Surface Alternative affect publicservices (such as police and fire)?

Public services would mostly be affected by changesin traffic patterns within the corridor. The SurfaceAlternative would cause many changes to travel pat-terns. The south and central portions of the corridorwould be congested, and travel times would increasesubstantially both on SR 99 and on adjacent citystreets. This would cause delays for all vehicles,including public service providers. The reliability ofthe corridor for emergency services would be worstduring peak travel times (during the morning andafternoon commute) and events at the stadiums. Theoverall congestion caused by the Surface Alternativewould cause delays for Fire Stations Nos. 5 and 10and for the West Precinct and East Precinct policestations. Other services like mail and garbage pickupwould also be delayed.

A couple of changes proposed for the SurfaceAlternative would improve emergency vehicle accessand response to the Battery Street Tunnel. TheBattery Street ramps would be closed to all trafficexcept for emergency vehicles, which would providethem direct access to the Battery Street Tunnel. Inaddition, improvements to the Battery Street Tunnelwould enhance the ability to fight fires in the tunnel,and additional exits from the tunnel would improveoverall safety.

North of the Battery Street Tunnel, effects to publicservice providers would be mixed. Mercer Streetwould be widened and would become a two-waystreet, and a bridge would connect Thomas Streetover the top of SR 99. The bridge at Thomas Streetand expanded Mercer would provide additional east-west traffic movements in this section of the corridor.However, additional congestion and delay is expectedat a couple of additional intersections due to theroadway changes. Therefore, traffic conditions in thenorth end would have improved street grid connec-

tions, although more congestion is anticipated with atwo-way Mercer Street.

17 How would the Surface Alternative affect the localand regional economy?

The Surface Alternative would combine traffic fromSR 99 and Alaskan Way surface street on a waterfrontsurface road. With more vehicles on fewer lanes, traf-fic would slow down, and it would take longer to getthrough the corridor than it would if the existing sys-tem were left in place.

The Surface Alternative would permanently displaceup to 20 buildings with approximately 581 employ-ees. If these businesses are not relocated within thecity, local sales, business and occupation (B&O), andproperty tax revenue might be lost. However, if dis-placed businesses leave Seattle but stay in the region,the new location would continue to collect B&O taxesand support the regional economy.

Under the Surface Alternative, approximately 720parking spaces would be removed. About 221 of these spaces are free long-term spaces underneath the viaduct south of S. King Street. Therefore, peoplecurrently parking for free would need to pay for long-term parking, use public transit, or find otherplaces to park. Most of the other spaces that would be removed, about 403, are short-term spaces inPioneer Square and the central waterfront projectarea. This short-term parking is used by customersand tourists in the AWV Corridor. Without mitiga-tion, the property displacements and loss of parkingspaces could affect the economic viability of business-es in these areas.

Quick and efficient distribution of goods and servicesis an important part of the health of a vigorous localand regional economy. The Surface Alternativewould improve connections to downtown Seattle atseveral major cross streets, but overall traffic conges-tion in the corridor would be worse. The Elliott andWestern ramps that provide a connection for theBallard/Interbay area would remain; however, itwould take longer for freight trucks to travel to andfrom the Ballard/Interbay area because the primary

Appendix O contains additional information about public services.

Appendix P contains additional information aboutEconomics.

Appendix Q contains additional information about air quality.


truck route would be along the combined SR99/Alaskan Way surface arterial. The SurfaceAlternative would provide improved connections tothe Duwamish area, Harbor Island, and SR 519. Thenew interchange at SR 519 would provide grade-sepa-rated access over the tail track, allowing vehicularaccess from the waterfront to SR 519 when freighttrains are present.

The option to connect both ramps to Elliott Avenuewould not make a significant difference to truck traf-fic. If the option to include signals at Thomas,Harrison, and Roy Streets is added in the north area,it could increase congestion and slowing, but mightimprove overall safety. Overall, future freight mobili-ty would be degraded compared to the 2030 existingfacility conditions. Associated freight operating andshipping costs would increase.

18 Would the Surface Alternative change air quality?

Under the Surface Alternative, concentrations of car-bon monoxide and particulate matter (PM10) wereestimated under peak traffic conditions for studyarea intersections (Exhibits 6 1, 6 2, and 6 3 inAppendix Q). The highest carbon monoxide concen-trations would occur under the Surface Alternativebecause of increased traffic congestion; however, thefuture pollutant concentrations would still be below(within) the National Ambient Air Quality Standards(NAAQS).

Daily pollutant emissions from traffic in the studyarea in 2030 were also estimated. Comparisonbetween existing study area emissions and the variousalternatives in 2030 demonstrates the trend towardscleaner operating vehicles for carbon monoxide,oxides of nitrogen, and hydrocarbons in 2030(Exhibit 6-4 in Appendix Q).

19 How would the Surface Alternative affect fish andwildlife species and their habitat?

One way the Surface Alternative would affect wildlifehabitat is by replacing the old seawall with a new one.The new concrete seawall would be constructed slight-ly landward of the existing seawall along the majority

of the corridor. In some areas, the existing seawallwould be removed, increasing the water volume in theimmediate area by an estimated 8,000 cubic yards.Like the old seawall, the basic structure in the aquatichabitat along the new seawall would consist of a verti-cal concrete wall with rock riprap placed at its basewhere needed to prevent erosion. Up above at streetlevel, urban habitat-mostly street trees and shrubs-would remain much the same as it currently is. Theexisting stormwater facilities that collect and conveywater from the viaduct are old and would be replacedwith new facilities using current design standards andtechnology, improving the quality of water dis-charged.

The vertical concrete seawall is poor intertidal habitatfor many species, including ESA listed species such asChinook salmon and bull trout. The Seattle water-front is a migration corridor and rearing area forjuvenile Chinook and other juvenile anadromoussalmonids. Juvenile salmon are commonly present atvarious protected locations near the water's surface inthe vicinity of the seawall during spring migration.Other fish species commonly observed in the shore-line area along the seawall include seaperch, baypipefish, shiner perch, sculpins, greenling, variousflatfishes, and a few lingcod. These fish would experi-ence the same basic habitat as they do today when thenew seawall is constructed. The habitat along the sea-wall is also occupied by a range of marine inverte-brates, such as red crab, hairy crab, coon-stripedshrimp, octopus, starfish, and anemones.

Between Pier 48 and Colman Dock, a new over-waterpier would be built to provide vehicle access to theColman Dock Ferry Terminal. The new pier wouldcover approximately 35,200 square feet of intertidalshoreline (areas that are exposed during low tides),including riprap, and shallow subtidal habitat (areasnormally covered by water). Under other piers alongthe waterfront, marine biologists observed thatmacro algae (a kind of seaweed, important for foodand habitat for aquatic animals) have a hard timegrowing in shade cast by the piers. The shade wouldprobably keep macro algae and other aquatic vegeta-tion from growing under the new pier.

Project planners and designers would work withresource agencies (like the Corps of Engineers) toaddress habitat that could be affected by shadingfrom the construction of the pier. These efforts couldinclude protecting an existing intertidal beach withan offshore berm or breakwater and creating newbeaches in open areas along the waterfront thatwould provide much-needed aquatic habitat alongSeattle's urban shoreline. This would give youngsalmon the protective shallow water habitat they needto grow and provide a corridor along the waterfrontin which adult salmon could migrate on their way toand from the Pacific Ocean. Other possibilities forrestoring more natural habitat characteristics wherepossible are also being studied.


Appendix R contains additional information about fishand wildlife.

Changes to Elliott Bay at S. Washington StreetBypass Tunnel

Exhibit 9-9

What is a BMP?

A Best Management Practice (BMP) is an action or struc-ture that reduces or prevents pollutants from entering thestormwater and degrading water quality.

The approaches for stormwater management aredescribed in Chapter 2.

20 Would the Surface Alternative change water quality?

The amount of impervious surface area would notincrease under the Surface Alternative. Incorporationof Best Management Practices (BMPs) into theSurface Alternative would improve the water qualityof runoff discharged from the project area comparedwith existing conditions. Rain running off the streetsand highways collects pollutants like zinc and copperthat reduce water quality and can be harmful toaquatic plants and wildlife. The Surface Alternativewould provide an overall reduction in total suspend-ed solids, zinc, and copper. The amount of pollutantswould decrease in the Duwamish River, Elliott Bay,and Lake Union and increase in Puget Sound due tothe greater volumes discharged at the West PointTreatment Plant.

The Battery Street Tunnel improvements include afire suppression system. In an emergency, it is possi-ble that runoff from this system could dischargedirectly into Elliott Bay, temporarily reducing dis-solved oxygen needed by aquatic plants and wildlife.These short-term impacts are allowed under State ofWashington laws.

The Convey and Treat Approach would decrease thevolume of stormwater that goes directly to Elliott Bayand increase the volume discharged to Puget Sound.According to the current design plans, the locationsof the outfalls would remain the same. The SurfaceAlternative could result in a net benefit to the envi-ronment compared to existing conditions.

21 How would the Surface Alternative change the soilconditions once the project is completed?

To meet earthquake standards, the soil would have tobe strengthened to ensure that it would not liquefy inan earthquake. A large part of the Alaskan WayViaduct project area is located on loose fill, soft sedi-ment, sand, and gravel (described in Chapter 3Question 2). The Surface Alternative's structuresmust be supported by soils that are stronger thanthese loose materials to withstand an earthquake. Inthe project area, piles or drilled shafts would need tobe installed 60 to 150 feet deep to reach the denseglacial soils that would support the facility.

The soils would be strengthened to reduce the seis-mic hazards and meet the earthquake standards. Soilscan be strengthened by using jet grouting or deepsoil mixing techniques. These techniques inject, mix,or replace the existing soil with cement grout tostrengthen the soils.

Soils would be strengthened around the new founda-tions of structures, under some proposed retainingwalls, and behind the seawall. The soils would prima-rily be strengthened in the south section and alongthe waterfront. The soils between Pine Street and theBattery Street Tunnel have sufficient strength and donot need to be improved. In the north section of theSurface Alternative, the Battery Street Tunnelimprovements may require some shallow founda-tions, which would displace a small amount of soil.The changes to the street grid would require soilexcavation to widen Mercer Street and fill to beplaced along Broad Street.

The extent of soil improvement behind the seawalldepends upon the type of seawall and depth to glacialsoils. Improvements behind the seawall are likely touse the jet grouting technique. From S. King Street toS. Washington Street, soil improvements behind theexisting sheet pile wall would be made to a depth ofabout 40 feet and a width of about 35 feet. Along thePile-Supported Gravity Wall from S. WashingtonStreet to Madison Street, soil improvements would bemade to a depth of about 40 feet and width of about65 feet. The Type A and Type B Seawalls are located

between Madison Street and Myrtle Edwards Park.Behind the Type B Seawall, the soil improvementswould be around 60 feet in width and 65 feet indepth. The soil improvements behind the Type ASeawall would improve approximately the first 40feet east of the seawall to a depth of about 55 feet.

22 Would the Surface Alternative change groundwa-ter flows?

Once the soil has been injected, mixed, or replacedwith cement grout, groundwater would not be able toflow as readily in these areas. However, since theimprovements are limited, overall groundwater flowin the watershed would not be substantially affectedby the project. Groundwater levels may change slight-ly, although the changes would probably be less thanthe natural fluctuations in groundwater levels thatalready occur.

23 Would the Surface Alternative create orremove any contaminated materials or sites?

The Surface Alternative would not create any newcontaminated materials or sites. This alternativewould result in removal of an estimated 741,000cubic yards of soil or material generated as spoilsduring construction. Of this amount, approximately351,000 cubic yards of potentially contaminated soilswould be removed and disposed of appropriately,which would benefit the project area. Removal of thecontaminated soil could reduce potential groundwa-ter contamination as well as the potential for expo-sure to workers on future excavation projects in thearea.

Appendix S contains additional information about water quality.

Appendix T contains more information about geology,soils, and groundwater.

Appendix U contains additional information about con-taminated materials.



Documents

Exhibit 9-1 · Exhibit 9-1.1 The liquefiable soils behind the seawall and under the relieving platform would be improved by strengthening them with cement grout. Similarly, a small