TRANSPORTATION TECHNICAL REPORT - web6.seattle.gov

DRAFT

TRANSPORTATION TECHNICAL REPORT

DENNY CENTRE

2014 FAIRVIEW AVENUE SDCI PROJECT #3021621

PREPARED FOR:

BOSA PROPERTIES

PREPARED BY:

6544 NE 61st Street, Seattle, WA 98115 ph: (206) 523-3939 fx: (206) 523-4949

APRIL 20, 2016

Denny Centre (SDCI Project #3021621) DRAFT Transportation Technical Report

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TABLE OF CONTENTS

1. INTRODUCTION ........................................................................................................................... 1 1.1. Project Description ................................................................................................................. 1 1.2. Study Area .............................................................................................................................. 1

2. AFFECTED ENVIRONMENT ....................................................................................................... 4 2.1. Roadway Network .................................................................................................................. 4 2.2. Traffic Volumes ..................................................................................................................... 7 2.3. Traffic Operations ................................................................................................................ 13 2.4. Traffic Safety ....................................................................................................................... 14 2.5. Parking ................................................................................................................................. 15 2.6. Transit .................................................................................................................................. 15 2.7. Non-Motorized Transportation ............................................................................................ 18 2.8. Freight .................................................................................................................................. 18

3. IMPACTS ...................................................................................................................................... 19 3.1. Roadway Network ................................................................................................................ 19 3.2. Trip Generation .................................................................................................................... 19 3.3. Trip Distribution and Assignment ........................................................................................ 25 3.4. Traffic Operations ................................................................................................................ 29 3.5. Site Access and Truck Loading ............................................................................................ 30 3.6. Safety ................................................................................................................................... 30 3.7. Parking ................................................................................................................................. 30 3.8. Transit .................................................................................................................................. 31 3.9. Non-Motorized Facilities ..................................................................................................... 31 3.10. Transportation Concurrency ................................................................................................. 31 3.11. Cumulative Transportation Impacts ..................................................................................... 32 3.12. Construction Traffic Impacts ............................................................................................... 33

4. MITIGATION ............................................................................................................................... 34 4.1. Short-Term Construction Mitigation .................................................................................... 34 4.2. Long-Term Mitigation ......................................................................................................... 35

5. SIGNIFICANT UNAVOIDABLE ADVERSE IMPACTS .......................................................... 36 REFERENCES

APPENDIX A – Level of Service Definitions

APPENDIX B – Mitigation Fee Calculations


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FIGURES

Figure 1. Site Plan .................................................................................................................................. 2 Figure 2. Vicinity Map and Study Area Intersections ............................................................................ 3 Figure 3. Existing (2015) Traffic Volumes - AM Peak Hour ............................................................... 9 Figure 4. Existing (2015) Project Traffic Volumes - PM Peak Hour .................................................. 10 Figure 5. Forecast (2021) Without-Project Traffic Volumes - AM Peak Hour ................................... 11 Figure 6. Forecast (2021) Without-Project Traffic Volumes - PM Peak Hour ................................... 12 Figure 7. Transit Service within Vicinity of Project Site ..................................................................... 17 Figure 8. Project Trip Distribution and Net Trip Assignment – AM and PM Peak Hours .................. 26 Figure 9. Forecast (2021) With-Project Traffic Volumes – AM Peak Hour ........................................ 27 Figure 10. Forecast (2021) With-Project Traffic Volumes – PM Peak Hour ....................................... 28

TABLES

Table 1. Study Area Intersections .......................................................................................................... 4 Table 2. Study Area Roadways .............................................................................................................. 5 Table 3. Level of Service Summary – Existing (2015) and 2021-Without-Project Conditions ........... 14 Table 4. Intersection Collision Summary ............................................................................................. 15 Table 5. Basline Trip Generation Rates, Equations and AVO Assumptions ....................................... 21 Table 6. Total Person Trips Generated by Denny Centre ..................................................................... 22 Table 7. Mode Split & Average Vehicle Occupancy for Local Neighborhood ................................... 23 Table 8. Person Trips by Mode of Travel ........................................................................................... 23 Table 9. Vehicle Trips Generated by the Proposed Denny Centre Project .......................................... 24 Table 10. Vehicle Trips Generated by Existing Site Uses ................................................................... 24 Table 11. Net Change in Vehicle Trips ............................................................................................... 24 Table 12. Level of Service Summary – 2021 Without- and With -Project Conditions ........................ 29 Table 13. Level of Service Screenlines – With Proposed Project ........................................................ 32 Table 14. Contribution to SDOT's Active Traffic Management Project .............................................. 35 Table 15. Denny Centre – Pro-Rata Share Contributions in South Lake Union .................................. 36


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1. INTRODUCTION This report presents the transportation impact analysis for the Denny Centre project in Seattle’s Denny Triangle neighborhood. This detailed transportation analyses was performed to support the project’s Addendum to the Draft and Final Environmental Impact Statement prepared for the Downtown Height and Density Changes.1 For simplicity, that document will be referred to as the “Downtown EIS.” This Transportation Technical Report includes new analysis specific to the proposed Denny Centre project, including detailed trip generation estimates, off-site traffic operations analyses, and parking analyses. The off-site analyses consider many infrastructure changes that have occurred or will occur, but that were not considered in the original Downtown EIS, primarily the Alaskan Way Viaduct Replacement project, that will affect traffic on Denny Way. The analyses also consider potential growth associated with the rezone proposed in the South Lake Union neighborhood, which were evaluated in the South Lake Union Height and Density Alternatives EIS,2 and considers the cumulative effects of other planned development project in the vicinity. This report also assesses the potential cumulative impacts associated with the planned expansion of the Washington State Convention Center (WSCC).

1.1. Project Description

The project site, at 2014 Fairview Avenue, is a triangular site bounded by Denny Way on the north, Fairview Avenue/Boren Avenue on the west, and Virginia Street on the east. The project would demolish an existing commercial building and surface parking lot on the site, and build a 42-story residential tower, retail space and five below grade parking levels. The project proposes to construct 442 residential units, 9,300 square feet (sf) of retail/restaurant space, parking for 308 resident vehicles, and 161 bicycle parking spaces for residents and commercial users. All site access would occur from a single driveway on Virginia Street. This driveway would also serve the 35-foot loading space. The site plan is shown on Figure 1. The site is currently occupied by a building with 22,590 leasable square feet with a Subway sandwich shop, dry cleaners, chiropractic health office, Michael’s Market, and other small retail spaces. The site has about 24 parking spaces to serve the uses in the building. These facilities would be eliminated by the project.

1.2. Study Area

The study area for this project focuses on intersections near the site as well as intersections along the Denny Way corridor adjacent to the site. Overall, five intersections were evaluated for this study and are listed in Table 1. Each intersection has been assigned an identification number that is used in all tables and traffic volume figures to improve the reader’s orientation. The study area intersections are shown on Figure 2.

1 City of Seattle Department of Planning and Development, Draft EIS completed November 2003; Final EIS completed

January 2005. 2 City of Seattle Department of Planning and Development, Draft EIS completed February 2011; Final EIS completed

April 2012.

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Figure 1

Site Plan

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Figure 2

Vicinity Map and

Study Area Intersections

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Table 1. Study Area Intersections

Int. # Intersection Name

1 Denny Way / Fairview Avenue

2 Denny Way / Minor Avenue (unsignalized)

3 Denny Way / Stewart Street

4 Fairview Avenue / Boren Avenue / Virginia Street

5 Boren Avenue / Stewart Street

Note: Each intersection’s identification number (Int #) is used in all tables and traffic

volume figures to improve the reader’s orientation.

All but one of the intersections are signalized; the exception is the Denny Way/Minor Avenue intersection, which has a stop sign controlling the southbound and northbound movements on Minor Avenue.

2. AFFECTED ENVIRONMENT This section describes the existing roadway network, traffic volumes, and traffic operations at the study intersections, parking conditions, safety, transit, non-motorized facilities, and freight in the site vicinity. It also describes how these conditions may change in the future without the proposed project. The proposed Denny Centre project is planned to be complete and occupied by the end of 2019; however, to be consistent with other analyses in the immediate area, and to specifically account for other large developments that are proposed for the area—including Amazon.com’s Rufus 2.0 project, Ninth & Stewart Mixed-Use Project, the Washington State Convention Center Expansion—future analyses were performed for year 2021 conditions. The Downtown EIS evaluated year 2020 conditions.

2.1. Roadway Network

2.1.1. Existing Roadways

The site is located just south of the South Lake Union neighborhood and north of downtown Seattle in the Denny Triangle neighborhood. Denny Way provides primary arterial access to the local and regional roadway network (Interstate 5 [I-5] and State Route 99 [SR 99]. The City of Seattle designates streets as principal arterials, minor arterials, collector arterials, and local access streets depending upon the street’s function in the roadway network. There are many arterial streets in the immediate site vicinity: Denny Way, Fairview Avenue, Virginia Street, Boren Avenue, and Stewart Street. Table 2 describes key roadways that serve the immediate site area. For reference, streets are assumed to be oriented in the east-west direction and avenues are assumed to be oriented in the north-south direction.


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Table 2. Study Area Roadways

Street Classification(s) 1 Lane Configurations

Non-Motorized and Transit Characteristics

Denny Way Principal Arterial

Minor Transit Street (east of 3rd Avenue)

Class II Pedestrian Street

2 travel lanes in each direction.

Left-turn pockets at some major intersections.

Parking not provided.

Sidewalks both sides.

Bus stops every 2-3 blocks.

Fairview Avenue N Principal Arterial

Minor Transit Street


1–2 travel lanes each direction. 2

Two-way center turn lane.

Parking on both sides.2

Sidewalks both sides.

Bus stops every 2 blocks.

Boren Avenue Principal Arterial

Minor Transit Street


2 travel lanes in each direction with left-turn lanes provided at intersections.

Parking not provided.

Sidewalks on both sides.


Virginia Street Minor Arterial west of Boren Avenue Local access street east of Boren Avenue

Major Transit Street (4th to 9th Avenue)

Two-way street between 9th Avenue and Avenue with two eastbound lanes and one westbound lane. Two-way street between Boren Avenue and Minor Avenue with one lane in each direction. One-way east-bound west of 9th Avenue.

Parking intermittently on both sides with time restrictions.


Sharrows provided.


Stewart Street Principal Arterial

Principal Transit Street (I-5 to 4th Avenue)

Class I Pedestrian Street

One way in southwest direction with 4 lanes during AM peak, 2 lanes remainder of day.

Parking intermittently on both sides with time restrictions.


Sharrows provided.

Designated Bicycle Route, east of 4th Avenue.

Bus stops every 2-3 blocks

1. Sources: City of Seattle, Arterial Classification Map (2003), Transit Classification Map (2006), Major Truck Street Map (2003),

Pedestrian Street Classification Map (2006).

2. Parking is allowed in the outside lanes during off-peak times, resulting in one travel lane in each direction with a center two-way left-turn

lane. Parking restrictions are in place in the southbound direction during the AM peak period, and in the northbound direction during the

PM peak period, providing two travel lanes in peak directions during these times.


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2.1.2. Future Improvements

Extensive transportation improvements are under construction or have recently been completed in the neighborhood. The improvements that would affect traffic flow and operations in the site vicinity are:

Alaskan Way Viaduct Replacement Project (Bored Tunnel) – The North Portal of the Bored Tunnel will be located west of Aurora Avenue N just north of Harrison Street. Once through traffic on SR 99 is directed into the new tunnel, the segment of Aurora Avenue N between Harrison Street and Denny Way will be reconstructed to have two through lanes plus a transit-only lane and left turn lanes at intersections (seven lanes to-tal). Three street crossings of Aurora Avenue N will be re-established at John Street, Thomas Street, and Harrison Street, each controlled by a new traffic signal. New ramps to and from SR 99 north of the neighborhood will be created at Harrison Street; new ramps to and from SR 99 south will be created at Republican Street with the northbound off-ramp connecting to Dexter Avenue N, and the southbound on-ramp connecting to 6th Avenue N. This project is expected to change future travel patterns on portions of Denny Way by changing where traffic must access SR 99 and providing new crossings of Aurora Avenue N. The bored tunnel is expected to open in 2018 and the surface street improvements completed in 2020.

Mercer Corridor Project – The Mercer Corridor project was completed in 2015. The Mercer East project improved Mercer Street, Valley Street, 9th Avenue N, Westlake Avenue N, and Fairview Avenue N. It converted the former one-way couplet to focus all through traffic onto two-way Mercer Street. A second project, Mercer West, widened Mercer Street under Aurora Avenue N, and allows two-way traffic operations west to Elliott Avenue W.

CBD Dynamic Signal System Upgrade – The Seattle Department of Transportation (SDOT) has embarked on this project, which will upgrade the signal system for all downtown intersections. As part of that effort, new signal phasing and timing protocols are being developed for various subareas. The analysis performed for this study assumes SDOT’s preliminary recommendations for signal timing and phasing. It is likely that these timing assumptions will change as planning and design progress.

Adaptive Traffic Signals for Mercer Street and Denny Way Corridors – SDOT plans to upgrade the signal system along the Mercer Corridor, which is Phase 1 of the neighborhood’s Adaptive Signal Control program. Adaptive signal control systems continually monitor traffic flow and adjust signal operations to accommodate changing conditions. Most of the infrastructure for this system is already in place as part of the Mercer Corridor improvements. The new signal improvements would upgrade the controllers and establish the signal timing algorithms. As part of Phase 2, signal equipment (including new detection at all intersections) would be upgraded along the Denny Way corridor.

Pedestrian signal at Denny Way/Minor Avenue – Seattle City Light’s Denny Substation project plans to install a new pedestrian-only signal at the intersection of Denny Way/Minor Avenue as part of its project, which would vacate Pontius Avenue between Denny Way and John Street.

These projects are expected to be completed about the same time the proposed Denny Centre is completed. Some shifts in City-wide traffic patterns could occur with these projects, but the effect near


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the project site would be minor. The proposed signal at Denny Way/Minor Avenue would likely increase pedestrian crossings at that location, but would not affect vehicle movements since they would still be unsignalized. Traffic signal timings and phasing were optimized for the other intersections within the study area to account for the planned signal improvements. One planned change to the general area is the elimination of the westbound contra-flow lane on Olive Way between Minor Avenue and Terry Avenue in order to accommodate an eastbound transit lane. Westbound traffic has been reassigned to Stewart Street for the future analysis conditions. According to the City of Seattle’s 2016-2021 Adopted Capital Improvement Program3 there are no other major projects in the immediate site vicinity that could affect intersection geometry or traffic volumes prior to the project opening in 2019.

2.2. Traffic Volumes 2.2.1. Existing Traffic Volumes

Existing traffic volumes used in this analysis were counted in March through May 2015 and December 2015 during both the AM and PM peak hours. Locations where construction projects forced full or partial intersection closures, historical counts from traffic studies published in 2013 or 2014 were used and balanced with the 2015 count data for those locations. The existing (2015) AM and PM peak hour traffic volumes are shown on Figure 3 and Figure 4, respectively.

2.2.2. Future Traffic Volume Forecasts

The future 2021 traffic volumes were estimated using background growth rates originally derived for the Transportation Technical Report for the Ninth & Stewart Mixed Use Project,4 and Rufus 2.0 (Amazon) EIS Addendum. 5 These analyses determined that future development in both the downtown area as well as South Lake Union neighborhood would increase traffic volumes on most streets in the study area by 0.5% per year through the year 2021. That growth rate accounts for smaller developments in the area. Added to that is traffic associated with full build out of nearby projects such as; Amazon.com’s Rufus 2.0 project, the Ninth & Stewart Mixed-Use Project,6 the 1821 Boren Avenue (Hill7)7 project, the 1800 Terry project,8 the 1007 Stewart project,9 the 1812 Boren (Tilt49) project10, Children’s Hospital Building Cure11 and 25 other projects in the area that would generate project traffic that could impact the study intersections. Planned changes to the roadway network that would impact circulation patterns in the area assumed to be in place for the future conditions. This includes elimination of the westbound contraflow lane on Olive Way between Minor Street and Terry Avenue. Existing and future pipeline traffic was reassigned to alternate routes throughout the roadway network. In addition, in 2021 when Link Light Rain is ex-

3. City of Seattle, 2016. 4 Heffron Transportation, Inc., January 2014. 5 Rufus 2.0 (Amazon) EIS Addendum, Transportation Technical Report, Heffron Transportation, Inc. August 9, 2012. 6 Traffic volumes associated with the most-common hotel operating scenario (Scenario E) were used in this analysis. 7 Transportation Technical Report for the Edison Project (now known as “Hill7”), Heffron Transportation, Inc., July 6,

2012. 8 Traffic Impact Study for 1800 Terry Ave Residential Development, Transportation Engineering Northwest, July 21, 2006. 9 Transportation Technical Report for the 1007 Stewart Street Project (Draft), Heffron Transportation, Inc., January 23,

2014. 10 Transportation Technical Report for the Tilt49 1812 Boren Avenue Project, Heffron Transportation, Inc. April 28, 2014. 11 Heffron Transportation, Inc., DRAFT Transportation Technical Report for Building Cure (DPD Project #3019542), 2016.


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tended to Northgate it is assumed that all buses currently using the Downtown Seattle Transit Tunnel would be removed. There are about 150 buses during the peak hours that operate through the DSTT. The future traffic volumes for the study area intersections include these rerouted buses. Further information about the future transit changes are described in Section 2.6. The 2021 weekday forecast traffic volumes for the without-project conditions are shown on Figure 5 for the AM peak hour and Figure 6 for the PM peak hour.

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Existing (2015) Traffic Volumes

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Figure 4

Existing (2015) Traffic Volumes

PM Peak Hour

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Figure 5

Forecast (2021) Without-Project

Traffic Volumes - AM Peak Hour

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Forecast (2021) Without-Project

Traffic Volumes - PM Peak Hour

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2.3. Traffic Operations

Level of service (LOS) is a qualitative measure used to characterize traffic operating conditions. Six letter designations, “A” through “F,” are used to define level of service. LOS A is the best and repre-sents good traffic operations with little or no delay to motorists. LOS F is the worst and indicates poor traffic operations with long delays. The City of Seattle level of service standards are evaluated through its Transportation Concurrency Policy (which is described later in this report). The City does not have adopted intersection level of service standards; however, project-related intersection delay that causes an intersection to operate at LOS E or F, or increases delay at an intersection that is projected to oper-ate at LOS E or F without the project, may be considered a significant adverse impact. The City may tolerate delays in the LOS E or F range for minor movements at unsignalized intersections where traffic control measures (such as conversion to all-way-stop-control or signalization) are not applicable or desirable. Appendix A includes level of service thresholds and definitions for unsignalized and signalized intersections per the 2010 Highway Capacity Manual (HCM).12 Levels of service for the study area intersections were determined using the Synchro 9.1 analysis software, and signal information obtained from SDOT and verified with field observations. Because of limitations of the HCM 2010 methodology, which include the unusual signal phasing that the City uses at some of the study area intersections, level of service results are reported using the Synchro methodology. As previously noted, SDOT plans to update signal timings in the CBD, and the future levels of service reflect preliminary timing plans. Table 3 summarizes the existing and 2021-without-project AM and PM levels of service for study area intersections. As shown, all of the study area intersections do or would operate at LOS E or F in 2021 without the proposed project in either the AM or PM peak hour. Many of these are clustered around the Interstate 5 access points and connecting arterials. As noted, the intersection at Denny Way/Fairview Avenue N/Boren Avenue N is expected to improve in the future, which is primarily related to assumed changes in signal operations. Turns from Minor Avenue onto Denny Way would also operate at LOS E or F conditions and any increase to traffic along Denny Way would increase the delay on these approaches. The proposed pedestrian signal would not affect vehicle operations.

12 Transportation Research Board, 2010.


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Table 3. Level of Service Summary – Existing (2015) and 2021-Without-Project Conditions

AM Peak Hour Conditions PM Peak Hour Conditions

Map 2015 (Existing) 2021 w/o project 2015 (Existing) 2021 w/o project

ID 1 Intersection LOS 2 Delay 3 LOS Delay LOS Delay LOS Delay

1 Denny Way / Fairview Avenue N D 35.7 F 84.6 C 30.7 D 54.8

2 Denny Way / Minor Avenue4

Northbound Approach Southbound Approach Westbound Left Turn

F F B

52.8 53.7 11.0

F F B

230.3 152.71

3.10

C C B

22.6 24.7 10.3

E F B

36.4 52.0 12.1

3 Denny Way / Stewart Street C 33.9 F 128.30 D 36.9 E 60.6

4 Fairview Avenue N / Virginia Street / Boren Avenue

E 68.2 D 39.3 C 28.2 C 30.0

5 Stewart Street / Boren Avenue D 42.1 E 79.0 C 24.2 C 25.1

Source: Heffron Transportation, Inc., 2016. Level of service performed using Synchro 9.1 methodology. Future conditions assume optimized

signal timings.

1. All intersections are keyed to the traffic volume figures with an intersection number.

2. Level of service.

3. Average seconds of delay per vehicle.

4. This intersection is unsignalized.

2.4. Traffic Safety

Collision data obtained from SDOT for the study intersections were assessed to determine if there are any traffic safety conditions that could impact or be impacted by the proposed project. The City data—reflecting the four-year period between January 1, 2012 and December 31, 2015 are summarized in Table 4. Historically, unsignalized intersections with five or more collisions per year and signalized intersections with 10 or more collision per year have been considered high collision locations (HCLs) by the City. Intersections are also considered high collision locations if there are five or more pedestrian or cyclist collisions in the preceding three years. The Denny Way /Stewart Street intersection meets this threshold based on the data reviewed. This intersection has been highlighted as a location for pedestrian improvement needs as discussed in Section 2.7 Non-Motorized Transportation of this report. In addition, a pedestrian signal is planned at the Denny Way/Minor Avenue intersection, which could reduce the number pedestrian crossings at other locations along Denny Way, such as at Stewart Street. SDOT staff conducts an annual analysis of high collision locations to define which locations should be reviewed. The 2015 High Collision Location List was reviewed for this analysis and none of the study intersections are listed. No fatalities were reported at any of the study area intersections during the four year study period.


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Table 4. Intersection Collision Summary

Number of Collisions by Type

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Signalized

Denny Way Stewart Street 0 1 5 0 3 4 5 3 21 5.3

Stewart Street Boren Avenue 0 0 7 1 1 4 4 1 18 4.5

Denny Way Fairview Avenue 0 0 3 0 0 5 2 4 14 3.5

Virginia Street Boren Avenue 0 0 2 0 0 0 1 0 3 0.9

Unsignalized

Denny Way Minor Avenue 0 2 0 2 7 5 0 3 19 4.8

Source: City of Seattle Department of Transportation, Collision data for the period 01/01/2012 through 12/31/2015.

a. ‘Other’ collisions included vehicle hitting an object, improper movement, or collision diagram not available.

2.5. Parking

There is no on-street parking allowed adjacent to the site on Denny Way, Fairview Avenue, or Boren Avenue. There is parallel parking allowed on Virginia Street. Those spaces have a 4-hour limit and require payment at a pay station. The west portion of the site is currently occupied by a surface parking lot that has approximately 24 spaces. This lot provides parking for the existing commercial uses on the site.

2.6. Transit

Transit service to the study area is provided by King County Metro, Sound Transit, and Community Transit. King County Metro provides bus and streetcar service, Sound Transit provides light rail and bus service, and Community Transit provides bus service. Within a general vicinity of the site, there are 14 transit stops serving over 40 bus routes. There is transit stops with shelters located along the site frontages on Fairview Avenue and Denny Way. Detailed information about routes and transit stops in the area are shown on Figure 7. It is noted that transit service in downtown Seattle is continually changing as new routes and services are added or eliminated; the data on the graphics reflect service as of April 2016. An extension of Sound Transit’s North Link light rail system is now in operation which connects downtown Seattle to the University of Washington at Husky Stadium. The link will extend to Northgate by 2021. An eastward extension to Bellevue and Overlake is proposed to be completed by 2022. The Convention Place Station (CPS) in the Downtown Seattle Transit Tunnel (DSTT) will eventually be eliminated since the light rail operations to the University District have begun. Buses that use the DSTT will be phased out of the tunnel and rerouted to surface streets; by 2021 when light rail is extended to Northgate, all buses are expected to be out of the DSST. There are about 150 buses during the peak hours that operate through the DSTT. The future traffic volumes for the study area intersections include these rerouted buses.


- 16 - April 20, 2016

SDOT has recently converted general purpose lanes on Westlake Avenue to transit only and business access lanes. In addition, the streetcar operates on Westlake Avenue with stops for northbound and southbound travel about two blocks east of the site. The streetcar operates seven days a week (Monday-Thursday 6:00 A.M. to 9:00 P.M., Friday-Saturday 6:00 A.M. to 11:00 P.M., and Sunday 10:00 A.M. to 7:00 P.M.) at 15-minute headways (time between consecutive arrivals) during all hours of operation.

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Transit Service Within

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1 Route provided byKing County Metro

14 Routes provided byKing County Metro,Sound Transit, andCommunity Transit

8 Routes provided byKing County Metro

South Lake Union Streetcar1 Route provided byKing County Metro

Route 8

Note: Route numbers provided for the transitstops closest to the site.

Routes 63, 64, 70,

71, 72, 73, 83, 309,

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2 Routes provided byKing County Metro


- 18 - April 20, 2016

2.7. Non-Motorized Transportation

All roadways in the immediate site vicinity have sidewalks on both sides of the street. All of the signal-ized study intersections have marked crosswalks and pedestrian signals. A new pedestrian-only signal is planned to be installed at the Denny Way/Minor Avenue intersection as part of Seattle City Light’s Denny Substation project. The project site is entirely within the High Priority Area for pedestrian improvements as identified in the Seattle Pedestrian Master Plan.13 (This area is established based on the potential for pedestrian demand, equity and corridor function.) This plan also lists streets that are part of the “Urban Village Transit Network” where high volumes of pedestrians exist and pedestrian improvements should be prioritized. Near the site, these include Fairview Avenue, Virginia Street, most of Stewart Street, and Olive Way. The Seattle Pedestrian Master Plan includes a process for determining scores for pedestrian safety (or comfort level) along roadways and roadway crossings and is used to compare areas and prioritize po-tential pedestrian projects. “It is meant to reflect the quality of the physical pedestrian environment along different roads in Seattle.”14 In addition, the Tier 1 score levels indicate the highest opportunity for improvement. There are a few areas within the study area that have received these high scores. “Tier 1 Crossing the Roadway” score areas include:

Denny Way/Stewart Street/Yale Avenue area Denny Way/near Yale Avenue and Pontius Avenue

There are many bicycle facilities in the site vicinity, including bicycle lanes and lanes that are marked with “sharrows,” indicating that motorists should share the lane with bicyclists. A “sharrow” is a shared-lane pavement marking that is placed in the roadway lane to highlight the shared space; however, unlike a bicycle lane it does not delineate a particular part of the roadway that a bicyclist should use. Stewart Street is marked with sharrows and is a signed bicycle route. Near the site; Virginia Street is also marked with sharrows. The city’s Seattle Bicycle Master Plan15 identified cycle tracks on Stewart Street, 7th Avenue and Pike Street. These are part of a large study evaluating potential bike improvements in the downtown core area, which includes design and analysis, determining how these cycle tracks would affect existing functions on the streets, including vehicle lanes, transit lanes and parking. Since no specific recommendations have yet been made, the existing lane configuration on Stewart Street was assumed for traffic analysis.

2.8. Freight

The Seattle Comprehensive Plan called for the designation of a network of Major Truck Streets to serve as primary routes for the movement of goods and services. Most streets in the study area are classified as arterials and are considered to be truck routes, although trucks that travel west of 8th Avenue into the Downtown Traffic Control (DTC) Zone are governed by the size and time restrictions. These re-strictions pertain to vehicles over 30-feet long, which are restricted in this zone Monday through Satur-day from 6:00 A.M. to 7:00 P.M., unless special permission is obtained. Over-legal loads are not permit-

13 City of Seattle, September 2009. 14 Seattle Pedestrian Master Plan, City of Seattle, September 2009.


- 19 - April 20, 2016

ted in this zone from 6:00 A.M. to 7:00 P.M. Monday through Friday without special permits.16 The Seattle Municipal Code also prohibits large trucks (over 30-feet long or over 32,000 pounds) from using Denny Way between Western Avenue and Olive Way, and Boren Avenue and Boren Avenue South during the commuter peak periods (7:00 to 9:00 A.M. and 4:00 to 6:00 P.M.).17

3. IMPACTS This section describes the transportation impacts of the proposed project. These were compared to the future without project conditions, which reflect year 2021 with existing uses on the Denny Centre site. Comparing the net difference between the without and with project conditions allows the specific impacts of site development to be quantified. Transportation impacts are also compared to those presented in the Downtown EIS. It is noted that this analysis considers year 2021 conditions, whereas the Downtown EIS evaluated year 2020 conditions.

3.1. Roadway Network

The proposed project would improve the pedestrian areas surrounding the site with widened sidewalk areas, planter strips and gathering areas. A full access driveway would be located along Virginia Street. Curb bulbs would be provided along Virginia Street to maintain on-street parking spaces. No new roads or streets would be constructed with the project, and no alley or street vacations are proposed.

3.2. Trip Generation

3.2.1. Project Trips

The number of trips generated by the Denny Centre project was determined using the recommended methodology in the Institute of Transportation Engineers (ITE) Trip Generation Handbook.18 ITE recognizes that development projects located in dense urban environments generate fewer trips than those in suburban settings. The new Handbook states:

Most data presented in the Trip Generation Manual data volumes [sic] are vehicle-based and have been collected at low-density, single-use, suburban developments with little or no transit service, limited bicycle access, and little or no convenient pedestrian access. These sites are called baseline sites because they are the starting points for vehicle trip generation estimation. The analysis needs to adjust baseline vehicle trip generation estimates to correctly estimate trip generation for a site

Surrounded by compact urban development; Consisting of a mix of complementary land uses; Served by public transit; That attracts walking and bicycling trips; That prices on-site parking; and In an area with high vehicle occupancy as a result of an area-wide transportation

demand management program or preferential treatment for ridesharing. 16 City of Seattle Ordinance 108200 Section 11.14.165 Downtown Traffic Control Zone, 2010.

(http://www.seattle.gov/transportation/dtczmap.htm), March 25, 2016 Update. 17 Seattle Municipal Code 11.60.120. (www.municode.com/library/wa/seattle/codes/municipal_code?nodeId=13857) 18 Institute of Transportation Engineers, 3rd Edition, August 2014.


- 20 - April 20, 2016

Most of the special attributes listed above apply to projects in the site’s neighborhood; therefore, the following approach recommended in the Trip Generation Handbook was used to estimate trips for each mode of travel:

1. Estimate the baseline vehicle trips using data from the Trip Generation Manual.19

2. Convert the baseline vehicle trips to baseline person trips using baseline mode shares and vehi-cle occupancy rates for each land use (note, baseline vehicle occupancy rates are those inherent in the ITE rates).

3. Determine the appropriate mode of travel and vehicle occupancy for the subject site based on its characteristics and context.

4. Calculate person trips by mode of travel using the local mode of travel factors for the site.

5. Convert the person trips by vehicle into adjusted vehicle trips using the local vehicle occupancy rates for the site.

Baseline Trip Generation Factors

Table 5 summarizes the baseline trip generation rates, equations and average vehicle occupancy (AVO) factors used to estimate the proposed project’s person trips.

19 Institute of Transportation Engineers [ITE], 9th Edition, 2012.


- 21 - April 20, 2016

Table 5. Basline Trip Generation Rates, Equations and AVO Assumptions

Land Use (ITE Land Use Code)

ITE Baseline Trip Generation Equation or Rate a

Baseline Average Vehicle Occupancy (AVO)

Apartment (220) – Rental dwelling units located within the same building with at least three other dwelling units, for example, quadraplexes and all type of apartment buildings. Low rise, mid-rise and high-rises are included.

Daily 6.65 trips/unit 1.20 b

AM Peak Hour 0.51 trips/unit 1.20 b

PM Peak Hour 0.62 trips/unit 1.20 b

Shopping Center Retail (820) – Uses such as neighborhood centers, community centers, regional centers and super regional centers. These can be comprised of a composite of many types of uses such as traditional retail stores, restaurants, banks, post offices, health clubs, and others. Because of the small size of the proposed retail, average rates were used.

Daily 42.70 trips/1,000 sfgla 1.20 c

AM Peak Hour 0.96 trips/1,000 sfgla 1.20 c

PM Peak Hour 3.71 trips/1,000 sfgla 1.20 c

a. Source: Institute of Transportation Engineers (ITE) Trip Generation, 9th Edition, 2012.

T = trips during time period, X = size of use in 1,000 square feet of leasable area for retail.

b. AVO rates for suburban apartments surveyed for ITE is estimated to be 1.20 persons per vehicle.

c. No vehicle occupancy data are available for the Shopping Center (Land Use Code 820) in Trip Generation; however, ITE data avail-

able for other retail uses indicate occupancy rates range from 1.17 (for a hardware store) to 1.46 (for a discount store). For this analy-

sis, an AVO rate of 1.2 persons-per-vehicle was assumed.

Internal Trips

In addition to trips to and from a site, the total number of trips generated by a mixed-use development includes “internal trips,” or trips made between different uses on the site. For example, a trip that a resident makes at lunchtime to a local retail shop is calculated in the trip generation estimates for both the residential and the retail uses. Chapter 6 of the Trip Generation Handbook20 is devoted to estimating trip generation for multi-use developments, and provides a methodology to estimate the number of in-ternal trips that can be expected for specific mixes of uses. This method is based on the types and sizes of various land uses. The more balanced the mix of uses, the higher the percentage of internal trips. Developments with a predominance of one type of use (e.g., mostly office, or mostly residential) typi-cally have lower percentages of internal trips. ITE’s methodology to determine internal trips has four steps:

1. Determine the number of person trips expected to be generated by each land use as if each was on a separate site.

2. Determine the number of internal trips based on internal capture rates presented in the Trip Generation Handbook.

3. Balance the number of internal trips to and from all land uses at the site. 4. Total the resulting number of internal trips and calculate the percentage of internal trips.

20 Institute of Transportation Engineers, 3rd Edition, August 2014.


- 22 - April 20, 2016

Person Trips

The estimated person trips generated by the Denny Centre project are summarized in Table 6. Internal trips among the uses are estimated to account for about 4% of the daily trips, 1% of the AM peak hour trips, and 4% of the PM peak hour trips. The total number of person trips that would be external to this site is estimated at about 3,850 per day, with about 280 person trips in the AM peak hour and about 355 person trips in the PM peak hour.

Table 6. Total Person Trips Generated by Denny Centre

Daily AM Peak Hour PM Peak Hour

Person Trip Summary Size Trips In Out Total In Out Total

Apartment (220) 442 units 3,530 54 217 271 214 115 329

Retail (LU 820) 9,300 sf 480 7 4 11 20 21 41

Total All Person Trips 4,010 61 221 282 234 136 370

Internal Trips 160 2 2 4 7 7 14

% Internal Trips 3.8% 1.4% 3.8%

Total External Person Trips 3,850 59 219 278 227 129 356

Source: Heffron Transportation, Inc. April 2016. Trips estimated using procedures in the ITE Trip Generation Handbook, 2014.

Mode of Travel and Local Vehicle Occupancy

After the number of person trips was estimated, the person trips were separated by mode of travel based on the mode-split percentages appropriate for each type of use in the area. The resulting person trips made by vehicle were converted to vehicle trips using the locally-derived vehicle occupancy rate. These assumptions are described below for each land use type. Residential Mode-of-travel data for the residential component of the site were derived from ‘Journey-to-Work’ survey results from the year 2010 Census compiled by the PSRC. From these surveys, results for residents living in Transportation Analysis Zones (TAZs) 106, 107, 108, and 109 (the zones including and surrounding the project site) were used. A local AVO rate of 1.10 was applied for the residential uses. Retail Retail uses that would occupy the commercial space are expected to attract the majority of customers from neighborhood residents and employers, including the uses within the building. Of the external trips, it was assumed that 20% of the retail trips, including those by customers or employees, would be by private vehicle. There are no data regarding the AVO rate for local retail; therefore, the baseline rate described above (1.20 for retail) was applied. Table 7 summarizes the AVO and mode-split percentage assumptions that were applied to the person trips for each land use. Table 8 summarizes person trips by mode of travel for the Denny Centre project.


- 23 - April 20, 2016

Table 7. Mode Split & Average Vehicle Occupancy for Local Neighborhood

Local AVO Mode of Travel

Land Use Type Rate for Area Walk & Bike Transit Trips Vehicle Trips

Residential 1.10 51% 15% 34%

Retail 1.20 75% 5% 20%

Source: Heffron Transportation, Inc., April 2016.

Table 8. Person Trips by Mode of Travel

Project Component and % of Daily AM Peak Hour Trips PM Peak Hour Trips

Type of Trip by Mode Trips Trips In Out Total In Out Total

Apartment (LU 220)

Walk or Bicycle Trips 51% 1,750 27 109 136 106 57 163

Transit Trips 15% 510 8 32 40 31 17 48

Person Trips by Vehicle 34% 1,190 18 75 93 72 39 111

Total 100% 3,450 53 216 269 209 113 322

Retail (LU 820)

Walk or Bicycle Trips 75% 300 5 2 7 14 12 26

Transit Trips 5% 20 0 0 0 1 1 2

Person Trips by Vehicle 20% 80 1 1 2 3 3 6

Total 100% 400 6 3 9 18 16 34

Total Person Trips

Walk or Bicycle Trips 2,050 32 111 143 120 69 189

Transit Trips 530 8 32 40 32 18 50

Person Trips by Vehicle 1,270 19 76 95 75 42 117

Total 3,850 59 219 278 227 129 356


Vehicle Trips for Proposed Project

Vehicle project trips were determined by applying the local AVO rates to the person trips by vehicle generated by each land use. The total vehicle trips for the Denny Centre project are summarized in Table 9. The cumulative trips generated by all the land uses is estimated at about 1,140 vehicle trips per day, with about 86 trips during the AM peak hour and 106 trips during the PM peak hour.


- 24 - April 20, 2016

Table 9. Vehicle Trips Generated by the Proposed Denny Centre Project

Assumed Daily

Vehicle AM Peak Hour Vehicle Trips PM Peak Hour Vehicle Trips

Land Use Size Trips In Out Total In Out Total

Apartment 442 units 1,080 16 68 84 65 36 101

Retail 9,300 sf 60 1 1 2 3 2 5

Total 1,140 17 69 86 68 38 106

Source: Heffron Transportation, Inc. April 2016. Estimated using procedures in the ITE Trip Generation Handbook, 2014.

3.2.2. Existing Site Trips

The existing site is occupied by a commercial building with 22,590 leasable square feet and a parking lot with 24 spaces. The existing building accommodates a mix of offices, services, retail, and restaurant uses. To encompass these uses, data in ITE Trip Generation for Shopping Center retail (Land Use Code 820) was used. This is a conservative approach since the trip rates for the existing individual uses may be higher than what is provided for the combined Shopping Center rate. Although the site is well served by transit and experiences substantial pedestrian traffic, it also has free surface parking that provides for convenient customer access. Therefore, vehicle trips were assumed to represent 35% of the existing trips to the site (compared to 20% in the future when no customer parking is provided). Table 10 summarizes the vehicle trips generated by the existing uses on the site, which are estimated to generate about 340 vehicle trips per day with about eight during the AM peak hour and 29 during the PM peak hour.

Table 10. Vehicle Trips Generated by Existing Site Uses

Assumed Daily

Vehicle AM Peak Hour Vehicle Trips PM Peak Hour Vehicle Trips

Land Use Size Trips In Out Total In Out Total

Existing Uses 22,590 sf 340 4 4 8 14 15 29

Source: Heffron Transportation, Inc. April 2016.

3.2.3. Net Change in Vehicle Trips

The net change in vehicle trips is summarized in Table 11. As shown, the proposed project is anticipated to generate 800 net new vehicle trips per day, with 79 net new vehicle trips in the AM peak hour and 77 net new vehicle trips in the PM peak hour.

Table 11. Net Change in Vehicle Trips

Daily AM Peak Hour PM Peak Hour

Land Use Trips In Out Total In Out Total

Proposed Project 1,140 17 69 86 68 38 106

Existing Uses -340 -4 -4 -8 -14 -15 -29

Net Change 800 13 65 78 54 23 77



- 25 - April 20, 2016

3.3. Trip Distribution and Assignment

Trip distribution patterns for the Denny Centre project were determined based on information provided in the South Lake Union Height and Density Alternatives Draft EIS 21 and the City of Seattle’s Concurrency Director’s Rule 5-2009.22 The trip distribution pattern is shown on Figure 8. The project-generated trips were assigned to the roadway network based on the patterns described. The assignments considered the one-way street system and the proposed site access. The vehicular project trip assignments and distribution percentages are shown on Figure 8 for the AM and PM peak hours, respectively. The Denny Centre traffic volumes were added to the 2021-without-project traffic volumes. The 2021-with-project traffic volumes are shown on Figure 9 for the AM peak hour and Figure 10 for the PM peak hour.

21 City of Seattle Department of Planning and Development, February 2011. Page 3.13-55. 22 City of Seattle Department of Transportation, Transportation Concurrency Project Review System, Director’s Rule 5-

2009, Effective April 13, 2009.

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Project Trip Distribution and Net Trip Assignment

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Forecast (2021) With-Project

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- 29 - April 20, 2016

3.4. Traffic Operations

Levels of service for study area intersections were calculated using the 2021-with-project traffic volumes and the methodologies described earlier in this report. Table 12 shows the results of the analysis for the AM and PM peak hours, respectively. Levels of service for 2021-without-project conditions are shown for comparison. The results show that most locations are estimated to operate at LOS E or F in the future without or with the proposed project. The project would not increase the delay at any signalized location by more than two seconds. The left-turn and through movements on Minor Avenue at Denny Way are estimated to experience significant delay during the AM peak hour in the future without the proposed project. Although Seattle City Light plans to install a new traffic signal at this location, it is planned to be a pedestrian-only signal and would not improve vehicle operations. The left turns and through movements from the stop signs would be the most difficult movement and any traffic added to this intersection can contribute to additional delay. However, the left-turn and through movements from the stop signs have alternative routes that would allow the movements to occur with assistance of a traffic signal (at Denny Way and Fairview Avenue). Therefore, no mitigation is recommended for this unsignalized intersection. If needed, SDOT could restrict movements from the stop sign to right turns only which could improve the operations to LOS D during the AM peak hour. To help improve the other intersections in the corridor it is recommended that the Denny Centre project pay a pro-rata share towards the Denny Way Adaptive Traffic Signal project. The pro-rata share costs are described later in the Mitigation section of this report.

Table 12. Level of Service Summary – 2021 Without- and With -Project Conditions

AM Peak Hour Conditions PM Peak Hour Conditions

Map Without-Project With-Project Without-Project With-Project

ID 1 Intersection LOS 1 Delay 2 LOS Delay LOS Delay LOS Delay

1 Denny Way / Fairview Avenue N F 84.6 F 86.2 D 54.8 E 56.4

2 Denny Way / Minor Avenue4

Northbound Approach Southbound Approach Westbound Left Turn

F F B

230.3 152.71

3.10

F F B

271.9 227.7 13.3

E F B

36.4 52.0 12.1

E F B

35.8 65.7 12.6

3 Denny Way / Stewart Street F 128.30 F 129.4 E 60.6 E 61.5

4 Fairview Avenue N / Virginia Street / Boren Avenue

D 39.3 D 39.4 C 30.0 C 31.4

5 Stewart Street / Boren Avenue E 79.0 F 80.9 C 25.1 C 25.9

Source: Heffron Transportation, Inc., April, 2016.

1. All intersections are keyed to the traffic volume figures with an intersection number.

2. Level of service.

3. Average seconds of delay per vehicle.

4. This intersection is unsignalized.

The Downtown EIS did not evaluate the near-site intersections except for the signalized intersections located along Denny Way. It predicted that all but one of the signalized intersections on Denny Way between 6th Avenue and Stewart Street would operate at LOS F in the future during both the AM and PM peak hours. Therefore, the results in this analysis are consistent with those in the Downtown EIS.


- 30 - April 20, 2016

3.5. Site Access and Truck Loading

The proposed site would have one vehicle driveway for the parking garage located on Virginia Street. Analysis of the 2021-with-project conditions indicates the site access driveway would operate at LOS A during both the AM and PM peak hours. No on-site loading would be required for the project. However, the project proposes to provide one 35-foot loading area accessed from the driveway on Virginia Street.

3.6. Safety

The Downtown EIS did not evaluate potential safety impacts. Based on statistical trends, higher traffic and pedestrian volumes tend to relate to a higher number of collisions. Improvements in the near site vicinity are planned for previously identified needs. The project is not expected to result in a significant adverse impact to safety conditions.

3.7. Parking

The Downtown EIS predicted substantial displacement of parking due to redevelopment, most of this would be from lost surface parking lots. It also noted increased demand for on-street parking, and the potential loss of bus layover areas if they are incompatible with new development. Specific impacts related to the Denny Centre project are described below.

Site Parking

The project would provide parking for 308 vehicles in a below-grade parking garage. Residential parking would primarily be used for vehicle storage during most days since a minority of the residents would use their vehicle for a daily commute. Many residents may not own a car at all. The proposed parking supply represents a ratio of 0.70 spaces per unit. The 2010 Census compiled data about vehicle ownership, and showed that renter-occupied residences in the site’s neighborhood ranged from 0.53 vehicles per unit (census tract 72.00) to 0.78 vehicles per unit (census tract 73). Therefore, the proposed on-site supply is within an acceptable range to accommodate the residential parking demand. All on-street parking in the site vicinity is controlled with time limits and pay stations, and there is no residential parking zone (RPZ) available for building residents. Therefore, if additional parking is needed residents would need to arrange for off-street parking elsewhere. The project would not provide any on-site parking for the commercial spaces. The few retail customers who would drive and park at the site would likely need to use on-street parking in the site vicinity. Guests of residents would be able to use the on-street parking. No overflow parking from the residential uses is expected.

Displaced Parking

The project would eliminate a parking lot on the site which currently has 24 spaces. The elimination of on-site parking is not expected to adversely affect parking conditions in the neighborhood since the parked vehicles are associated with the existing uses that would also be removed by the project.

On-Street Parking

There is currently on-street parking adjacent to the site on Virginia Street. Curb bulbs would be added along the frontage to bracket the ends of the legal parking spaces. It is recommended that parking


- 31 - April 20, 2016

durations be decreased from 4-hours to 2-hours limits once the site is redeveloped and has commercial uses that require higher parking turnover.

3.8. Transit

The Downtown EIS evaluated the potential rezone effects to transit travel time and transit layover. However, it did not evaluate the potential impact to transit capacity or service needs. The number of transit riders generated by the Denny Centre project was described previously in the Trip Generation section. It is expected that the project would generate about 40 transit trips during the AM and PM peak hours. Overall, the increase in riders is not expected to adversely affect transit service. There are existing bus stops with shelters on Denny Way and Fairview Avenue adjacent to the site.

3.9. Non-Motorized Facilities

The proposed project is expected to increase pedestrian activity in the area (persons walking, bicycling and taking transit to and from the site) by about 1,820 non-motorized trips per day, with approximately 165 non-motorized trips occurring during the AM peak hour and 175 during the PM peak hour. The City of Seattle’s Land Use Code would require that the project provide 130 bicycle parking spaces. However, the project proposes to exceed these requirements and provide 161 long-term bicycle parking spaces in the building. As previously described, all frontages sidewalks would be widened with planting areas and gathering places. The proposed sidewalks would have adequate capacity to accommodate the forecast pedestrian volumes. No adverse impacts to the non-motorized network are expected.

3.10. Transportation Concurrency

The City of Seattle developed a Transportation Concurrency policy as part of its Comprehensive Plan,23 which was updated with the more recent Director’s Rule 5-2009. Within the transportation concurrency policy, the City has defined 30 screenlines, each of which encompasses one or more arterials in the city. Screenline analysis is a transportation-planning tool that groups key arterials of a transportation network together to measure the operating conditions of a corridor. For example, the Ship Canal functions as a screenline to measure north-south travel north of downtown Seattle. The City has established a level of service (LOS) standard for each screenline, which is measured by the volume-to-capacity ratio (v/c ra-tio). The project passes concurrency if the v/c ratio with the addition of a proposed project’s traffic is lower than or equal to the LOS standard for the screenline. Three screenlines were evaluated for the project, the Ship Canal/Aurora Avenue N (Screenline 5.13), the Ship Canal/University/Montlake Bridges (Screenline 5.16) and South of Lake Union (Screenline 8.00). The most recent official measurements of the screenline capacities were performed in 2008. The level of service standards and the volume-to-capacity (v/c) ratios are presented in Table 13. The new project trips were added to the 2008 City traffic counts. With the project, the v/c ratios for the screenlines evaluated would remain below the established LOS standards. Therefore, transportation concurrency would be met for this project.

23 City of Seattle, 1994.


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Table 13. Level of Service Screenlines – With Proposed Project

Screenline Number

Location

Direction

2008 Capacity

2008 Traffic Count a

Project Trips b

Total Volume across

screenline

With Project

v/c ratio c LOS

Standard d

5.13 Ship Canal/Aurora Avenue N

NB 5,100 4,472 2 4,474 0.88 1.20

5.13 Ship Canal/Aurora Avenue N

SB 5,100 3,756 4 3,760 0.74 1.20

5.16 Ship Canal/ University/ Montlake Bridges

NB 4,030 3,833 3 3,836 0.95 1.20

5.16 Ship Canal/ University/ Montlake Bridges

SB 4,070 3,571 7 3,578 0.88 1.20

8.00 South of Lake Union

EB 6,000 4,509 14 4,523 0.75 1.20

8.00 South of Lake Union

WB 3,600 3,020 8 3,028 0.84 1.20

Source: City of Seattle DPD Director’s Rule 5-2009, Approved 4/10/09 (Attachment C).

a. Data reflect most recent official measurement of screenline volumes and capacities from 2008.

b. Derived using the trip origin and destination matrices provided by the City.

c. v/c = volume-to-capacity ratio. It equals the 2008 traffic count+ project trips, divided by the 2008 capacity.

d. Level of service standard, reported as a v/c ratio, which was established by the City of Seattle Ordinance #117383.

3.11. Cumulative Transportation Impacts

The transportation analysis presented herein accounts for the traffic generated by many planned devel-opment projects that have not yet been constructed or occupied. As described earlier, traffic volumes were forecast to the year 2021 by applying a growth rate to existing traffic volumes to account for smaller developments, and specifically adding traffic associated with full build out of over 30 planned development projects. Therefore, the analysis accounts for the cumulative impacts associated with known projects. One potential project that was not specifically included is the future expansion of the Washington State Convention Center (WSCC). The WSCC Draft EIS24 evaluated the proposed WSCC Addition, which could add approximately 1.3 million sf to the existing WSCC. Preliminary analysis indicates that this could include approximately 250,000 sf of new exhibition space, 120,000 sf of meeting rooms, a 60,000 sf ballroom space, 19 truck bays, no on-site King County Metro bus layover bays, and structured parking for up to 800 additional vehicles. It is the intent of the WSCC to begin construction of the Addition by 2017, and be open for business in 2020. The WSCC EIS also evaluated the potential for co-development including towers for office and/or residential uses.

24 Draft Environmental Impact Statement for the Washington State Convention Center Addition, (Washington State

Convention Center, February 26, 2016).


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The number of trips generated by the WSCC Addition will be related to the types of events. Typically, morning trips would be highest for a large, locally-focused breakfast meeting. Afternoon trips would be highest for a consumer show that also draws from the local region. National conventions would generate the fewest trips. The trip generation estimates for the WSCC EIS show it is expected that the largest events could generate about 430 AM peak hour trips and 570 PM peak hour vehicle trips. Co-development on the site could add another 300 trips during the peak hours depending on the use, size, and number of parking spaces provided for it. The vast majority of trips would arrive and depart using regional highways (Interstate 5 and SR 99), and the Stewart Street, Howell Street, and Olive Way corridors. Truck traffic generated by the WSCC could affect Fairview Avenue and Boren Avenue. The WSCC Addition would add some delay to area intersections on days when there are events. However, it would not change the conclusions or recommended mitigation for the Denny Centre project.

3.12. Construction Traffic Impacts

The Downtown EIS did not address specific impacts related to construction activity. When Denny Centre is under construction, it is anticipated that construction workers would arrive at the construction site prior to the AM peak period and depart either prior to or after the PM peak period, depending upon specific work schedules. The number of construction workers would vary by construction stage, but in general the number of workers would be highest during the finishing stages of the building. Before the on-site parking garage is complete (and certified for occupancy); construction workers could increase the demand for parking at nearby commercial parking lots. For most urban projects, the most noticeable construction-related traffic impacts are likely to occur during demolition of existing uses and excavation for subterranean parking and foundations. The amount of material to be excavated from the Denny Centre site is estimated to be about 50,000 cubic yards (cy). The material is assumed to expand to about 65,000 cubic yards when it is excavated and loaded into a truck (“fluff” factor of 1.3). Assuming that each dump truck with trailer can carry about 20 cubic yards of material, the excavation would generate a total of about 3,250 truck-loads or 6,500 truck trips (3,250 empty trucks in plus 3,250 full trucks out). It is expected that the loading rate would be 8 to 12 trucks per hour, or up to 24 truck trips (12 in and 12 out) per hour. This work could last for several months. The number of daily and peak hour truck trips is less than the completed project would generate. Another construction phase that would result in high levels of truck activity would occur during foun-dation work for the building, which can require continuous concrete pours. Because of peak restrictions on truck activities in the Downtown core, any continuous pour operations would likely occur on a weekend. During continuous pours or other concrete work, the project could generate up to 50 concrete truck loads per hour resulting in 100 truck trips per hour (50 in and 50 out). These intense operations are typically completed in one day. Other materials, such as steel, lumber, drywall, windows, and other building supplies, are expected to be trucked to the site as needed, but deliveries and truck trips would not typically be concentrated in such short times as they would during the excavation and concrete stages of the work. It is expected that most construction trucks would access the downtown area via Interstate 5, and they would be directed to use the Denny Way or Stewart Street and Boren Avenue between I-5 and the site. During some stages of the work, lane closures may be required for utility work or to stage and load/unload trucks.


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The project site is subject to the City’s newly-enacted Construction Hub Coordination Program.25 This program was developed to provide additional pre-construction planning, and then to respond to and re-solve construction-related impacts that may be created by multiple public and private projects in the same vicinity. Program requirements that will need to be met by the contractor are described in Section 4.1 below.

4. MITIGATION The transportation impacts of the proposed Denny Centre project are consistent with those identified in the Downtown EIS. The following section presents mitigation measures for both the short-term construction impacts and long-term impacts to the transportation system.

4.1. Short-Term Construction Mitigation

SDOT has designated the Denny Triangle as a Construction Hub within the City’s Construction Hub Coordination Program. This program was developed to provide additional pre-construction planning, and then to respond to and resolve construction-related impacts that may be created by multiple public and private projects in the same vicinity. Prior to beginning work that could impact SDOT right-of-way; the contractor will be required to submit the following information to SDOT for review and approval of necessary permits:

Haul Route Plan;

Project Schedule by phase and by frontage (in SDOT’s template spreadsheet);

Traffic Control Plan for work on an arterial street or within high impact area;

Pedestrian Mobility Plan noting how construction methods would comply with Direc-tor’s Rule 1-2011 by frontage and by phase;

Construction worker transportation and parking plan, noting measures taken to reduce construction worker trips (e.g., transit passes or carpooling programs) and noting where contractor parking would occur;

Confirmation of project information outreach to businesses, residents and stakeholders within a one block radius of the project; and

Confirmation of notification of construction impacts to businesses, residents and stakehold-ers within a one-block radius of the project at least 72 hours prior to beginning work.

25 Seattle Department of Transportation, Construction Hub Coordination Program Brochure, July 2014, and SDOT website

at http://www.seattle.gov/transportation/hubRequirements.htm, accessed November 14, 2014.

http://www.seattle.gov/transportation/hubRequirements.htm


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4.2. Long-Term Mitigation

4.2.1. Denny Way Corridor Improvements

As part of its Next Generation Center City ITS Implementation Plan26, the SDOT is planning to upgrade many traffic signals along the Denny Way corridor as Phase 2 of the neighborhood’s Adaptive Traffic Signal program. This would upgrade signal equipment, vehicle detection, traffic cameras, dynamic mes-sage signs, and fiber communication. SDOT has estimated that the Denny Way element would upgrade 14 intersections at a total cost of about $4.3 million, which averages to about $307,500 per intersection to be upgraded.27 The project’s pro-rata share of the cost of improving affected intersections was estimated as summarized in Table 14. The project’s estimated mitigation contribution would be $6,255.

Table 14. Contribution to SDOT's Active Traffic Management Project

Intersection

Proposed Project

PM Peak Hour Trips

Future 2021 PM Peak Hour

w/o Project Volumes

Pro-rata Share Percentage a

Preliminary SDOT Cost Estimate

Project Contribution

Estimate

Stewart St/Denny Way 26 3,075 0.84% $307,500 $2,580

Boren Ave/Stewart St 18 2,455 0.73% $307,500 $2,240

Denny Way/Fairview Ave 17 3625 0.47% $307,500 $1,435

Total $6,255

a. Pro-rata share = Project Trips ÷ (Future No Build Volumes + Project Trips). April 2016.

4.2.2. Transportation Mitigation Payment

The City of Seattle has established a transportation mitigation payment system for development in and around the South Lake Union neighborhood. 28 Mitigation payments help fund planned transportation improvements identified in the South Lake Union Transportation Plan. The Plan identifies improve-ments to automobile infrastructure, bicycle facilities, pedestrian walkways, and transit facilities. Although this project is located outside of the South Lake Union mitigation fee area, other projects in the Denny Triangle have made voluntary payments of a pro-rata fee based on assignment of project traffic and their share of improvement projects that have not yet been built. Table 15 outlines the pro-rata share contributions for Denny Centre, which would have an estimated pro-rata contribution of $1,155. The final fee should be determined prior to building permit. A summary of the detailed calculations for each project listed by the City for this area is shown in Appendix B.

26 Seattle Department of Transportation, October 2013. 27 E-mail from Adiam Emery of SDOT, July 9, 2014. Cost estimate included equipment, installation, design, construction

management, and contingency. 28 Tip 243 (previously Client Assistance Memorandum (CAM) #243), City of Seattle, DPD, Updated October 4, 2012.


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Table 15. Denny Centre – Pro-Rata Share Contributions in South Lake Union

City of Seattle Capital Improvements/Locations Pro-Rata Share

Contribution

Auto Traffic Projects

Surface Streets East of Aurora $39

Transit Projects

TSP emphasis on Fairview Avenue Corridor $1,516

Pro-Rata Contribution Total $1,555

Source: Based on PM peak hour information from the South Lake Union Transportation Study, and The Transpo Group. Data for the Denny Centre Project by Heffron Transportation, Inc., April 2016.

5. SIGNIFICANT UNAVOIDABLE ADVERSE IMPACTS

The proposed Denny Centre project would not create any additional significant adverse impacts beyond those already identified in the Downtown EIS.


April 20, 2016

REFERENCES City of Seattle Department of Planning and Development, Transportation Concurrency Project Review System, Director’s Rule 5-2009, Effective April 13, 2009.

City of Seattle Department of Transportation; Collision data, obtained for period from January 1, 2012 through December 31, 2015.

City of Seattle, Arterial Classification Map, 2003.

City of Seattle, Transportation Strategic Plan, October 2005.

City of Seattle; 2016-2021 Proposed Capital Improvement Program.

City of Seattle; Bicycle Master Plan, April 2014; Bike Master Plan Implementation Plan 2015-2019; October 17, 2014.

City of Seattle; Comprehensive Plan, 1994.

City of Seattle; Major Truck Street Map, 2003.

City of Seattle Ordinance 108200 Section 11.14.165 Downtown Traffic Control Zone, 2010. (http://www.seattle.gov/transportation/dtczmap.htm) and Seattle Municipal Code 11.062.120.

City of Seattle; Seattle Pedestrian Master Plan; September 2009.

City of Seattle; Transit Classification Map, 2006.

Community Transit; Transit website, April 2016.

Dames & Moore, Draft Environmental Impact Statement for the Proposed Expansion Washington State Convention & Trade Center, April 2, 1996.

Heffron Transportation, Inc., Transportation Technical Report for the Edison Project (now known as “Hill7”), July 6, 2012.

Heffron Transportation, Inc. Transportation Technical Report for Tilt49 – 1812 Boren Avenue, April 28, 2014.

Heffron Transportation, Inc., Rufus 2.0 (Amazon) EIS Addendum, Transportation Technical Report, August 9, 2012.

Heffron Transportation, Inc., Transportation Technical Report for the Ninth & Stewart Mixed Use Project, January 2014.

Heffron Transportation, Inc., Transportation Technical Report for the 1007 Stewart Street Project June 2, 2014.

Institute of Transportation Engineers; Parking Generation, 4th Edition; 2010.

Institute of Transportation Engineers; Trip Generation Manual, 9th Edition; 2012.

Institute of Transportation Engineers; Trip Generation Handbook, 3rd Edition; August 2014

http://www.seattle.gov/transportation/dtczmap.htm


April 20, 2016

King County Metro, website, April 2016.

LMN Architects, Washington State Convention Center Expansion Feasibility Study Draft Report, August 15, 2013.

Parsons Brinkerhoff, Downtown Height and Density EIS – Parking Technical Report, March 2002.

Puget Sound Regional Council, Journey-to-Work survey results from the 2010 Census.

Seattle Department of Transportation, Next Generation Center City ITES Implementation Plan, October 2013.

Seattle Department of Planning and Development; Tip #243 (previously named Client Assisted Memorandum (CAM) #243).

Seattle Department of Planning and Development; Transportation Concurrency Project Review System, Director’s Rule 5-2009; Effective April 13, 2009.

Seattle Department of Planning and Development; Draft and Final Environmental Impact Statement prepared for the Downtown Height and Density Changes; Draft EIS completed November 2003; Final EIS completed January 2005.

Seattle Department of Planning and Development; South Lake Union Height and Density Alternatives EIS, Draft EIS completed February 2011; Final EIS completed April 2012.

Sound Transit; Transit website, April 2016.

Transportation Research Board; Highway Capacity Manual; 2010.

Transportation Engineering Northwest, Traffic Impact Study for 1800 Terry Ave Residential Development, July 21, 2006.


APPENDIX A

LEVEL OF SERVICE DEFINITIONS


Levels of service (LOS) are qualitative descriptions of traffic operating conditions. These levels of ser-vice are designated with letters ranging from LOS A, which is indicative of good operating conditions with little or no delay, to LOS F, which is indicative of stop-and-go conditions with frequent and lengthy delays. Levels of service for this analysis were developed using procedures presented in the Highway Capacity Manual (Transportation Research Board, 2010). Level of service for signalized intersections is defined in terms of delay. Delay can be a cause of driver discomfort, frustration, inefficient fuel consumption, and lost travel time. Specifically, level of service criteria are stated in terms of the average delay per vehicle in seconds. Delay is a complex measure and is dependent on a number of variables including: the quality of progression, cycle length, green ratio, and a volume-to-capacity ratio for the lane group or approach in question. Table A-1 shows the level of service criteria for signalized intersections from the Highway Capacity Manual.

Table A-1. Level of Service Criteria

Level of Service Average Delay Per Vehicle General Description

A Less than 10.0 Seconds Free flow

B 10.1 to 20.0 seconds Stable flow (slight delays)

C 20.1 to 35.0 seconds Stable flow (acceptable delays)

D 35.1 to 55.0 seconds Approaching unstable flow (tolerable delay—occasionally wait through more than one sig-nal cycle before proceeding.

E 55.1 to 80.0 seconds Unstable flow (approaching intolerable delay)

F Greater than 80.0 seconds Forced flow (jammed)

Source: Transportation Research Board, Highway Capacity Manual, 2010.

For unsignalized two-way-stop-controlled, all-way-stop-controlled, and roundabout intersections, level of service is based on the average delay per vehicle. The level of service for a two-way, stop-controlled intersection is determined by the computed or measured control delay and is defined for each minor movement. Delay is related to the availability of gaps in the main street's traffic flow, and the ability of a driver to enter or pass through those gaps. The delay at an all-way, stop-sign (AWSC) controlled intersection is based on saturation headways, departure headways, and service times. Delay at roundabouts is based on entry flow rates and flow rate capacity. Table A-2 shows the level of service criteria for unsignalized intersections from the Highway Capacity Manual.

Table A-2. Level of Service Criteria for Unsignalized Intersections

Level of Service

Average Delay (seconds per vehicle)

A Less than 10.0

B 10.1 to 15.0

C 15.1 to 25.0

D 25.1 to 35.0

E 35.1 to 50.0

F Greater than 50.0

Source: Transportation Research Board, Highway Capacity Manual, 2010. .

APPENDIX B

MITIGATION FEE CALCULATION

Proportional Share Estimate

Project Name: Denny CentreNon-SLU Only Growth Impact vs. Non-SLU Only Growth Cost

South Lake Union Transportation Study Capital Improvements

Auto Traffic Projects Traffic Bike Pedestrian TransitRecommended

ShareTwo-Way Mercer/Narrow Valley Concept

1+2 Construct 2-way Mercer St/2-lane Valley St 0.00% 100% 0.00% 68,200,000$ 23.0% 76.8% 12,046,848$ -$ -$ 3 Signal @ Dexter/Republican 0.21% 100% 0.21% 250,000$ 86.0% 76.8% 165,120$ 345.38$

Mercer/Fairview/I-5 Ramps4 Mercer/Fairview Improvements 0.06% 100% 0.06% 430,000$ 86.0% 76.8% 284,006$ 179.51$ -$

Harrison St. East of Aurora5 Harrison from Fairview to 5th 0.03% 100% 0.03% 750,000$ 23.0% 76.8% 132,480$ 38.68$ 38.68$

Two-way traffic on 9th and Westlake6 2-way Westlake and 9th 0.00% 100% 0.00% 835,000$ 86.0% 76.8% 551,501$ -$ -

Eastlake Avenue7 Allow SB Eastlake left-turns at NB I-5 Express Lanes 0.00% 100% 0.00% 250,000$ 86.0% 76.8% 165,120$ -8 Signal @ Eastlake/Thomas 0.00% 100% 0.00% 250,000$ 86.0% 76.8% 165,120$ -$ -$ 9 Signal @ Eastlake/Republican 0.00% 100% 0.00% 250,000$ 86.0% 76.8% 165,120$ -$ -$

Auto Traffic Project Sub-Total 71,215,000$ - 76.8% 13,675,315$ 563.58$ 38.68$

Bicycle ProjectsImprove around the lake bike facilities

10 Fairview bicycle lanes 0.00% 76.62% 0.00% 275,000$ 75.0% 53.3% 109,931$ -$ -$ 11 Modify Fairview near Eastlake for ped/bike access 0.00% 76.62% 0.00% 1,200,000$ 75.0% 53.3% 479,700$ -$ -$

Bike Routes12 Sign Lakeview bike route 0.00% 76.62% - 1,000$ 75.0% 53.3% 400$ -13 Sign Eastlake bike route 0.00% 76.62% 0.00% 2,000$ 75.0% 53.3% 800$ -$ -$ 14 Sign commonly used bike routes 0.00% 76.62% 0.00% 6,000$ 75.0% 53.3% 2,399$ -$ -$

Maintain/Improve Dexter as a north/south bicycle corridor Average Bike Project Impact15 Improve Dexter bike corridor 0.00% 76.62% - 2,000$ 75.0% 53.3% 800$ -

Bike Project Sub-Total 1,486,000$ 75.0% 53.3% 594,029$ -$ -$

Pedestrian ProjectsCascade Neighborhood Ped Improvements

16 Add stop signs at Thomas and Harrison intersections 0.00% 76.62% 0.00% 8,000$ 96.1% 39.5% 3,037$ -$ 17 Widen sidewalks around Cascade Park 0.00% 76.62% 0.00% 140,000$ 96.1% 39.5% 53,143$ -$

Improve Denny Way Pedestrian Environment & I-5 Crossing18 Improve Denny/I-5 crossing 0.00% 76.62% - 2,750,000$ 96.1% 39.5% 1,043,886$ -19 Improve five Denny intersections 0.00% 76.62% - 580,000$ 96.1% 39.5% 220,165$ -

Pedestrian Project Sub-Total 3,478,000$ 96.1% 39.5% 1,320,231$ -$

Transit ProjectsCreate transit emphasis/TSP on Fairview Ave

20 Transit Signal Priority on Fairview @ Denny 4.23% 51.95% 2.20% 110,000$ 68.6% 87.7% 66,201$ 1,453.55$ 1,453.55$ 21 TSP and queue jump on Fairview @ Harrison 0.12% 51.95% 0.06% 110,000$ 68.6% 87.7% 66,201$ 40.71$ 40.71$ 22 TSP at Fairview @ Mercer 0.06% 51.95% 0.03% 110,000$ 68.6% 87.7% 66,201$ 21.74$ 21.74$ 23 TSP on Fairview @ Valley 0.00% 51.95% 0.00% 110,000$ 68.6% 87.7% 66,201$ -$ -$

Construct Proposed SLU Streetcar/Trolley Route -$ 24 Construct streetcar1 0.00% - 0.00% 2,500,000$ 100.0% 49.8% 1,245,000$ -$ -$ 25 New rail route from Uptown to N Capitol Hill 0.00% - 0.00% 11,700,000$ 100.0% 49.8% 5,826,600$ -$ -$

Install bus shelters along bus routes in study area26 Install nine bus shelters 3.20% - 3.20% 235,000$ 55.6% 0.0% -$ -$

Transit Project Sub-total 14,875,000$ - - 7,336,404$ 1,516.00$ -$

Grand Total 71,215,000$ 1,486,000$ 3,478,000$ 14,875,000$ 22,925,979$ 2,080$ 1,555$ Cost per SF

Notes Unfunded Portion OnlyTotal project cost does not include negative costs (potential credits) where background traffic volumes have decreased between 2004 and 2030

Pro-Rata Share for Project

Total Costs from Mitigation Program Report (Tables 1-4)(Nov 05)Future

Developments Cost Share

Non-SLU Only Growth Adjustment (Mirai Table 5)(June

05) Adjusted Total Cost2030 Auto Based

ImpactsMode Conversion

Factor 2030 Impacts

C:\Heffron\Projects\Seattle\Denny Center\Excel\SLU Mitigation Spreadsheet Denny Centre - Outside SLU - 4-12-2016.xlsx <2030 Non-SLU Growth Cost Share> 4/12/2016

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