0

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Study Methods and Assumptions • Analysis conditions and study area

• Demand forecasts and projects

• Performance measures

• LOS standards

DRAFT ANALYSIS FOR',EEVI

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Conditions and Study Years ,

Conditions Year

- - - . -- - -I I:

If Existing1 No~B.µild1 I Constrµc_t i9rtl Ultimate I - . ' - -

2016 x 2020 x x 2035 x x

• Existing & No-Build Conditions

• Ultimate Condition - Assumes both 1-90 Two-Way Transit and HOV and East

Link projects are built and operating

- Option 1: Ml vehicles able to use HOV lanes and ICW

- Option 2: Ml vehicles restricted from HOV lanes and ICW

DRAFT AN!\LYSIS FOR RE'i

Conditions and Study Years

• East Link Construction - Mid-point of construction (2020)

- 1-90 Two-Way Transit and HOV Project completed

- Operational Scenarios: • Ml SOV eligible to use the HOV lanes and ICW

• Ml SOV restricted from the HOV lanes and ICW

• HOV lane converted to a general-purpose lane

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Study Area

\ ¥ \ 1 ~ J' . \ \

.......... ~- .9 .. . • 1 :s .. _ .. -~---~

• 1-90 from 1-5 to 1-405 • Analysis conducted for both AM and PM peaks • Study area includes freeway and lo.c~at S;tu.eets

DRAFT ANALYSIS iFFOR REVI

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·o o o Future Forecasts and Projects

• PSRC model - Forecasts for 2020 and 2035

- Utilize PSRC adopted Land Use Targets forecast

• Sound Transit model - Bus and light rail ridership forecasts

• Reasonably foreseeable projects: - Includes Connecting Washington projects

- 1-90 Two-Way Transit is completed immediately prior to East Link construction

- ST 2 program is complete by 2035

- ST 3 is not assumed

DRAFJi ANALYSIS F.OR RE~

Performance Measures and Standards

• Performance Measures - Vehicle and transit demand forecasts

- Intersection LOS and vehicle queues

- Vehicle travel times

• Agency LOS Standards -WSDOT LOSE

- Mercer Island (town center) LOS C

- Mercer Island (outside town center) LOS D

• VISSIM and Synchro used for analysis results

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Draft Analysis Results

• Existing Conditions/Field Verification

• Future Traffic Forecasts and Travel Patterns

• Intersection LOS

• Travel Times on Mercer Island

• 1-90 Ramp Operations

Existing Conditions Intersection LOS ~

20161Exlstfn1 ,tandltlons -

l LOS lhtersection1

ID lnter5eCtton• - I 1stanifan11

201 W Mercer Way/1-90 Ramp E 202 W Mercer Way/SE 24th Street D A B

203 76th Avenue SE/N Mercer Way/1-90 Westbound on-ramp E A c 204 76th Avenue SE/SE 24th Street c A B

205 77th Avenue SE/N Mercer Way c 0 E 206 77th Avenue SE/1-90 Westbound express lanes ramp E A B

207 77th Avenue SE/1-90 Eastbound Off-Ramp E B B

208 77th Avenue SE/Sunset Highway SE c B c 209 77th Avenue SE/SE 27th Street c B B

210 80th Avenue SE/N Mercer Way c c c 211 80th Avenue SE/1-90 WB/EB HOV Direct access E A B

213 80th Avenue SE/SE 27th Street c B c 214 81st Avenue SE/North Mercer Way D c B

215 Island Crest Way/N Mercer Way/1-90 Westbound off-ramp E B c 216 Island Crest Way/1-90 Eastbound On-Ramp E c c 217 80th Avenue/SE 28th Street c A 8

218 Island Crest Way/SE 28th Street c c c 220 Island Crest Way/SE 40th Street D c D

221 78th Avenue/SE 40th Street D A c 222 East Mercer Way/1-90 Westbound ramp E B c 223 East Mercer Way/1-90 Eastbound off- ramp E 8 A

224 East Mercer Way/1-90 Eastbound on-ramp/SE 36

Notes: 1

- LOS Standards by agency are: Mercer Island - LOS D (LOS "C"for Town Center Arterial Intersections), WSDOT- LOSE

DRAFJ" AN~LYSIS frGF.l· F.tE\llEW

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Existing Conditions Travel Times llDl•s..19 - ) ~ROA~OK; ' I"- \ t I

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Route 38 T 76th Avenue . , ... SE (via N Mercer Way)

ft • IC

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MERCEJ ;,~\VIII ICJWn l..t!nlll!f'I I r· 1 o~~ I Travel Time Route

ISi.AND 1'41.1

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r : ' !Ci I 1 - W Mercer Way

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l ;:I J 3A- 76'h Avenue SE

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-- (via Town Center)

!- It i . .,,, ..

f f .. i 38 - 76th Avenue SE

Route 1 • W Mercer way •x ti h ~ trl . i · U.TI:>S.

""-.- __ _ I ii t ' ... (via N Mercer Way) " .. r

AM Peak Travel lime (minutes)

I 7

5

' --

7 ----- -

7

Travel Pattern Field Verification

• Conducted origin-destination counts on N. Mercer Way in AM - Up to 60 vehicles/hour use Island Crest Way WB off­

ramp to 77th WB center roadway on-ramp

• Average vehicle occupancy (AVO) count on 1-90 and Island Crest Way ramp - 16°/o HOV share in the WB direction in AM

• Ramp utilization in PM period

D~AFT ANAl.L YSIS iF0H IREV..1

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·o o o 1-90 and Mercer Island Traffic F'orecasts

1-90 across Lake Washington

AM Peak Hour

PM Peak Hour

.Existing 201.6.

11,800 vehicles

13, 100 vehicles

Future 2035

12,900 vehicles

14,400 vehicles

Percent Growth

9%

10%

Mercer. 11sland L Existing 2016 _JL_ Fu~~re 2035 _!l Percent -

HOV 0;0

I Growth , ~

Total Volume HOV 0/o Total Volume - _J '

AM To Mercer Island 2,500 13% 2,750 13% 10% Peak Hour From Mercer Island 3,300 14%

; 3,700 14% 12% i

-

PM To Mercer Island 3,400 17% 3,850 17% 13% Peak Hour From Mercer Island 3,250 19% 3,550 I 19% 9%

Source: PSRC model

DRAF.T ANALYSIS FOR REVI

Mercer Island AM WB 2035 Travel Patterns

0

- -·----- -- -~- "-. ·~

Nat· to Sc=* ·761hA~SE on-«amp

:ll t'I ~ t W Mercer Way

51 ~ . on-Ramp

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Build Opt 1 Westbound On-Ramp Volume

Build Opt 2 Westbound On-Ramp Volume

11 :+ : jl Build Opt 2 Volume Is Greater than Build Opt 1

Build opt 2 Volume Is Less than Build Opt 1

Build Opt 2 Volume Is Equal to Build Opt 1

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DRAIT ANAILYiSIS .FOR i~EVIE

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Mercer Island PM EB 2035 Travel Patterns - .---..----..---

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Off-Ramp

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Off-Ramp

~ ~80 17-

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~ Bulld Opt 1 westbound on-Ramp Vobne

hiidil Buld Opt 2 Westbound Oft-Ramp Vobne -~

Bulld Opt 2VolumeIsGreaterthanBulldOpt1

BuUd Opt-2 Volume Is Less than Bulld Opt 1

Bulld Opt 2 Volume is Equal to Build Opt 1

Island crest Way Off-Ramp (HOV)

-·llllO ~ I 630 ·---""" I 210

-420

r· <Mlwr IC:~

Island Oest Way M - ..

a: <;:: * Offf-~Ramp fOUt~:)

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DRAFT ANALYSIS ·FOF.:UREVI

1,

r

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l \ E Mera!rWay ~ Off-Ramp

N

"~ - ~·211 .-...,. . i'

~ 1 ~

, ..._ lllW-< I ~ ~~35 ~I' I 135 ~' ~-·~ \

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Initial Future 2035 AM Results 76"' Avenue SEIN Mercer Way/ 1.90J B "li:lla r 1' L Bulld"Optlon 2 JL Build Optlolli2

Westbound On-ramp ur - · ·- P ion J ! (unmitigated) (mitigated) -- - - __, --- -

Intersection LOS LOSB LOSE

AM Westbound approach LOS LOSC LOS F Peak Hour Westbound Queue Length1 425 feet >1/2 mile

Travel Time2 4 mins >10 mins Notes: 1 - Queue storage length is 750 feet to adjacent intersection at 771h Ave SEIN Mercer Way 2 - Travel time route begins at Island Crest Way/SE 28th Street and ends at W Mercer Way on-ramp gore

Notto Scale

Route - Via N Mercer Way

~

f SE74UI "t

i ~ ~ ~ XI

From: Island Crest Wav/SE 28th Street To: Westbound 1-90 via 76th Avenue SE On·ramp

~ ;f !l ~ > > ;; '

DRAFT ANALYSIS frOR F.lEV:IE

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• Mercet lshlt!d Ct>mmiiiiity & E

BEAUMONT

LOSS

LOSB

425 feet

4 mins

0

· o o o 761h WB On-Ramp Modification

• Modified 76th WB on-ramp and ramp terminal to: - Based on 2035 analysis, modify transit-only bypass to

a metered shoulder when storage is needed (similar to Island Crest Way eastbound on-ramp).

- Adjusted ramp metering rate to accommodate on­ramp demand

- Signalize 76th/North Mercer Way ramp terminal

0

Year 2035 Intersection LOS 2035 Future Conditions

Intersection I ID lnlersectJon

AMPHkttour PM Peek ttour LOS

standanf" :1 BulJd 201 llW Mercer Way/1-90 Ramp I E I B I 8 II B I C

2

202 W Mercer Way/ SE 24th Street D A B B B ,

1 203 76th Avenue SE/ N Mercer Way/1-90 Westbound on-ramp E B B C C '

I 204 76th Avenue SE/ SE 24th Street C 8 B B 8 • • 205 nth Avenue SE/ N Mercer Way c B B A A I

206 lnth Avenue SE/HID Westbound express lanes ramp I E

207 lnth Avenue SE/1·90 Eastbound Off·Ramp I E

208 I 77th Avenue SE/ Sunset Highway SE I C

209 I nth Avenue SE/ SE 27th Street I C 210 l80th Avenue SE/ N Mercer Way I C 211 l80th Avenue SE/ 1-90 WB/ EB t!OV Dlrea access I E

212 l80th Avenue SE/1-90 EB HOV Oirea access I E

213 l80th Avenue SE/ SE 27th Street I C -

214 81st Avenue SE/ North Mercer Way 0 215 Island Crest Way/ N Mercer Way/ 1·90 Westbound off-ramp E

216 II Island Crest Way/1·90 Eastbound On-Ramp I E

217 IBOth Avenue/ SE 28th Street I C

218 I ls land Crest Way/ SE 28th Street I C

219 I Island Crest Way/ SE 30th Street I C

220 I Island Crest Way/ SE 40th Street I D

221 l78th Avenue/SE 40th Street I D

222 I East Mercer Way/1-90 Westbound ramp I E

223 I East Mercer Way/1-90 Eastbound off-ramp t E

224 !East Mercer Wav/1-90 Eastbo~nd on-ramp/SE 36th Street I E

Notes:

B B

B

c B A

c c c c B

c N/A

c A 8

B

6

B I B I B

B ll C I C

6 I B I B c ,, c l c B I 8 I B A I A I A c I c - 11 - c

c I c I c c c c c I c I c B I B I B c I c I c

N/A I N/A I N/A C I D I D A I B I B 8 ~c I c

: I : I : I 1

• LOS Standards by agency are: Mercer Island - LOS D (LOS "C" for Town Center Arterial Intersections ), WSDOT • LOS E LOS resutts include all East Li nk Fina l EIS mit igation and 76th Avenue ramp mod if ications.

DRAFT ANALYSIS lr'OR REV·IE

0 0

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Year 2035 AM Travel Times

---

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~-­'*-•

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Rout~ l • W Mam Way 111;. ~-

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DRAFr ANALYSIS FOR !REV

Travel Time II AM Peak Travel llme (mlns)

Route Ill Build Opt 1 Build Opt 2

1 - W Mercer Way 7 7

2 - Island Crest Way 4 3

3a - 761h Avenue SE 7 9 (via Town Center)

3b - 761h Avenue SE 7 9 (via N Mercer Way)

Average Travel Time 6.0 7.5 {weighted by traffic volume)

Potential Intersection Mitigation

West Mercer Way & 24th Mercer Island Final EIS Southbound left-turn Avenue SE

80th Avenue SE & SE 27th Mercer Island Final EIS Install traffic signal Street

77th Avenue SE & North Mercer Island Final EIS Install traffic signal Mercer Way

77th Avenue SE & 1-90 WSDOT Final EIS Install traffic signal eastbound off-ramp

North Mercer Way & 76th WSDOT Final EIS/ Final EIS - Modify westbound westbound on-ramp Updated Analysis channelization

Updated analysis - install traffic signal and modify ramp

76th westbound on-ramp WSDOT Updated Analysis Re-stripe transit only bypass to metered shoulder when needed

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