ITEM NO: ______7c_Supp 1_____ 
DATE OF MEETING: August 7, 2012













1

Purpose of Heffron Study 
Detail the Port's concerns to help the City, County and
Arena proponents evaluate the impacts and develop
mitigation measures 
Provide information about Port operations and how
those operations will change in the future 
Detail the types of analyses that should be included in
the arena's EIS 

heffron
t r a n s p o r t a t i o n , i n c . 
2

What we know and don't know 
The arena's transportation study was preliminary 
All admit that an EIS will be required 
The Port's marine terminals are affected by events in
the SoDo today 
A new arena will exacerbate that impact and add up to
100 weekday events per year 
No commitment for mitigation 

heffron
t r a n s p o r t a t i o n , i n c . 
3

What are the flaws of the arena study? 
Not an EIS 
No actual analysis of operations, safety, parking, transit or freight 
Incorrectly assumed that event traffic doesn't occur during
afternoon 
Incorrectly assumed that Port traffic does not move at night 
Incorrectly assumed that Port traffic stays west of 1st Avenue S 
Incorrectly assumed that Friday is not a weekday (or workday) 

heffron
t r a n s p o r t a t i o n , i n c . 
4

EIS versus Arena Study 
Key Arena   Safeco Field       CenturyLink   Arena Study 
EIS          EIS         Field EIS 
# Event Days                                              
Trip Generation                                            
Intersection                                   
Operations 
Arterial Operations                               
Safety Analysis                                  
Parking Analysis                                
Pedestrian Analysis                              
Alternative Sites        n/a                         

heffron
t r a n s p o r t a t i o n , i n c . 
5

EIS versus Arena Study 
# of Intersections Evaluated 
Key Arena EIS = 15 
Safeco Field EIS = 31 
CenturyLink Field EIS = 54 
Arena Study = 0 


heffron
t r a n s p o r t a t i o n , i n c . 
6

Port Concerns 
Additional events at a new arena will make it harder for
trucks to reach the Port, increase cargo shipping costs,
and affect the Port's ability to retain and attract customers 
Shippers primary criteria: 
Travel Time 
Reliability 

heffron
t r a n s p o r t a t i o n , i n c . 
7

Incompatible land 
uses will affect Port
operations 



heffron
t r a n s p o r t a t i o n , i n c . 
8

Events reduce the Port's effective operating hours 
Effect of Mariners Games on I-90 Traffic Entering SoDo 




heffron
t r a n s p o r t a t i o n , i n c . 
9

Events reduce the Port's effective operating hours 
Effect of Mariners Games on Terminal 46 Gate Moves 




heffron
t r a n s p o r t a t i o n , i n c . 
10

Port traffic will occur in the evenings and conflict with
new arena event traffic 
Effect of Night Gates on Hourly Traffic Volumes 
20%
Day Gate Only
18%                                   With Night Shift Gates

16%   Morning Commuter Peak Hour Trips
Reduced from 13% to 8% of Daily Traffic
Terminal Peak Hour Trips
14%                                Reduced from 14% to 9% of Daily Traffic
Percent of Daily Truck Trips  12%
Afternoon Commuter Peak Hour Trips
10%                                Reduced from 5% to less than 3% of Daily Traffic

8%

6%

4%

2%

0%
12:00 AM   1:00 AM   2:00 AM   3:00 AM   4:00 AM   5:00 AM   6:00 AM   7:00 AM   8:00 AM   9:00 AM   10:00 AM   11:00 AM   12:00 PM   1:00 PM   2:00 PM   3:00 PM   4:00 PM   5:00 PM   6:00 PM   7:00 PM   8:00 PM   9:00 PM   10:00 PM   11:00 PM
heffron
t r a n s p o r t a t i o n , i n c . 
11

Street vacations will
exacerbate congestion
along the Port's main
freeway access routes 
I-90 & I-5 
T-46 

T-5, 18 & 30 
S Massachusetts St 

heffron
t r a n s p o r t a t i o n , i n c . 
12

Additional pedestrian and vehicular activity on Holgate
Street will increase the risk for train-related collisions and
rail and road system delays 




heffron
t r a n s p o r t a t i o n , i n c . 
13

Holgate Street Crossing After Event 





heffron
t r a n s p o r t a t i o n , i n c . 
14

Concurrent events greatly exacerbate congestion 
to, from, and within SoDo 
Findings from King County Expert Review Panel 




heffron
t r a n s p o r t a t i o n , i n c . 
15

Concurrent events greatly exacerbate congestion 
to, from, and within SoDo 
Findings from King County Expert Review Panel 
Weekday Events    Weekend Events 
Base    Banner   Base    Banner
Year     Year     Year     Year 
Safeco & CenturyLink Field     65      79      46      51 
# of Concurrent Events        1       1       5       5 
New Arena              71     101     33      41 
Grand Total              136     180      79      92 
# of Concurrent Events        7      23      10      17 

heffron
t r a n s p o r t a t i o n , i n c . 
16

Alternative sites have not been considered 
Ten alternative sites were evaluated for Safeco Field 
Five sites in vicinity of Kingdome 
Myers Way near Olson Place 
Seattle Commons 
South Lake Union 
Bus Barn Site at 5th & Mercer 
Sand Point at Magnuson Park 


heffron
t r a n s p o r t a t i o n , i n c . 
17

Arena has not detailed its mitigation needs 
or identified funding for mitigation 
Additional Parking 
Pedestrian Improvements 
Public Benefits for Street Vacations 
Police-officer control 
Street system improvements 
Traffic management 
Trip reduction plan 

heffron
t r a n s p o r t a t i o n , i n c . 
18

What needs to be done? 
An EIS must be performed for arena 
Evaluate alternative sites 
Identify mitigation measures that retains Port operations 
Work with the Port on event traffic controls 
Commit to mitigation with funding and implementation strategy 


heffron
t r a n s p o r t a t i o n , i n c . 
19