Seattle Tube proposes a twin tunnel under 6th Avenue with a new expressway to link with I-90 and the West Seattle Freeway. Cascadia proposes a single bore tunnel under 1st with an alignment to the existing 99 route. We believe either deep bore tunnel approach is better for Seattle than what is currently on the table. Come share your ideas and concerns.

It is your city. This is a unique situation where concerned citizens can triumph over special interests and half-hearted government efforts to solve a complex problem.

The Deep Bored Tunnel will:

Remove through town traffic completely from the surface streets of the waterfront and downtown areas allowing:

- for the creation of a meaningful connection from the city to the waterfront
- The redevelopment of the waterfront to a world class level befitting the city

The Deep Bore Tunnel technology is an increasingly known methodology with predictable schedule and budget outcomes:

- The Cascadia center sponsored dialog with the state has opened the way to understanding that the projected costs for this approach are considerably less than previously thought.

The Deep Bore option holds the possibility to allow the existing Viaduct to remain in operation for longer while major components of the new solution are being constructed.

The Seattle Tube proposal embraces all of these advantages AND…

· Parses through-town traffic stream from the Downtown destined traffic at the Duwamish crossing, relieving congestion as commuters approach downtown and facilitating traffic flow overall
· Adds the SODO EXPRESSWAY with the opportunity to strategically link this route to I5 and I90
· With its uptown route entirely under the 6th ave right of way avoids such challenges as the
o 3rd ave metro tunnel
o The 4th ave railroad tunnel
o The city of seattle sewer main running through downtown

Thank you in advance and we look forward to seeing you soon

David Petrich - Puget Sound Magazine
Ralph Allen - Grace Architects

GRACE ARCHITECTS
1927 post alley seattle 98101
Dir. Office Ph. 206.788.4604
Office Ph. 206.957.9800
Fax 206.682.3159
Cell Ph. 206.399.9467
Email rwallen@gracearchitectspllc.com

Industry leaders in Ballard are concerned about eliminating the Alaskan Way Viaduct because it will make freight and fuel deliveries more difficult. Many who are responsible for getting cargo in and out of the Ballard area prefer an elevated expressway replacement. However, easy access to I-90 has always been a problem for eastbound truckers coming off the viaduct from Ballard since ball games and railroad crossings often impede passage between the two routes.

Seattle Tube proponents are hoping to convince ballard businesses about the possibility of building a more efficient transportation route by going under the city rather than along the waterfront. The below 6th Avenue route proposed by Seattle Tube supporters features a smooth even grade that won’t bog down heavy trucks. The new SoDo Expressway, also included in the Seattle Tube corridor plan, will carry non-stop traffic down towards the Georgetown area where it will connect with first avenue at Diagonal Street with an exit to the West Seattle Freeway.

Citizens for Seattle Tube are requesting that SDOT consider allowing integration of the West Seattle Bridge 4th Avenue exit ramps with the proposed SoDo Expressway. The SoDo Express way, straddled over 6th Avenue South, is promised to give West Seattle rapid access to the north side of the city as well as a less congested route to reach I-90.

Seattle Tube anticipates that SDOT will welcome the idea since it will reduce congestion at the I-5 interchange which is currently one of two major bottlenecks for West Seattle in the morning commute. The proposed eastbound SoDo “fly over” ramp will also lighten up the traffic load on the other morning bottle neck where trucks and buses presently slow to a crawl to negotiate the tight turn onto the old northbound 99 route.

In a meeting yesterday with Councilman Tom Rasmussen and Cascadia Director Bruce Agnew, who viewed the Seattle Tube traffic plan, words of encouragement were offered as they both agreed the proposal should be looked at very closely by both SDOT and WSDOT since it could solve a number of traffic problems plaguing the city. The proposed plan included a bored tunnel under downtown as a new alternative to the Alaska Way Viaduct replacement project.

Above is the proposed West Seattle - SoDo Expressway interchange. Bellow is the current SDOT plan.

Source: Seattle Department of Transportation South Spokane Street Project

Citizens for Seattle Tube, a rapidly growing contingency of Seattle area commuters and business owners, is thankful that the Governor has sensed the need to study the Alaskan Way Viaduct replacement project a little further. The two options put forth by WSDOT, a new waterfront viaduct versus a labyrinth of surface street modifications, just isn’t solving all the issues for Seattle. Despite pressure to make a final decision, the governor is doing what good leaders do–she is making sure that all options are considered.

The Governor has heard hints of a new tunnel possibility that some claim have not been thoroughly evaluated by WSDOT. New technologies have emerged in recent years show that tube-style bored tunnels have proven out to be the best fix for difficult traffic problems like Seattle has. The governor is looking into seeing if the problem can be solved in “3D” while most are still thinking in “2D” according to Bruce Agnew of Cascadia, a regional transportation adviser.

When many hear the word “tunnel” they are thinking of the waterfront cut and cover tunnel turned down by voters in the 2007 Measure 2 public advisory poll. It has been difficult for WSDOT to pursue other tunnel options because of the negative stigma generated by the waterfront tunneling folly. Special interest groups have been highly vocal and influential in garnishing waves of public discord at every turn, frustrating traffic engineers and tainting the possibilities for clear resolutions. The controversy over what to do about the Alaskan Way Viaduct Replacement project has gone on so long that the situation has gotten toxic.

While the Governor has been adamant about bringing the viaduct situation to a head with the firm position that “buck stops here”, she has made it clear that she is not going to condemn Seattle and the State of Washington with results of a marginally supported decision.

There is no doubt that tunnel fires can be very hazardous. One of the worst tunnel accidents occurred in France in 1999 as reported by an article published by The Independent where 35 people lost their lives in a 40 vehicle pile-up. The vintage 1960’s era single bore tunnel was lacking modern fire suppression, escape routes and adequate ventilation according to investigators. Much has been learned since then says experts.

A number of recent patents filed for tunnel fire suppression systems is evidence that tunnel builders have made extensive progress in making tunnels safe for trucks, busses and cars. One such technology uses a breathable gas to dowse flames, allowing fires to be quickly extinguished in enclosed tunnel environments. Extensive work has been done to retrofit tunnels in Japan and Europe with automatic water spray and mists systems which reportedly cool the air quickly around a fire to minimize the effect of hot gasses.

It is not clear yet what fire suppression technologies will be used in a bored tunnel option under downtown, but it is apparent that engineers have a wide range of options to consider. Citizens for Seattle Tube is pressing engineers to come up with a way to allow safe passage of freight through the 2.2 mile long twin bore tunnel it proposes under 6th avenue connecting South Lake Union with the Sodo District.

A few interesting resources:

Challenges for use of fixed fire suppression systems in road tunnel fire protection

Comparison of Fixed Fire Fighting System Effectiveness in Road Tunnels-
High-Pressure Mist vs. Standard Sprinkler

Numerical Simulation of Water Mist Suppression of Tunnel Fire Scenarios

Latest Tunnel Design Concepts For Complete Fire Safety [Download PPT File]