Mount Baker Ridge Tunnel
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Mount Baker Ridge Tunnel Mount Baker Tunnel
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 East portals of the two older tunnels
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| use | Motorway , bike path , footpath | |||
| traffic connection |
Interstate 
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| place | Seattle | |||
| length | 440 m tunnel + 600 m roofing | |||
| Number of tubes | 3 | |||
| Largest coverage | 38 m | |||
| construction | ||||
| start of building | 1939 (first two tubes)
1983 (third tube) |
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| business | ||||
| operator | Washington State Department of Transportation | |||
| release | 1940 (first two tubes)
1986 (third tube) |
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| location | ||||
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| Coordinates | ||||
| East portal | 47 ° 35 ′ 24 ″ N , 122 ° 17 ′ 19 ″ W. | |||
| West portal | 47 ° 35 ′ 24 ″ N , 122 ° 18 ′ 9 ″ W. | |||
Map with all coordinates: 
The Mount Baker Tunnel or Mount Baker Tunnel are located in the US state of Washington and lead the Interstate 90 under the Mount Baker Neighborhood of Seattle through. The facility consists of three tunnels : the first two were opened in 1940 together with the Lake Washington Floating Bridge , the third in 1991. The tunnels lead under eight lanes of the freeway, as well as a pedestrian and cycle path, which is in the third tunnel above the lanes of the interstate to be led.
The tunnels were added to the National Register of Historic Places (# 82004243) in 1982. The American Society of Civil Engineers (ASCE) recognized the construction project with the Outstanding Civil Engineering Achievement Award in 1990 and has listed the east portals together with the Lake Washington Floating Bridge as a Historic Civil Engineering Landmark since 2008 . Furthermore, the tunnels are a Seattle landmark .
history
The first two tubes
In the early 20th century, ways were sought to better develop the east coast of Lake Washington from Seattle. With government funds made available during the Great Depression , the Lake Washington Bridge Project was implemented, which leads US Highway 10 from Bellevue via Mercer Island to Seattle. The project includes not only the heart of the Lake Washington Floating Bridge , the East Channel Bridge which traffic from Bellevue brings Mercer Iceland and the tunnel through Mount Baker, which the traffic of the floating bridge brings to the city of Seattle. Originally only one tube was planned, the project was later extended to two lanes and one sidewalk per tunnel.
The construction of the tunnel was in 1939 for 1.37 million US dollars to the Bates and Rogers Construction Company awarded. The construction work on the east portal began with a 115-day delay due to disputes over the right of way - it was planned to drive the entire tunnel from the east. When it was determined that the planned opening date could not be met, the construction loan was increased by 30,000 US dollars so that digging could also be carried out from the west side. The breakout in the blue shade in the Belgian construction method took place without explosives and drilling only through the dismantling with a pneumatic hammer , whereby a very strong expansion was necessary to stabilize the plastic material. The core was with an electric excavator degraded the material to an electric Lorenbahn were loaded. The tunnel construction was accompanied by great difficulties. Settlements of up to 30 cm led to mountain damage on the streets and houses above. The construction of both portals triggered major landslides . Nevertheless, it was possible to open the tunnel together with the Lake Washington Bridge on time on July 2, 1940.
With the increasing traffic in the sixties, the two inner lanes were equipped with variable message signs so that they could lead westwards or eastwards depending on the main traffic direction.
The third tunnel tube
In 1986, as part of the expansion of US Highway 10 to Interstate 90, the two existing tubes were supplemented by a third tube with a significantly larger diameter. A unique method of construction was awarded to Guy F Atkinson Construction Co for $ 38.3 million . First, an excavation pit 27 m deep and 30 m in diameter was created in front of the future tunnel portals. From here, the tunnel walls were constructed by executing 24 circular adjoining drives with a diameter of 3 m and each drive being pressed with concrete immediately after completion. Then the excavation was carried out starting from the dome , protecting the already finished lining . The interior fittings for the three traffic levels were carried out with prefabricated beams and panels.
All three tunnels were extended west of Mount Baker Ridge by a covering of 600 m for the purpose of noise protection. The roofing was the result of an objection from residents who delayed the construction of Interstate 90 since the 1970s. The Mount Baker Tunnels are part of the last seven mile stretch of Interstate 90, which was completed in 1992.
After the opening of the third tunnel tube, the two existing tubes were renovated in 1993.
Building
Tunnel tubes from 1940
The first two tubes are laid at a center distance of 18.2 m and have a horseshoe-shaped cross-section with a width of 8.8 m, the overlap measures 38 m at the thickest point. When they were completed, the tunnels had the largest cross-section excavated in loose rock . Each of the two tubes is ventilated with three air ducts, which lead to a common ventilation shaft above the tunnels.
The Art Deco tunnel portals on the east side were designed by the architect Lloyd Lovegren. The artist James Fitzgerald designed the three bas-relief panels originally embedded in them with motifs of the Northwest coast Indians . The center plate bore the inscription City of Seattle Portal of the North Pacific , the other the inscriptions The Orient and Alaska . At night the portal was illuminated with spotlights . When the third tube was opened, two of the three plates were removed - with the new traffic regulations, drivers would only have been able to see them in the rearview mirror anyway.
Originally, each tube had two 3.7 m wide lanes and a 90 cm wide sidewalk, with the south tube being used by traffic moving eastwards, while traffic in the north tube was flowing west. With the opening of the third tunnel tube, the two existing tubes will only be used by traffic to the east, with one lane with a hard shoulder in the south tube and two lanes without hard shoulder in the north tube.
Tunnel tube from 1986
The third tube, opened in 1986, with an inner diameter of 19.4 m, was again the tunnel with the largest diameter in loose rock when it was completed. The three levels for the traffic routes are suspended in the shell with concrete beams and plates. The lowest level is used by two lanes, which, depending on the main traffic direction, lead to the west or east and are withheld from public transport and car pools. The three westward lanes use the middle level and at the top is the pedestrian and cycle path. The inscription Seattle - Portal to the Pacific was placed above the portal of the middle level, similar to the old tubes .
Web links
- ASCE History and Heritage International Landmark Nomination for: Lacey V. Murrow Memorial Bridge and Mount Baker Ridge Tunnels. (PDF; 4.3 MB) ASCE Seattle Section, accessed November 24, 2013 .
Individual evidence
- ^ Washington - King County. NHRP, accessed November 23, 2013 .
- ^ Lacey V. Murrow Bridge and Mount Baker Ridge Tunnels. (No longer available online.) ASCE Site, archived from the original on October 31, 2013 ; accessed on November 16, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Seattle Landmarks: Lacey V. Murrow Floating Bridge and East Portals of the Mount Baker Tunnels (1940). HistoryLink.org, April 23, 2001, accessed November 23, 2013 .
- ↑ a b c d e Mount Baker Ridge Tunnel. (PDF; 146 kB) (No longer available online.) In: Historic American Engineering Record. Formerly in the original ; accessed on November 24, 2013 . ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ^ Robert A. Robinson, Edward Cox, Martin Dirks: Tunneling in Seattle - A History of Innovation. Discovery, accessed November 24, 2013 .
- ^ Robert A. Robinson, Harvey W. Parker: Seattle renews its large diameter legacy . In: North American Tunneling Journal . ( news.hntb.com [PDF; accessed November 24, 2013]). news.hntb.com ( Memento of the original from April 2, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ David Wilma: Residents file suit to stop Interstate 90 project on May 28, 1970. HistoryLink.org, April 8, 2008, accessed November 24, 2013 .
- ↑ MK Hurd: Seattle Lid covers I-90. (PDF; 122 kB) (No longer available online.) The Aberdeen Group, 1990, archived from the original on February 22, 2014 ; accessed on November 24, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
