Yerba Buena Tunnel

Preliminary surveys to lay out the route of the planned Bay Bridge were held in April 1931.{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=HT19310428.2.7 |title = Trans-Bay Bridge Nearing Reality |date = April 28, 1931 |newspaper = Healdsburg Tribune |access-date = December 20, 2017 }} Dedication ceremonies were held on February 24, 1932,{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1932_feb.pdf |title = Impressive Ceremonies Mark Official Start of Work on Transbay Bridge |date = February 1932 |magazine = California Highways and Public Works |volume = 10 |issue = 2 |pages = 22–23, 39 |publisher = California Department of Public Works |access-date = December 20, 2017 }} and by April 1932, the final design for the Bay Bridge, including the single-bore tunnel through Yerba Buena Island, had been completed and submitted for approval.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1932_apr.pdf |title = General Final Plan Accepted for the San Francisco-Oakland Bay Bridge |date = April 1932 |magazine = California Highways and Public Works |volume = 10 |issue = 4 |pages = 22–23, 42 |publisher = California Department of Public Works |access-date = December 20, 2017 }} The contract to build the Yerba Buena Cable Anchorage, Tunnel & Viaduct segment was opened for bids on March 28, 1933, and awarded to the low bidder, Clinton Construction Company of California, for $1,821,129.50 (equivalent to ${{formatprice|{{inflation|US-GDP|1821129.50|1933}}}} in {{inflation-year|US-GDP}}{{inflation-fn|US-GDP}}).{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1933_apr.pdf |title = Savings of Over $9,000,000 Shown in San Francisco—Oakland Bridge Bids |date = April 1933 |magazine = California Highways and Public Works |volume = 11 |issue = 4 |pages = 4, 15 |publisher = California Department of Public Works |access-date = December 20, 2017 }} Yerba Buena Island was the main site of the official groundbreaking for the Bay Bridge on July 9, 1933, when President Franklin D. Roosevelt remotely set off a dynamite blast on the eastern side of the island at 12:58 p.m. local time.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1933_dec.pdf |title = Huge Monolith Rises from Bay Waters to Bear Bridge Tower |date = December 1933 |magazine = California Highways and Public Works |volume = 11 |issue = 12 |pages = 14–15 |publisher = California Department of Public Works |access-date = December 20, 2017 }} Former President Herbert Hoover and Governor James Rolph were onsite; the two men were the first to turn over the earth with ceremonial golden spades.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1933_julaug.pdf |title = Governor Rolph, Breaking Ground for Bay Bridge, Puts Hundreds to Work |last = Purcell |first = C.H. |date = July–August 1933 |magazine = California Highways and Public Works |volume = 11 |issue = 7–8 |pages = 2–3;12–13;26 |publisher = California Department of Public Works |access-date = December 20, 2017 }} Other ceremonies took place simultaneously in San Francisco (on Rincon Hill) and Oakland Harbor.{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=HTES19330713.2.11 |title = Three fetes mark start of Bay Bridge |date = July 13, 1933 |newspaper = Healdsburg Tribune, Enterprise and Scimitar |access-date = December 20, 2017 }}{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1933_may.pdf |title = President Expected to Assist in Bay Bridge Ceremony |date = May 1933 |magazine = California Highways and Public Works |volume = 11 |issue = 5 |pages = 6 |publisher = California Department of Public Works |access-date = December 20, 2017 }}

The Yerba Buena Tunnel opened, along with the rest of the Bay Bridge, on November 12, 1936. {{As of|2019|post=,}} the tunnel lacks an official name.{{cite report |url = https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/place-names/web-2019-named-freeways-final-a11y.pdf |title = 2019 Named Freeways, Highways, Structures and Other Appurtenances in California |author = |date = 2020 |publisher = California Department of Transportation |access-date = May 31, 2021 }}

On January 30, 2016, a chunk of concrete the size of an automobile tire fell from the tunnel wall into the slow lane of eastbound traffic on the lower deck of the Yerba Buena Tunnel, causing a minor accident. The concrete fell from where the upper deck is connected to the tunnel wall. Based on an examination of photographs, a professor from Georgia Tech postulated that water infiltration into the concrete wall had caused the reinforcing steel to corrode and expand, forcing a chunk of the tunnel wall out.{{cite news |url = http://www.sfgate.com/bayarea/article/New-Bay-Bridge-corrosion-probe-Concrete-chunk-6812704.php |title = New Bay Bridge corrosion probe: Concrete chunk falls in tunnel |last = Van Derbeken |first = Jaxon |date = February 6, 2016 |newspaper = San Francisco Chronicle |access-date = December 21, 2017 }} A subsequent California Department of Transportation (Caltrans) investigation identified 12 spots on both sides of the tunnel wall in the lower deck space showed signs of corrosion-induced damage, but no immediate risk of further spalling. The apparent cause was rainwater leaking from upper deck drains. Caltrans engineers speculated the Masonite pads had swelled due to rainwater infiltration, cracking the tunnel walls and allowing moisture in to the reinforcing steel.{{cite news |url = http://www.sfgate.com/bayarea/article/More-damage-found-to-concrete-wall-in-Bay-Bridge-6845771.php |title = More damage found to concrete wall in Bay Bridge tunnel |last = Van Derbeken |first = Jaxon |date = February 21, 2016 |newspaper = San Francisco Chronicle |access-date = December 21, 2017 }}

Repairs to the degraded concrete started in February 2017. Drains and catch basins were replaced to reduce the likelihood of clogging, and fiberglass-reinforced mortar was used to patch removed concrete. The repairs, which required some daytime lane closures, were expected to last until June 2017.{{cite news |url = http://www.sfgate.com/bayarea/article/Daytime-lane-closures-for-Bay-Bridge-tunnel-11012912.php |title = Daytime lane closures for Bay Bridge tunnel repairs |last = Cabanatuan |first = Michael |date = March 19, 2017 |newspaper = San Francisco Chronicle |access-date = December 21, 2017 }}

California Department of Transportation engineer C.H. Purcell served as chief engineer for the Bay Bridge, including the construction of the Yerba Buena Tunnel. Before starting excavation, the ground through which the western half of the tunnel would be bored was stabilized by injecting cement grout under pressure through 25 {{convert|1.5|in|adj=on}} holes bored into the loose rock over the crown of the tunnel.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1935_sep.pdf |title = Safety Method of Boring Yerba Buena Tunnel Leaves Core to be Removed |date = September 1935 |magazine = California Highways and Public Works |volume = 13 |issue = 9 |pages = 20–21 |publisher = California Department of Public Works |access-date = December 20, 2017 }}

After excavating the western and eastern open portals, three drifts were bored from west to east along the path of the tunnel: one at the crown and the other two at the lower corners. The first drift broke through in July 1934, approximately one year after the start of construction.{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=MT19340623.2.56 |title = Yerba Buena Tunnel Diggers Near Light |date = June 23, 1934 |newspaper = Madera Tribune |access-date = December 20, 2017 }} A ceremonial party led by Governor Merriam celebrated the completion of the first {{convert|12|ft|m|adj=mid|-square}} drift on July 24 by walking through it, followed by a short speech.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1934_aug.pdf |title = Governor Merriam Leads First Party Through Yerba Buena Pioneer Bore |date = August 1934 |magazine = California Highways and Public Works |volume = 12 |issue = 8 |pages = 16–17 |publisher = California Department of Public Works |access-date = December 20, 2017 }}{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=HT19340725.2.8 |title = Island shaft for Bay span is completed |agency = United Press |date = July 25, 1934 |newspaper = Healdsburg Tribune |access-date = December 21, 2017 }} The space between the three drifts was then excavated, resulting in a single arch-shaped bore (in cross-section), and the tunnel roof was constructed using {{convert|16|in|adj=on}} steel I-beam ribs spaced {{convert|3|ft}} apart to support the rock, which were then embedded in concrete up to {{convert|3|ft}} thick at the crown. No cave-ins occurred during the excavation of the tunnel.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1937_feb.pdf |title = Construction History of San Francisco Bay Bridge |last = Andrew |first = Charles E. |date = February 1937 |magazine = California Highways and Public Works |volume = 15 |issue = 2 |pages = 10–11, 20 |publisher = California Department of Public Works |access-date = December 20, 2017 }}

After the roof was completed, the remaining core of rock between the tunnel roof and lower deck was excavated using a power shovel. By May 1935, work on removing the core was progressing and 40 steel ribs had been placed; concrete embedment was just starting.{{cite magazine |url=http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1935_may.pdf |title=Bay Bridge to Have 16 Toll Stations All Located on the Oakland Approach |date=May 1935 |magazine=California Highways and Public Works |volume=13 |issue=5 |pages=12–13 |publisher=California Department of Public Works |access-date=December 20, 2017 |quote=Far inside Yerba Buena, miners have bored ribs down from a crown tunnel to two side tunnels and placed 40 I-beams in these lateral drifts. For {{convert|20|ft|m|disp=sqbr}}, steel lining has been placed on top of the I-beam ribs, and the space between these plates and the rock roof has been packed with broken rock. The work of concreteing this loose rock above the steel, all of which later will be encased in concrete, has just been started.}} Removal of the core was completed on November 18, 1935.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1936_nov.pdf |title = Chief Engineer Purcell Tells Construction Story of the Bridge |last = Purcell |first = C.H. |date = November 1936 |magazine = California Highways and Public Works |volume = 14 |issue = 11 |pages = 6–8 |publisher = California Department of Public Works |access-date = December 20, 2017 }} Once the excavation was complete, the upper deck was placed and the interior ceiling above the upper deck was lined with tiles. The last concrete poured during the construction of the Bay Bridge was part of the upper deck lining in late summer 1936. This included the emplacement of regularly spaced refuge bays ("deadman holes") along the south wall of the lower deck tunnel, escape alcoves common in all railway tunnels into which track maintenance workers could duck if a train came along.{{cite web |url=http://www.dot.ca.gov/hq/esc/tollbridge/SFOBB/EastSpan/012024/MaterialsHandout/cd1/asbuilt/Yerba%20Buena%20Crossing%20%28Contract%20No.%2004-5%29.pdf#page=28 |publisher=State of California, Dept. of Public Works |title=Tunnel Section and Details, Yerba Buena Crossing, San Francisco-Oakland Bay Bridge, Sup. Drawing No. 19A |date=June 1934 |archive-url=https://web.archive.org/web/20030418115859/http://www.dot.ca.gov/hq/esc/tollbridge/SFOBB/EastSpan/012024/MaterialsHandout/cd1/asbuilt/Yerba%20Buena%20Crossing%20(Contract%20No.%2004-5).pdf |url-status=dead |archive-date=April 18, 2003}} These remain and are visible to eastbound motorists today.

The completed tunnel bore is {{convert|76|ft}} wide and {{convert|58|ft}} high overall, and the dimensions of the tunnel interior are {{convert|66|ft}} wide and {{convert|53|ft}} high. In 1936, it was hailed as the world's largest-bore tunnel.{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=MT19361110.2.10 |title = Ready great fetes start bridge trips |date = November 10, 1936 |newspaper = Madera Tribune |access-date = December 20, 2017 }}{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=MT19361112.2.112.1 |title = Facts about the San Francisco-Oakland Bay Bridge |date = November 12, 1936 |newspaper = Madera Tribune |access-date = December 20, 2017 |quote = The Yerba Buena Island Tunnel, 65 feel wide by 52 feet high, through which a four-story building could be towed upright, is the largest diameter bore in the world. }} The cross-sectional area of the upper half is {{convert|1500|sqft}}, and the lower half is {{convert|1000|sqft}}.

{{multiple image

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| header = Yerba Buena Tunnel cross-sections (facing east)

| image1 = YBT (1938).svg

| alt1 = A schematic illustration of the cross-section of the Yerba Buena Tunnel in 1938, section taken facing east. In 1938, the tunnel carried six bidirectional lanes of automobile traffic on the upper deck, three lanes of truck traffic on the north side of the lower deck, and two tracks for electrified rail service on the south side of the lower deck.

| caption1 = 1938

| image2 = YBT (1962).svg

| alt2 = A schematic illustration of the cross-section of the Yerba Buena Tunnel in 1962, section taken facing east. In 1961–62, the tunnel was reconstructed after rail service stopped in 1958. The upper and lower decks were lowered, and the upper deck now carries five lanes of mixed auto/truck traffic westbound, while the lower deck carries five lanes of mixed traffic eastbound.

| caption2 = 1962

| footer = Redrawn from HAER drawings by Zachary Goodman

}}

The tunnel has two decks. As originally completed, the upper deck was reserved for automobile traffic, and carried six lanes, each {{convert|9|ft|8|in|m}} wide. The lower deck was further divided into three lanes of traffic for heavy trucks (each {{convert|10|ft|4|in|disp=sqbr}} wide), and two railroad tracks on the south side ({{convert|27|ft|m|disp=sqbr}} wide for both tracks).{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1935_sep.pdf |title = Yerba Buena Tunnel Bore Completed with Removal of all Core |date = December 1935 |magazine = California Highways and Public Works |volume = 13 |issue = 12 |pages = 26–27 |publisher = California Department of Public Works |access-date = December 20, 2017 }} The initial design in 1932 called for the two rail tracks to flank a central truck deck on the lower level.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1932_jan.pdf |title = Transbay Bridge Tunnel Unit to be World's Largest Cross-Section Bore |last = Purcell |first = C.H. |date = January 1932 |magazine = California Highways and Public Works |volume = 10 |issue = 1 |pages = 6–7;17 |publisher = California Department of Public Works |access-date = December 20, 2017 }} After Key System trains stopped running over the bridge in 1958, bids were opened on October 11, 1960, to rebuild the tunnel. The rebuild consisted of multiple stages of work:

1. Remove Key System rails, lower rail deck and repave
2. Lower the truck traffic half of the lower deck by {{convert|3|ft}} and repave
3. Remove center columns supporting upper deck
4. Lower the upper deck by {{convert|16|in}} by placing precast concrete units

After the reconstruction, the tunnel would handle only road traffic. The upper deck was lowered to accommodate heavy truck traffic, as each deck would now carry five lanes of unidirectional traffic. The upper deck was dedicated to westbound traffic, and the lower deck was dedicated to eastbound traffic.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1960_sepoct.pdf |title = Bid Opening Set for Yerba Buena Tunnel |date = September–October 1960 |magazine = California Highways and Public Works |volume = 39 |issue = 9–10 |pages = 40 |publisher = California Department of Public Works |access-date = December 20, 2017 |archive-url = https://web.archive.org/web/20160826093718/http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1960_sepoct.pdf |archive-date = August 26, 2016 |url-status = live }} The impact to traffic during reconstruction of the tunnel was minimized mainly by working outside normal commuting hours and through the use of a portable steel bridge {{convert|26|ft}} long and {{convert|58|ft}} wide, designed to fit between the curbs of the existing upper deck.{{cite magazine |url = http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1962_janfeb.pdf |title = Bay Bridge: Second Phase of Reconstruction Nearing Completion |author = Raab, N.C. |date = January–February 1962 |magazine = California Highways and Public Works |volume = 41 |issue = 1–2 |pages = 36–43 |publisher = California Department of Public Works |access-date = December 20, 2017 |archive-url = https://web.archive.org/web/20171203082923/http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1962_janfeb.pdf |archive-date = December 3, 2017 |url-status = live }} The bridge spanned the gap between the new upper deck and old upper deck, and the overall elevation change of {{convert|26|in}} caused drivers to slow to {{convert|15|mph|km/h}}, resulting in traffic jams.{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=MT19611128.2.26 |title = Commuters Learning to Live with Bay Bridge Tunnel Hump |agency = United Press International |date = November 28, 1961 |newspaper = Madera Tribune |access-date = December 20, 2017 }}{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=MT19611228.2.62 |title = Bay Bridge Hump Work On |agency = United Press International |date = December 28, 1961 |newspaper = Madera Tribune |access-date = December 20, 2017 }} The first accident caused by "The Hump", the nickname the bridge acquired after prominent warning signs advertising its presence, occurred just twelve minutes after it was first deployed on November 25, 1961.

The new precast upper deck units were each {{convert |7|ft|8|in}} long, and were installed in two halves. One side of each half rested on a temporary falsework erected in the middle of the lower deck, and the other side rested on the shoulder of the tunnel wall previously used to support the old upper deck. After the two halves were fastened together, a steel form was used to close the {{convert|1|ft|6|in|m|adj=mid|-wide}} gap between halves, and concrete was poured in the gap. The upper deck rests on {{convert|12|in|cm|adj=mid|-wide}} shoulders built into the tunnel wall, padded by {{convert|1/2|in|cm|adj=mid|-thick}} Masonite.

The planned completion date for tunnel reconstruction was July 1962,{{cite news |url = https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=SCS19611227.1.1 |title = Bay Bridge Hump Is Inspected By Works Director |agency = Associated Press |date = December 27, 1961 |newspaper = Santa Cruz Sentinel |access-date = December 20, 2017 }} but "The Hump" was not dismantled until October 27, 1962. The San Francisco Chronicle marked the occasion by quipping "[The Hump] produced more jams than Grandma ever made."{{cite news |url = http://www.sfgate.com/news/article/PAGE-ONE-Bridge-Has-Been-on-This-Road-Before-2995141.php |title = Bridge Has Been on This Road Before / Bay span's revamp was a mess in '60s |last = Nolte |first = Carl |date = February 5, 1996 |newspaper = San Francisco Chronicle |access-date = December 21, 2017 }} After reconstruction, both the upper and lower decks featured {{convert|16|ft}} of vertical clearance. Upper deck clearance is restricted by the tunnel portal, and lower deck clearance is restricted by the upper deck.

File:Architect and engineer (1933) (14595236739).jpg|Study of West Portal (1933)

File:I think i died and went to heaven (6348398762).jpg|Exiting western portal (2011)

File:Yerba Buena tunnel, San Francisco Bay Bridge, going east, to Oakland (9671027093).jpg|Lower deck, showing "deadman" holes on south side (2013)

File:Frank Deras Jr., Photographer May 1998 AERIAL VIEW OF YERBA BUENA EAST TUNNEL PORTAL AND VIADUCT, FACING SOUTH. - San Francisco Oakland Bay Bridge, Spanning San Francisco HAER CAL,38-SANFRA,141-225.tif|Westbound traffic approaches tunnel (1998)

File:Frank Deras Jr., Photographer May 1998 AERIAL VIEW OF SUSPENSION BRIDGE STIFFENING TRUSS, YERBA BUENA ANCHORAGE, AND YERBA BUENA TUNNEL, FACING NORTH. - San Francisco HAER CAL,38-SANFRA,141-178.tif|Westbound traffic departs West Portal (1998)

File:Yerba Buena Island tunnel.jpg|Westbound traffic in tunnel (2006)

File:Yerba Buena Tunnel (3017687683).jpg|Westbound night traffic (2008)

{{reflist}}

{{commons category|Yerba Buena Tunnel}}

• {{Structurae |id=20023793 |name=Yerba Buena Tunnel}}
• {{cite web |url = https://bridgehunter.com/ca/san-francisco/340004/ |title = Yerba Buena Tunnel |author = |date = October 2, 2014 |website = Bridgehunter |access-date = December 20, 2017 }}
• {{cite web |url = http://sflib1.sfpl.org:82/search?/dBridges+Bay/dbridges+bay/1%2C43%2C756%2CE/2exact&FF=dbridges+bay+yerba+buena+tunnel&1%2C11%2C |title = Folder: Bridges, Bay, Yerba Buena Tunnel |author = |date = 1936–1961 |publisher = San Francisco History Center, San Francisco Public Library |access-date = December 20, 2017 }}
• {{cite web |url = http://sflib1.sfpl.org:82/search?/dBridges+--+Bay+--+Construction+--+Yerba+Buena+Tun/dbridges+bay+construction+yerba+buena+tunnel/-3%2C-1%2C0%2CE/2exact&FF=dbridges+bay+construction+yerba+buena+tunnel&1%2C23%2C |title = Folder: Bridges, Bay, Construction, Yerba Buena Tunnel |author = |date = 1934–1936 |publisher = San Francisco History Center, San Francisco Public Library |access-date = December 20, 2017 }}

{{Bay Area tunnels}}

Category:Road tunnels in California

Category:Tunnels in San Francisco

Category:Tunnels completed in 1936

Category:1936 establishments in California