Editing Caldecott Tunnel (section)

==History==
[[File:Caldecott Tunnel Twin Bores.jpg|thumb|Traffic patterns in 1937]]
In the 19th century, traffic over the [[Berkeley Hills]] in this area went up Harwood Canyon, now known as Claremont Canyon (behind the [[Claremont Resort|Claremont Hotel]]). The road leading up the canyon from the west was initially called Harwood's Road, later changed to [[Telegraph Avenue|Telegraph Road]], and finally, Claremont. The road on the other side of the hills became known as Fish Ranch Road, its current name, some time after 1870, the year the Oakland Trout Company incorporated its fish and frog farm in the vicinity.<ref>[https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=SDU18710102.2.24 Sacramento Daily Union, 2 January 1871, p.2]</ref> An inn and stage coach stop called the Summit House once existed at the summit.

The idea of a tunnel through the hills began as early as 1860. In that year, the idea was proposed and rejected by the citizens of Alameda and Contra Costa Counties. It was revived in 1871 in a private attempt led by L.W. Kennedy which however failed after boring about 200 feet into the hills from the east side of the hills above the location of today's Caldecott Tunnel when water was struck, washing out the work.  Bankruptcy followed and the effort, which came to be known as the "old Kennedy tunnel" was abandoned. A franchise was subsequently granted to a group of developers who passed the franchise onto another group. The proposal languished until the turn of the century.<ref>{{cite book | url=https://archive.org/details/historyofcontrco00munrrich| title=History of Contra Costa County, California | publisher=W.A. Slocum and Company | page=[https://archive.org/details/historyofcontrco00munrrich/page/135 135] | year=1882}}</ref><ref>[https://chroniclingamerica.loc.gov/lccn/sn85066387/1902-11-14/ed-1/seq-9/#date1=1789&index=3&rows=20&words=CONTRA+Contra+COSTA+Costa+Counties+COUNTIES+County&searchType=basic&sequence=0&state=California&date2=1963&proxtext=contra+costa+county&y=17&x=11&dateFilterType=yearRange&page=1 "Old Road That Ruined Three Pioneers To Be Completed", ''San Francisco Call'', November 14, 1902, p.9]</ref>

Just before the end of the 19th century, the tunnel idea was revived and discussed by business and government representatives of Contra Costa and Alameda Counties.<ref>[https://localwiki.org/oakland/Kennedy_Tunnel/_files/Oakland%20Trib%20-%20May%2024,%201897.pdf/_info/ "The Work Begun",  ''Oakland Tribune'', May 24, 1897]</ref>  These discussions led to a new tunnel construction project at the approximate location of the old Kennedy tunnel attempt.  The work on the Contra Costa side proceeded based on the old tunnel alignment while work on the Alameda County side started from the top of Temescal Canyon.  On the west side, the project involved the construction of a proper approach road.  The new road, dubbed "Tunnel Road", was built from the top of Russell Street in Berkeley (later realigned with Ashby Avenue) at the foot of Claremont Canyon and ran around the spur separating that canyon from Temescal Canyon, climbing along the slope of the spur to the summit of the Berkeley Hills until it reached the west portal of the new tunnel.<ref>[https://www.newspapers.com/image/72451934/?fcfToken=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmcmVlLXZpZXctaWQiOjcyNDUxOTM0LCJpYXQiOjE2ODMyMjc3NTksImV4cCI6MTY4MzMxNDE1OX0.3QiSIsI4rmQzoWmIaiRoXboHsuBUIhzI_5suRx_ykxM "Work of Supervisors on Inter-County Road", ''Oakland Tribune'', 04 Nov 1903, Page 3]</ref>  The west end of the tunnel was at about {{coord|37.8561|-122.2137|display=inline}} while the east end of the tunnel is now in private property owned by the East Bay Regional Park District, on the former site of the Canary Cafe. 
[[File:"Scene at Dedication of New Tunnel" Oakland Tribune, November 4, 1903.jpg|thumb|left|"Scene at Dedication of New Tunnel" ''Oakland Tribune'', November 4, 1903]]
The tunnel was dedicated on November 4, 1903 as the "Inter-County Tunnel".<ref>[https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=SFC19031105.2.30&srpos=221&e=-------en--20--1--txt-txIN-------- ''San Francisco Call'', Volume 94, Number 158, 5 November 1903]</ref> A system of lighting a small fire with a newspaper was used to control this one-way traffic. The tunnel height was increased in 1915 by 3 feet to accommodate larger vehicles.<ref>{{cite web | url=http://www.lafayettehistory.org/pict0014ChangeN.html | title=Lafayette: A Pictorial History | publisher=Lafayette Historical Society | access-date=October 8, 2013 | archive-url=https://web.archive.org/web/20130928030304/http://www.lafayettehistory.org/pict0014ChangeN.html | archive-date=September 28, 2013 | url-status=dead | df=mdy-all }}</ref> After the new Broadway (Caldecott) tunnel was opened at the end of 1937, the old tunnel was used mostly by pedestrians until it was sealed in 1947.<ref name="baycitizen">{{cite news | url=http://www.baycitizen.org/local-intelligence/story/local-intelligence-kennedy-tunnel/ | title=Local Intelligence: Kennedy Tunnel | work=Bay Citizen | first=Louise | last=Rafkin | date=October 1, 2011 | access-date=October 8, 2013 | archive-url=https://web.archive.org/web/20120103235151/http://www.baycitizen.org/local-intelligence/story/local-intelligence-kennedy-tunnel/ | archive-date=January 3, 2012 | url-status=dead }}</ref>

===Original twin bores===
In November 1926, the Counties of Alameda and Contra Costa, and the City of Oakland agreed to the construction of a new tunnel through the Berkeley Hills to replace the old, small, decrepit and increasingly inadequate existing tunnel.<ref>[https://archive.org/stream/californiahighwa193436calirich#page/n163/mode/2up/search/Berkeley ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, May, 1934, p.16]</ref> In 1929, Alameda and Contra Costa County formed Joint Highway District 13 to accomplish this goal.<ref>[https://archive.org/stream/cavol3940liforniahigh6061wa00calirich#page/n263/mode/2up ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, Jul-August, 1960, p.31]</ref> Surveys and preliminary work on the approaches began in 1931.<ref>[https://archive.org/stream/california193638highwacalirich#page/n597 ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, December, 1937, p.12]</ref><ref>[https://archive.org/stream/californiahighwa193436calirich#page/n163/mode/2up ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, May, 1934, p.15]</ref>

On June 17, 1934, construction of the first two bores of the Caldecott Tunnel began.<ref>[https://archive.org/stream/californiahighwa193436calirich#page/n235/mode/2up ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, July, 1934, p.16]</ref>

The project included an extension of Broadway from its existing termination point below the hills some two miles from the planned west portal of the new tunnel. This required some major earth-moving efforts, both cutting and filling as well as buttressing, especially up in Temescal Canyon.  This included filling in one of the inlets of Lake Temescal as well as part of the upper canyon where Broadway was to run.

The entire project was completed in 1937, and the tunnel opened to traffic on December 5 of that year.<ref>[https://archive.org/stream/california193638highwacalirich#page/n589/ ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, December, 1937, p.4]</ref> The tunnel was named the '''Broadway Low Level Tunnel''' (commonly shortened to '''Broadway Tunnel'''), since the principal through access was from Broadway in Oakland, and was located below the portal of the old Inter County Tunnel. However, access from Ashby Avenue was retained as it was designated the connecting thoroughfare from the [[Eastshore Highway]] (re-engineered as a freeway in the mid 1950s) and the new [[San Francisco–Oakland Bay Bridge]], and dubbed State Highway 24. The approach to the east portal on the other side of the Berkeley Hills was via Mount Diablo Boulevard, also at that time part of State Highway 24.

In 1960, the Broadway Low Level Tunnel was renamed, becoming the Caldecott Tunnel.<ref>[https://archive.org/details/cavol3940liforniahigh6061wa00calirich/page/n369 ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, Vol.39, Nos.9-10, September-October, 1960, p.60]</ref>

===Third bore and traffic reversal===
[[File:Caldecott Tunnel.jpg|right|thumb|The Caldecott Tunnel prior to the construction of the fourth bore as seen from the western end. From left to right: Bores 3, 2, and 1. Bore 2 was serving westbound traffic at the time of this photograph.]]
By 1960, the Division of Highways had rebuilt the eastern approach to the tunnel into a freeway. With Contra Costa County accessible by freeway, its change from an agricultural community into a major suburb accelerated.

The Division of Highways purchased sufficient right-of-way to the north of the existing twin bores to build another pair of bores. Given the traffic counts and the expense of tunnel construction, the construction of two additional bores would have been seen as unnecessary and extravagant. However, with the traffic count exceeding 50,000 vehicles per day, the state embarked on a project to build a third bore at the Caldecott Tunnel.<ref>[https://archive.org/details/cavol3940liforniahigh6061wa00calirich/page/n263 ''California Highways and Public Works'', Official Journal of the Division of Highways, Department of Public Works, State of California, Vol.39, Nos.7-8, July-August, 1960, p.31]</ref>

The project broke ground in 1960 and was opened to traffic in October 1964. When the third bore was opened, the other bores were closed one at a time for maintenance, including the installation of a continuous row of fluorescent lights. The new third bore made it possible to provide four lanes to accommodate the heavier commute-direction traffic by [[Reversible lane|reversing the traffic flow]] of the middle bore.

The third bore also brought new technology to the tunnel with the installation of the "pop-up" lane control. Plastic lane [[delineator]]s were set in tubes within the pavement. With the touch of a button, water would fill tubes to cause the delineators to pop up from the pavement; the middle bore was closed to one direction of travel, while opening it to another. During the week, the middle bore of the Caldecott was reversed between 2:00 am and 5:00 am to favor westbound traffic, and then switched again sometime between 11:30 am and noon to favor eastbound traffic. Ballgames, concerts and other events made balancing weekend traffic through the tunnel very difficult. It was not uncommon to reverse the middle bore six times on a Saturday or Sunday. The pop-up system still required substantial manpower to implement. While it did eliminate the need to set down individual cones to separate traffic, Caltrans maintenance workers had to direct traffic out of the closing lanes to prevent vehicles from getting caught on the wrong side of the pop-up delineators.<ref>{{cite web | url=http://www.caldecott-tunnel.org/project-overview/history-caldecott | title=History of the Caldecott | work=The Caldecott Tunnel Fourth Bore Project | access-date=October 8, 2013 | archive-url=https://web.archive.org/web/20140202105048/http://www.caldecott-tunnel.org/project-overview/history-caldecott | archive-date=February 2, 2014 | url-status=dead | df=mdy-all }}</ref>

A portion of the material excavated for the third bore was used in the construction of embankments for the MacArthur Freeway project between the MacArthur Maze and Broadway in Oakland.<ref>[http://libraryarchives.metro.net/DPGTL/Californiahighways/chpw_1960_marapr.pdf ''California Highways and Public Works'', March-April, 1960, p.9]</ref>

In the late 1960s, the [[Grove-Shafter Freeway]] was completed and replaced Broadway as the main route to the Caldecott Tunnel from Oakland as well as replacing Ashby for traffic coming from San Francisco. Ashby Avenue and Tunnel Road were redesignated [[State Route 13 (California)|State Highway 13]] and aligned with the new Warren Freeway through the Montclair District of Oakland. The Grove-Shafter Freeway was then designated State Highway 24. In 1980, the freeway was renamed after [[William Byron Rumford]].

===Tunnel fire===
{{main|Caldecott Tunnel fire}}
On April 7, 1982, an accident involving a gasoline [[tanker truck]] in the third (then-northernmost) bore set off the [[Caldecott Tunnel fire]].<ref>{{cite web | first=Murilee | last=Martin | url=http://jalopnik.com/cars/retro/25-years-since-the-great-caldecott-tunnel-fire-252688.php | title=25 Years Since The Great Caldecott Tunnel Fire | publisher=Jalopnik | date=April 16, 2007 | access-date=January 23, 2010}}</ref> The accident caused major damage and the bore was closed to traffic for several months while repairs were made, with traffic temporarily reverting to the pre-third-bore configuration. During the fire, the tunnel acted as a natural chimney, venting the smoke, flames and heat uphill towards the eastern entrance to the tunnel. The accident and fire killed seven people, most of whom were overcome by [[Smoke inhalation|toxic smoke]]. The fire occurred shortly after midnight when there were few cars in the tunnel; had it occurred during normal commute hours, hundreds could have died. As a result of the fire, it is now illegal to transport hazardous material in a tanker truck through the tunnel, except between the light-traffic hours of 3:00 am and 5:00 am.<ref>{{cite web|url=http://www.dmv.ca.gov/pubs/vctop/d13/vc31301.htm | title=Vehicle Code Section 31301 - Caldecott Tunnel Restriction | publisher=California Department of Motor Vehicles | date=September 20, 1982 | access-date=January 23, 2010}}</ref>

===Oakland firestorm===
On October 20, 1991, the catastrophic [[1991 Oakland firestorm|Oakland firestorm]] started on the ridge north of the Caldecott Tunnel. The fire spread quickly west down both sides of the west portal of the tunnel and jumped from the East to the West side of highway 13, eventually killing 25 people and destroying over 3,000 homes, apartments and condominiums.

===Awards===
The Caldecott Tunnel was designated a City of Oakland Landmark in 1980, and received a Preservation Award from the Art Deco Society of California in 1993.

===Fourth bore===
To relieve traffic congestion in the reverse commute direction, the [[California Department of Transportation]] began planning for a fourth bore in 2000. In 2007, the [[California Transportation Commission]] approved the final funding needed to build the fourth bore.<ref>{{cite web | url=http://www.mtc.ca.gov/funding/infrastructure/Adopted_CMIA_Bay_Area_Projects.pdf | title=Corridor Mobility Improvement Account (CMIA) as adopted by California Transportation Commission (CTC) — February 28, 2007: San Francisco Bay Area Projects | publisher=Metropolitan Transportation Commission | access-date=January 20, 2014 | archive-url=https://web.archive.org/web/20140123231959/http://www.mtc.ca.gov/funding/infrastructure/Adopted_CMIA_Bay_Area_Projects.pdf | archive-date=January 23, 2014 | url-status=dead | df=mdy-all }}</ref> Construction started in 2010.<ref>{{cite news | url=http://www.sfgate.com/bayarea/article/Work-begins-on-Caldecott-Tunnel-s-4th-bore-3275155.php | title=Work begins on Caldecott Tunnel's 4th bore | first=Michael | last=Cabanatuan | work=San Francisco Chronicle | date=January 23, 2010 | access-date=January 20, 2014}}</ref> Commencement of the project was stalled as a result of the [[financial crisis of 2007–2008]], but was quickly back on track as a beneficiary of President Obama's American Recovery and Reinvestment Act of 2009 (ARRA).<ref>{{Cite web|url=http://mtc.ca.gov/whats-happening/news/tunneling-begins-420-million-caldecott-tunnel-fourth-bore-project|title = Tunneling Begins on $420 Million Caldecott Tunnel Fourth Bore Project &#124; Metropolitan Transportation Commission| date=June 3, 2015 }}</ref><ref>{{Cite web|url=https://www.fhwa.dot.gov/pressroom/fhwa1031.cfm|title = Press Release: Recovery Act-Funded Excavation Begins on Caldecott Tunnel's Fourth Bore, 8/9/2010 &#124; Press Releases}}</ref> Construction got underway until completion in 2013.<ref>{{cite news | url=http://www.sfgate.com/bayarea/article/Breakthrough-for-Caldecott-Tunnel-s-new-4th-bore-2339892.php | title=Breakthrough for Caldecott Tunnel's new 4th bore | first=Michael | last=Cabanatuan | work=San Francisco Chronicle | date=December 1, 2011 | access-date=January 20, 2014}}</ref><ref>{{cite news | url=http://www.sfgate.com/bayarea/article/Caldecott-Tunnel-excavation-finished-3783185.php | title=Caldecott tunnel excavation completed | first=Michael | last=Cabanatuan | work=San Francisco Chronicle | date=August 13, 2012 | access-date=October 8, 2013}}</ref><ref>{{cite news | url=http://www.sfgate.com/bayarea/article/Caldecott-Tunnel-fourth-bore-opens-4986581.php | title= Caldecott Tunnel fourth bore opens | first=Michael | last=Cabanatuan | work=San Francisco Chronicle | date=November 16, 2013 | access-date=January 20, 2014}}</ref> Much of the excavated material from the bore was trucked to [[Treasure Island, San Francisco|Treasure Island]] for use in soil augmentation and remediation during the subsequent redevelopment of the island.<ref>{{cite news |last1=Cuff |first1=Denis |title=Caldecott Tunnel forth bore to ease traffic backups during reverse commute |url=https://www.mercurynews.com/2013/11/13/caldecott-tunnel-forth-bore-to-ease-traffic-backups-during-reverse-commute/ |access-date=29 December 2018 |work=Mercury News |date=13 November 2013}}</ref>

The fourth bore contains a roadway with two {{Convert|12|ft|m|1|adj=mid|-wide}} traffic lanes, one {{Convert|10|ft|m|1|adj=mid|-wide}} shoulder, and one {{Convert|2|ft|m|1|adj=mid|-wide}} shoulder,<ref>{{cite web |url=https://mtc.ca.gov/sites/default/files/Tunneling_FactSheet.pdf |accessdate=4 December 2021 |title=Project Fact Sheet |website=mtc.ca.gov | date=April 2010 }}</ref> ventilation, air and traffic monitoring systems, traffic lights, and electronic message boards.<ref>{{cite journal |last=Cardno |first=Catherine A. |date=February 2014 |title=Safe passage |journal=Civil Engineering |publisher=American Society of Civil Engineers |pages=60–65 }}</ref> There are emergency exits to the third bore. When the fourth bore was opened to traffic, the need for the daily traffic reversal was eliminated; two bores (four lanes) serve each direction at all times, although individual bores may be closed during periods of light use for maintenance purposes.<ref>{{cite web | url=http://www.caldecott-tunnel.org/project-overview/schedule | title=Caldecott Tunnel Fourth Bore Project Schedule | work=The Caldecott Tunnel Fourth Bore Project | access-date=October 8, 2013 | archive-url=https://web.archive.org/web/20140202105427/http://www.caldecott-tunnel.org/project-overview/schedule | archive-date=February 2, 2014 | url-status=dead | df=mdy-all }}</ref>