Editing Holland Tunnel (section)

====Ventilation system====
{{multiple image
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| image1    = New York Land Ventilation Building south side 119149pv.jpg
| width1    = 228
| caption1  = 1985 shot of the tower at the New York Land Ventilation Building, one of four such towers
| image2    = HollandTunnelVentTowerHudRivJC crop.jpg
| width2    = 200
| caption2  = The [[Hudson River]] ventilation tower in [[Jersey City, New Jersey|Jersey City]]
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The most significant design aspect of the Holland Tunnel is its ventilation system; it is served by four ventilation towers designed by Norwegian architect Erling Owre.<ref>{{citation|last=Gomez|first=John|title=Brilliant design in Modernist towers that ventilate the Holland Tunnel: Legends & Landmarks|date=April 10, 2012|url=http://www.nj.com/jjournal-news/index.ssf/2012/04/brilliant_design_in_modernist.html|newspaper=The Jersey Journal|access-date=August 12, 2012|archive-date=June 14, 2012|archive-url=https://web.archive.org/web/20120614164312/http://www.nj.com/jjournal-news/index.ssf/2012/04/brilliant_design_in_modernist.html|url-status=live}}</ref>  At the time of its construction, underwater tunnels were a well-established part of civil engineering, but no long vehicular tunnels had been built, as all of the existing tunnels under New York City waterways carried only railroads and subways. These tubes did not have as much of a need for ventilation, since the trains that used the tubes were required to be electrically powered, and thus emitted very little pollution.<ref name="nris" />{{rp|10}}<ref name="nyt-1920-10-10" /> On the other hand, the traffic in the Holland Tunnel consisted mostly of gasoline-driven vehicles, and ventilation was required to evacuate the carbon monoxide emissions, which would otherwise asphyxiate the drivers.<ref name="nris" />{{rp|10}}<ref name="saga2">{{cite book | last=Bjork | first=K. | title=Saga in Steel and Concrete – Norwegian Engineers in America | publisher=Read Books | year=2007 | isbn=978-1-4067-6829-9 | url=https://books.google.com/books?id=mAP4zZTvdfEC | access-date=May 29, 2018 | archive-date=February 25, 2023 | archive-url=https://web.archive.org/web/20230225232914/https://books.google.com/books?id=mAP4zZTvdfEC | url-status=live }}</ref>{{rp|181–202}}<ref>
* {{Cite news|title=Studies and Methods Adopted for Ventilating the Holland Vehicular Tunnels|date=June 9, 1927|periodical=Engineering News-Record|volume=98|pages=934–939}}
* {{Cite news|title=Ventilating the Holland Vehicular Tunnel|date=August 1926|periodical=Heating and Ventilating Magazine|issue=79|volume=23}}
* {{cite conference|last=Singstad|first=Ole|title=Ventilation of Vehicular Tunnels|volume=9|pages=381–399|book-title=Proceedings of the World Engineering Congress}}
* {{Cite news|title=Development of the ventilation system of the Holland Tunnel|last=Davis|first=A.&nbsp;C.|date=October 1930|periodical=Heating, Piping and Air Conditioning|volume=2|pages=866–874}}
* {{cite report|last1=Fieldner|first1=A.C.|last2=Henderson|first2=Y.|last3=Paul|first3=J.W.|last4=others|date=February 1927|title=Ventilation of vehicular tunnels (Report of U.S. Bureau of Mines to New York State Bridge and Tunnel Commission and New Jersey State Bridge and Tunnel Commission)|publisher=American Society of Heating and Ventilating Engineers}}</ref> There were very few tunnels at that time that were not used by rail traffic; the most notable of these non-rail tunnels, the [[Blackwall Tunnel]] and [[Rotherhithe Tunnel]] in London, did not need mechanical ventilation.<ref name="nris" />{{rp|10}} However, a tunnel of the Hudson River Tunnel's length required an efficient method of ventilation, so Chief Engineer Singstad pioneered a system of ventilating the tunnel transversely (perpendicular to the tubes).<ref name="Krebs 1969">{{cite news|url=https://www.nytimes.com/1969/12/09/archives/ole-singstad-87-master-builder-of-underwater-tunnels-is-dead-ole.html|title=Ole Singstad, 87, Master Builder Of Underwater Tunnels, Is Dead|last=Krebs|first=Albin|date=December 9, 1969|newspaper=The New York Times|issn=0362-4331|access-date=May 29, 2010|archive-date=April 10, 2018|archive-url=https://web.archive.org/web/20180410072019/https://www.nytimes.com/1969/12/09/archives/ole-singstad-87-master-builder-of-underwater-tunnels-is-dead-ole.html|url-status=live}}</ref><ref name="nyt-1924-02-17">{{Cite news|url=https://www.nytimes.com/1924/02/17/archives/pure-air-is-assured-for-the-vehicular-tunnel-there-will-be-no.html|title=Pure Air Is Assured For The Vehicular Tunnel|date=February 17, 1924|work=The New York Times|issn=0362-4331|access-date=May 6, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506104412/https://www.nytimes.com/1924/02/17/archives/pure-air-is-assured-for-the-vehicular-tunnel-there-will-be-no.html|url-status=live}}</ref>

In October 1920, General [[George R. Dyer]], the chairman of the New York Tunnel Commission, published a report in which he wrote that Singstad had devised a feasible ventilation system for the Hudson River Tunnel.<ref name="nyt-1920-10-10">{{Cite news|url=https://www.nytimes.com/1920/10/10/archives/solve-ventilation-of-vehicular-tube-gen-dyer-says-that-experts-have.html|title=Solve Ventilation of Vehicular Tube|date=October 10, 1920|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 5, 2018|archive-url=https://web.archive.org/web/20180505135114/https://www.nytimes.com/1920/10/10/archives/solve-ventilation-of-vehicular-tube-gen-dyer-says-that-experts-have.html|url-status=live}}</ref> Working with [[Yale University]], the [[University of Illinois system|University of Illinois]], and the [[United States Bureau of Mines]], Singstad built a test tunnel in the bureau's [[Experimental Mine, U.S. Bureau of Mines|experimental mine]] at [[Bruceton, Pennsylvania]], measuring over {{convert|400|ft|m|0}} long, where cars were lined up with engines running. Volunteer students were supervised as they breathed the exhaust in order to confirm air flows and tolerable carbon monoxide levels by simulating different traffic conditions, including backups.<ref name="nyt-1921-10-30">{{Cite news|url=https://www.nytimes.com/1921/10/30/archives/tests-show-safety-of-vehicle-tunnel-ventilating-system-for-proposed.html|title=Tests Show Safety Of Vehicle Tunnel|date=October 30, 1921|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 5, 2018|archive-url=https://web.archive.org/web/20180505210517/https://www.nytimes.com/1921/10/30/archives/tests-show-safety-of-vehicle-tunnel-ventilating-system-for-proposed.html|url-status=live}}</ref><ref name="nyt-1924-02-17" /> The University of Illinois, which had hired the only professors of ventilation in the United States, built an experimental {{convert|300|ft|m|-long|adj=mid}} ventilation duct at [[University of Illinois at Urbana–Champaign|its Urbana campus]] to test air flows.<ref name="nyt-1924-02-17" /><ref>{{Cite news|url=https://www.nytimes.com/1921/04/03/archives/study-tube-ventilation-model-of-hudson-river-tunnel-being-built-by.html|title=Study Tube Ventilation|date=April 3, 1921|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 5, 2018|archive-url=https://web.archive.org/web/20180505142032/https://www.nytimes.com/1921/04/03/archives/study-tube-ventilation-model-of-hudson-river-tunnel-being-built-by.html|url-status=live}}</ref> In October 1921, Singstad concluded that a conventional, longitudinal ventilation system would have to be pressurized to an air flow rate of {{convert|27|m3/s|0|sp=us}} along the tunnel.<ref name="nyt-1921-10-30" /> On the other hand, the tunnel could be adequately ventilated transversely if the compartment carrying the tube's roadway was placed in between two [[Plenum chamber|plenums]]. A lower plenum below the roadway floor could supply fresh air, and an upper plenum above the ceiling could exhaust fumes at regular intervals.<ref name="nyt-1921-10-30" /><ref name="nyt-1926-11-28" />

Two thousand tests were performed with the ventilation system prototype.<ref name="New York Sun 1926" /> The system was determined to be of sufficiently low cost, relative to the safety benefits, that it was ultimately integrated into the tunnel's design.<ref name="nyt-1924-02-17" /> By the time the tunnel was in service, the average carbon monoxide content in both tunnels was 0.69 parts per 10,000 parts of air. The highest recorded carbon monoxide level in the Holland Tunnel was 1.60 parts per 10,000, well below the permissible maximum of 4 parts per 10,000.<ref name="New York Sun 1927" /><ref name="saga2"/> The public and the press proclaimed air conditions were better in the tubes than in some streets of New York City; after the tunnel opened, Singstad stated that the carbon monoxide content in the tubes were half of those recorded on the streets.<ref name="saga2" /><ref>{{Cite news|url=https://www.nytimes.com/1927/12/09/archives/tunnel-air-called-purest-singstad-says-its-monoxide-is-half-what.html|title=Tunnel Air Called Purest|date=December 9, 1927|work=The New York Times|issn=0362-4331|access-date=May 10, 2018|archive-date=May 16, 2018|archive-url=https://web.archive.org/web/20180516103005/https://www.nytimes.com/1927/12/09/archives/tunnel-air-called-purest-singstad-says-its-monoxide-is-half-what.html|url-status=live}}</ref>