Editing Holland Tunnel (section)

=== Construction ===
The first bid for constructing the Hudson River Tunnel, a contract for digging two of the tunnel's eight planned shafts, was advertised in September 1920.<ref>{{Cite news|url=https://www.nytimes.com/1920/09/22/archives/first-bids-opened-for-vehicular-tube-lowest-figures-for.html|title=First Bids Opened For Vehicular Tube|date=September 22, 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/20180505142034/https://www.nytimes.com/1920/09/22/archives/first-bids-opened-for-vehicular-tube-lowest-figures-for.html|url-status=live}}</ref> A groundbreaking for the Hudson River Tunnel's ventilation shaft, which marked the official start of construction on the tunnel, occurred on October 12, 1920, at [[Canal Street (Manhattan)|Canal]] and [[Washington Street (Manhattan)|Washington Streets]] on the Manhattan side.<ref>{{Cite news|url=https://www.nytimes.com/1920/10/13/archives/ground-is-broken-for-vehicular-tube-tunnel-is-acclaimed-as.html|title=Ground Is Broken For Vehicular Tube|date=October 13, 1920|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110039/https://www.nytimes.com/1920/10/13/archives/ground-is-broken-for-vehicular-tube-tunnel-is-acclaimed-as.html|url-status=live}}</ref> However, further construction of the Hudson River Tunnel was soon held up due to concerns over its ventilation system.<ref name="nyt-1920-10-10" /> There was also a dispute over whether the [[Government of New York City|New York City government]] should pay for street-widening projects on the New Jersey side.<ref>{{Cite news|url=https://www.nytimes.com/1921/05/02/archives/trying-to-settle-tunnel-dispute-new-jersey-commissioners-want-new.html|title=Trying To Settle Tunnel Dispute|date=May 2, 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/20180505142056/https://www.nytimes.com/1921/05/02/archives/trying-to-settle-tunnel-dispute-new-jersey-commissioners-want-new.html|url-status=live}}</ref> Further delays arose when the New York and New Jersey tunnel commissions could not agree over which agency would award the contract to build the construction and ventilation shafts.<ref>{{Cite news|url=https://www.nytimes.com/1921/07/29/archives/new-hitch-delays-vehicular-tunnel-state-commissions-clash-over.html|title=New Hitch Delays Vehicular Tunnel|date=July 29, 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/20180505142354/https://www.nytimes.com/1921/07/29/archives/new-hitch-delays-vehicular-tunnel-state-commissions-clash-over.html|url-status=live}}</ref>

====Ventilation system====
{{multiple image
| align     = right
| direction = horizontal
| 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]]
}}

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>

==== Tunnel boring ====
[[File:Construction of Holland Tunnel.jpg|thumb|upright=1.1|Construction of Holland Tunnel on November 25, 1922]]
[[File:Holland Tunnel under construction 1923.jpg|thumb|upright=1.1|Construction on the tunnel in 1923]]
The ventilation system and other potential issues had been resolved by December 1921, and officials announced that the tunnel would break ground the following spring.<ref>{{Cite news|url=https://www.nytimes.com/1921/12/30/archives/advertise-for-tube-bids-ground-will-be-broken-for-vehicular-tunnel.html|title=Advertise for Tube Bids|date=December 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/20180505142448/https://www.nytimes.com/1921/12/30/archives/advertise-for-tube-bids-ground-will-be-broken-for-vehicular-tunnel.html|url-status=live}}</ref> Builders initially considered building a trench at the bottom of the [[Hudson River]] and then covering it up, but this was deemed infeasible because of the soft soil that comprised the riverbed, as well as the heavy maritime traffic that used the river.<ref name="nris" />{{rp|11}} Officials started purchasing the properties in the path of the tunnel's approaches, evicting and compensating the tenants "without delay" so that construction could commence promptly.<ref>{{Cite news|url=https://www.nytimes.com/1922/01/08/archives/vehicular-tubes-in-three-years-rapid-transfers-of-1600000-of-real.html|title=Vehicular Tubes in Three Years|date=January 8, 1922|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/20180505143654/https://www.nytimes.com/1922/01/08/archives/vehicular-tubes-in-three-years-rapid-transfers-of-1600000-of-real.html|url-status=live}}</ref> A bid to construct the tubes was advertised, and three firms responded.<ref>{{Cite news|url=https://www.nytimes.com/1922/02/16/archives/19250000-lowest-jersey-tunnel-bid-booth-flinn-ltd-probably-will-get.html|title=$19,250,000 Lowest Jersey Tunnel Bid|date=February 16, 1922|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/20180505144029/https://www.nytimes.com/1922/02/16/archives/19250000-lowest-jersey-tunnel-bid-booth-flinn-ltd-probably-will-get.html|url-status=live}}</ref> On March 29, 1922, the contract to dig the tubes was awarded to the lowest bidder, Booth & Flinn Ltd., for $19.3&nbsp;million.<ref>{{Cite news|url=https://www.nytimes.com/1922/03/29/archives/contract-awarded-for-jersey-tunnel-booth-flinn-ltd-to-construct-the.html|title=Contract Awarded for Jersey Tunnel|date=March 29, 1922|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/20180505134946/https://www.nytimes.com/1922/03/29/archives/contract-awarded-for-jersey-tunnel-booth-flinn-ltd-to-construct-the.html|url-status=live}}</ref> The materials that were necessary to furnish the Hudson River Tunnel had already been purchased, so it was decided to start work immediately.<ref name="nyt-1922-03-31">{{Cite news|url=https://www.nytimes.com/1922/03/31/archives/work-begins-today-on-jersey-tunnel-first-stroke-of-a-pick-to-be.html|title=Work Begins Today on Jersey Tunnel|date=March 31, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=April 9, 2018|archive-url=https://web.archive.org/web/20180409180002/https://www.nytimes.com/1922/03/31/archives/work-begins-today-on-jersey-tunnel-first-stroke-of-a-pick-to-be.html|url-status=live}}</ref> Construction on the bores began two days later as workers broke ground for an air compressor to drive the tubes. The ceremony for the air compressor was held at the corner of [[Canal Street (Manhattan)|Canal Street]] and [[West Side Highway]] on the [[Manhattan]] side.<ref>{{Cite news|url=https://www.nytimes.com/1922/04/01/archives/work-on-vehicular-tunnel-commences-first-ground-for-new-hudson-tube.html|title=Work on Vehicular Tunnel Commences|date=April 1, 1922|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/20180505142401/https://www.nytimes.com/1922/04/01/archives/work-on-vehicular-tunnel-commences-first-ground-for-new-hudson-tube.html|url-status=live}}</ref> The workers who were performing the excavations, who were referred to as "[[sandhog]]s", were to dig each pair of tubes from either bank of the Hudson River, so that the two sides would eventually connect somewhere underneath the riverbed. The tunnel was to be {{convert|9250|ft|m}} long between portals, and the roadway was to descend to a maximum depth of {{convert|93|ft|m}} below mean high water level.<ref name="nyt-1922-03-31" />

The start of construction for the tubes from the [[New Jersey]] side was delayed because the Hudson River Vehicular Tunnel Commission had not yet acquired some of the land for the project.<ref name="nyt-1922-04-03">{{Cite news|url=https://www.nytimes.com/1922/04/23/archives/condemnation-may-end-tunnel-delay-state-commissions-likely-to.html|title=Condemnation May End Tunnel Delay|date=April 23, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110102/https://www.nytimes.com/1922/04/23/archives/condemnation-may-end-tunnel-delay-state-commissions-likely-to.html|url-status=live}}</ref> Although [[Jersey City, New Jersey|Jersey City]] officials had insisted that the Tunnel Commission widen 12th and [[14th Street (Manhattan)|14th]] Streets in Jersey City,<ref>{{Cite news|url=https://www.nytimes.com/1922/04/27/archives/hudson-tunnel-delayed-jersey-city-officials-policy-wiil-result-in.html|title=Hudson Tunnel Delayed|date=April 27, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110034/https://www.nytimes.com/1922/04/27/archives/hudson-tunnel-delayed-jersey-city-officials-policy-wiil-result-in.html|url-status=live}}</ref> these officials were involved in a disagreement over sale prices with the [[Erie Railroad]], which owned some of the land that was to be acquired for the street widening. As a result, work on the Hudson River Tunnel was delayed by one year and could not be completed before 1926 at the earliest.<ref name="nyt-1922-04-03" /> Work on the New Jersey side finally started on May 30, 1922, after [[Jersey City, New Jersey|Jersey City]] officials continued to refuse to cede public land for the construction of the tunnel's plazas. The Jersey City Chamber of Commerce wrote a letter that denounced this action, since the New Jersey Tunnel Commission's members on the Hudson River Tunnel Commission had not been notified of the groundbreaking until they read about it in the following day's newspapers.<ref>{{Cite news|url=https://www.nytimes.com/1922/06/21/archives/tunnel-work-arouses-jersey-city-chamber-commission-told-ground.html|title=Tunnel Work Arouses Jersey City Chamber|date=June 21, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506104018/https://www.nytimes.com/1922/06/21/archives/tunnel-work-arouses-jersey-city-chamber-commission-told-ground.html|url-status=live}}</ref> In mid-June, a state chancellor made permanent an injunction that banned Jersey City officials from trying to preclude construction on the Hudson River Tunnel.<ref>{{Cite news|url=https://www.nytimes.com/1922/07/14/archives/jersey-city-loses-fight-on-tunnel-temporary-injunction-barring-any.html|title=Jersey City Loses Fight On Tunnel|date=July 14, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110109/https://www.nytimes.com/1922/07/14/archives/jersey-city-loses-fight-on-tunnel-temporary-injunction-barring-any.html|url-status=live}}</ref> The Hudson River Tunnel Commission ultimately decided that Jersey City would not have its own groundbreaking celebration due to the city's various efforts at blocking the tunnel's construction.<ref>{{Cite news|url=https://www.nytimes.com/1922/08/23/archives/jersey-fails-to-get-tunnel-celebration-obstructive-tuctics-of.html|title=Jersey Fails To Get Tunnel Celebration|date=August 23, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506175151/https://www.nytimes.com/1922/08/23/archives/jersey-fails-to-get-tunnel-celebration-obstructive-tuctics-of.html|url-status=live}}</ref> However, although Jersey City officials had been primarily accused of delaying construction, officials from both states had wanted the Tunnel Commission to widen the approach streets to the Hudson River Tunnel as part of the construction process.<ref>{{Cite news|url=https://www.nytimes.com/1923/10/24/archives/plaza-the-snag-in-tunnel-project-both-jersey-city-and-new-york.html|title=Plaza the Snag in Tunnel Project|date=October 24, 1923|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/20180506173546/https://www.nytimes.com/1923/10/24/archives/plaza-the-snag-in-tunnel-project-both-jersey-city-and-new-york.html|url-status=live}}</ref>

For the project, six tunnel digging shields were to be delivered.<ref name="nyt-1922-03-31" /> These shields comprised cylinders whose diameters were wider than the tunnel bores, and these cylinders contained steel plates of various thicknesses on the face that was to be driven under the riverbed.<ref name="Howe 1924" /> Four of the shields would dig the Hudson River Tunnel under the river, while the remaining two shields would dig from the Hudson River west bank to the Jersey City portals. They could dig through rock at a rate of {{convert|2.5|ft|m}} per day, or through mud at a daily rate of {{convert|5|to|6|ft|m}}. The air compressors would provide an air pressure of {{convert|20|to|45|psi|kPa}}.<ref>{{Cite news|url=https://www.nytimes.com/1922/10/15/archives/first-shield-set-up-for-vehicular-tunnel-work-of-driving-only.html|title=First Shield Set Up For Vehicular Tunnel|date=October 15, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110038/https://www.nytimes.com/1922/10/15/archives/first-shield-set-up-for-vehicular-tunnel-work-of-driving-only.html|url-status=live}}</ref> The shovels used to dig the tunnel were provided by the [[Marion Power Shovel Company]],<ref>{{cite journal|title=Contractors & Engineers Magazine|journal=Contractors & Engineers Magazine|volume=10|year=1925|page=80}}</ref> while the six digging shields were built by the Merchants Shipbuilding Corporation.<ref>{{Cite news|url=https://www.nytimes.com/1922/04/13/archives/shields-for-new-tunnel-plans-for-six-steel-shells-for-boring-under.html|title=Shields for New Tunnel|date=April 13, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110035/https://www.nytimes.com/1922/04/13/archives/shields-for-new-tunnel-plans-for-six-steel-shells-for-boring-under.html|url-status=live}}</ref> The air compressor was completed in September 1922, and the first shield was fitted into place in the Manhattan side's construction shaft. By this point, the shafts on the New Jersey side were being excavated, and two watertight [[Caisson (engineering)|caissons]] were being constructed.<ref>{{Cite news|url=https://www.nytimes.com/1922/09/12/archives/new-hudson-tube-boring-is-begun-actual-work-on-tunnel-starts-with.html|title=New Hudson Tube Boring Is Begun|date=September 12, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110014/https://www.nytimes.com/1922/09/12/archives/new-hudson-tube-boring-is-begun-actual-work-on-tunnel-starts-with.html|url-status=live}}</ref><ref name="Howe 1924" />

The shield started boring in late October of that year after the steel plates that were necessary for the shield's operation had been delivered.<ref>{{Cite news|url=https://www.nytimes.com/1922/10/27/archives/shield-starts-bore-for-hudson-tunnel-first-ring-weighing-nearly-24.html|title=Shield Starts Bore For Hudson Tunnel|date=October 27, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110031/https://www.nytimes.com/1922/10/27/archives/shield-starts-bore-for-hudson-tunnel-first-ring-weighing-nearly-24.html|url-status=live}}</ref> The first permanent steel-rings lining the tubes were laid a short time afterward.<ref>{{Cite news|url=https://www.nytimes.com/1922/11/12/archives/tunnel-borers-find-thrill-under-river-encounter-strange-deposits-of.html|title=Tunnel Borers Find Thrill Under River|date=November 12, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506110039/https://www.nytimes.com/1922/11/12/archives/tunnel-borers-find-thrill-under-river-encounter-strange-deposits-of.html|url-status=live}}</ref> The caissons were completed and launched into the river in December,<ref>{{Cite news|url=https://www.nytimes.com/1922/12/24/archives/biggest-caisson-to-lie-under-hudson.html|title=Biggest Caisson to Lie Under Hudson|date=December 24, 1922|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506104322/https://www.nytimes.com/1922/12/24/archives/biggest-caisson-to-lie-under-hudson.html|url-status=live}}</ref> and after the caissons were outfitted with the requisite equipment such as [[airlock]]s,<ref name="Howe 1924" /> tugboats dropped the caissons into place in January 1923.<ref>{{Cite news|url=https://www.nytimes.com/1923/01/31/archives/trip-of-big-caisson-stiff-job-for-tugs-bulk-of-1200-tons-towed-from.html|title=Trip Of Big Caisson Stiff Job For Tugs|date=January 31, 1923|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506104133/https://www.nytimes.com/1923/01/31/archives/trip-of-big-caisson-stiff-job-for-tugs-bulk-of-1200-tons-towed-from.html|url-status=live}}</ref> Officials projected that at this rate of progress, the tunnel would be finished within 36 months, by late 1926 or early 1927.<ref>{{Cite news|url=https://www.nytimes.com/1923/01/01/archives/big-hudson-tunnel-ready-in-36-months-preliminary-work-indicates.html|title=Big Hudson Tunnel Ready In 36 Months|date=1923-01-01|work=The New York Times|issn=0362-4331|access-date=May 5, 2018|archive-date=May 6, 2018|archive-url=https://web.archive.org/web/20180506104338/https://www.nytimes.com/1923/01/01/archives/big-hudson-tunnel-ready-in-36-months-preliminary-work-indicates.html|url-status=live}}</ref>

Tunnel construction required the sandhogs to spend large amounts of time in the caisson under high pressure of up to {{convert|47.5|psi|kPa}}, which was thought to be necessary to prevent river water from entering prior to completion of the tubes.<ref name="pmid9444066" /> The caissons were massive metal boxes with varying dimensions, but each contained {{convert|6|ft|m|-thick|adj=mid}} walls.<ref name="Howe 1924" /> Sandhogs entered the tunnel through a series of airlocks, and could only remain inside of the tunnel for a designated time period. On exiting the tunnel, sandhogs had to undergo controlled decompression to avoid [[decompression sickness]] or "the bends", a condition in which nitrogen bubbles form in the blood from rapid decompression.<ref name="pmid9444066">{{cite journal |last=Kindwall |first=Eric P|year=1997|title=Compressed air tunneling and caisson work decompression procedures: development, problems, and solutions|url=http://archive.rubicon-foundation.org/2267|journal=[[Undersea and Hyperbaric Medicine Journal]]|volume=24|issue=4|pages=337–45|pmid=9444066|access-date=March 11, 2009|archive-date=August 11, 2011|archive-url=https://web.archive.org/web/20110811175339/http://archive.rubicon-foundation.org/2267|url-status=dead}}</ref><ref name="Buffalo Courier Express 1927">{{Cite news|url=http://fultonhistory.com/highlighter/highlight-for-xml?altUrl=http%3A%2F%2Ffultonhistory.com%2FNewspapers%252021%2FBuffalo%2520NY%2520Courier%2520Express%2FBuffalo%2520NY%2520Courier%2520Express%25201927%2FBuffalo%2520NY%2520Courier%2520Express%25201927%2520-%25208314.pdf|title=Great Vehicular Tunnel Under Hudson Opens Soon|date=October 30, 1927|work=Buffalo Courier Express|access-date=April 16, 2018|pages=3T|via=[[Fultonhistory.com]]|archive-date=February 25, 2023|archive-url=https://web.archive.org/web/20230225232916/https://fultonhistory.com/Newspapers%2021/Buffalo%20NY%20Courier%20Express/Buffalo%20NY%20Courier%20Express%201927/Buffalo%20NY%20Courier%20Express%201927%20-%208314.pdf|url-status=live}}</ref> The rate of decompression for sandhogs working on the Hudson River Tunnel was described as being "so small as to be negligible".<ref name="nyt-1922-03-02">{{Cite news|url=https://www.nytimes.com/1924/03/02/archives/vehicular-tunnel-work-progressing-engineers-of-hudson-river-project.html|title=Vehicular Tunnel Work Progressing|date=March 2, 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/20180506104130/https://www.nytimes.com/1924/03/02/archives/vehicular-tunnel-work-progressing-engineers-of-hudson-river-project.html|url-status=live}}</ref> Sandhogs underwent such decompressions 756,000 times throughout the course of construction, which resulted in 528 cases of the bends, though none were fatal.<ref>{{Cite book|url=https://books.google.com/books?id=mAP4zZTvdfEC|title=Saga in Steel and Concrete – Norwegian Engineers in America|last=Bjork|first=Kenneth|date=2007|publisher=Read Books|isbn=978-1-40676-829-9|pages=181–190|language=en|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> The tunnel's pressurization caused other problems, including a pressure blowout in April 1924 that flooded the tube.<ref>{{Cite news|url=https://www.nytimes.com/1924/04/04/archives/blowout-floods-vehicular-tube-water-rushes-into-one-section-of-new.html|title=Blow-Out Floods Vehicular Tube|date=April 4, 1924|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054417/https://www.nytimes.com/1924/04/04/archives/blowout-floods-vehicular-tube-water-rushes-into-one-section-of-new.html|url-status=live}}</ref><ref name="Buffalo Courier Express 1927" />

Due to the geology of the Hudson River, the shields digging from the New Jersey side were mostly being driven through mud, and so could be driven at a faster rate than the shields from the New York side, which were being dug through large rock formations. When workers tried to dig through the Manhattan shoreline, they had encountered several weeks of delay due to the existence of an as-yet-unrecorded granite [[Bulkhead (barrier)|bulkhead]] on the shoreline.<ref name="nyt-1923-12-23">{{Cite news|url=https://www.nytimes.com/1923/12/23/archives/first-tunnel-link-is-now-complete-huge-shield-boring-under-hudson.html|title=First Tunnel Link is Now Complete|date=December 23, 1923|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/20180506110104/https://www.nytimes.com/1923/12/23/archives/first-tunnel-link-is-now-complete-huge-shield-boring-under-hudson.html|url-status=live}}</ref> In September 1923, after having proceeded about {{convert|1100|ft|m}} from the Manhattan shoreline, workers encountered a sheet of [[Manhattan schist]] under the riverbed, forcing them to slow shield digging operations from {{convert|12.5|ft/day|m/day}} to less than {{convert|1|ft/day|m/day}}. This outcropping was fed from a stream in Manhattan that emptied into the Hudson River. The sandhogs planned to use small explosive charges to dig through the rock shelf without damaging the shield.<ref>{{Cite news|url=https://www.nytimes.com/1923/09/09/archives/rock-wall-found-under-the-hudson-borers-of-vehicular-tunnel.html|title=Rock Wall Found Under The Hudson|date=September 9, 1923|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/20180506105949/https://www.nytimes.com/1923/09/09/archives/rock-wall-found-under-the-hudson-borers-of-vehicular-tunnel.html|url-status=live}}</ref> By December 1923, about {{convert|4400|ft|m}} of each tube's total length had been excavated, and the first of the shields had passed through the underwater shafts that had been sunk during construction.<ref name="nyt-1923-12-23" /> Due to these unexpected issues, the cost estimate for the tunnel was increased from $28&nbsp;million to $42&nbsp;million in January 1924.<ref>{{Cite news|url=https://www.nytimes.com/1924/01/15/archives/vehicular-tunnel-cost-up-14000000-new-jersey-commission-increases.html|title=Vehicular Tunnel Cost Up $14,000,000|date=January 15, 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/20180506173524/https://www.nytimes.com/1924/01/15/archives/vehicular-tunnel-cost-up-14000000-new-jersey-commission-increases.html|url-status=live}}</ref> By March 1924, all seven of the ventilation shafts had been dug, and three of the four shields that were digging underwater had passed through their respective underwater construction shafts, with the fourth shield nearing its respective shaft.<ref name="nyt-1922-03-02" />

Workers also performed tests to determine whether they could receive radio transmissions while inside the tunnel. They found that they were able to receive transmissions within much of the Hudson River Tunnel.<ref>{{Cite news|url=https://www.nytimes.com/1924/01/05/archives/radio-waves-heard-in-the-jersey-tube-penetrate-water-mud-and-steel.html|title=Radio Waves Heard In The Jersey Tube|date=January 5, 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/20180506104148/https://www.nytimes.com/1924/01/05/archives/radio-waves-heard-in-the-jersey-tube-penetrate-water-mud-and-steel.html|url-status=live}}</ref> However, a New Jersey radio station later found that there was a spot in the middle of the tunnel that had no reception.<ref>{{Cite news|url=https://www.nytimes.com/1927/10/22/archives/radio-music-is-faint-in-vehicular-tunnel-officials-of-woda-find.html|title=Radio Music Is Faint In Vehicular Tunnel|date=October 22, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054309/https://www.nytimes.com/1927/10/22/archives/radio-music-is-faint-in-vehicular-tunnel-officials-of-woda-find.html|url-status=live}}</ref>

The cost of the project increased as work progressed. In July 1923, the New York and New Jersey Vehicular Tunnel Commission had revised plans for the entrance and exit plazas on each side to accommodate an increase in traffic along Canal Street on the Manhattan side. The commission had spent $2.1&nbsp;million to acquire land.<ref name="nyt-1926-02-10">{{Cite news|url=https://www.nytimes.com/1926/02/10/archives/3200000-more-asked-for-tunnel-cost-of-vehicular-tube-now-expected.html|title=$3,200,000 More Asked for Tunnel|date=February 10, 1926|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052718/https://www.nytimes.com/1926/02/10/archives/3200000-more-asked-for-tunnel-cost-of-vehicular-tube-now-expected.html|url-status=live}}</ref> Further redesigns were made in January 1924 due to a change of major components in the tunnel plan, including tunnel diameters and ventilation systems, which had increased the cost by another $14&nbsp;million.<ref name="nyt-1926-02-10" />

==== Nearing completion ====
[[File:Entrance to Holland Tunnel in New Jersey.JPG|thumb|upright=1.1|The [[Jersey City, New Jersey|Jersey City]] entrance to the tunnel in March 2015]]
[[File:Rainy Day (36638025002).jpg|thumb|upright=1.1|Aerial view of [[Lower Manhattan]] with cars entering the Holland Tunnel (foreground) in March 2017]]
The two ends of both tubes were scheduled to be connected to each other at a ceremony on October 29, 1924, in which President [[Calvin Coolidge]] would have remotely set off an explosion to connect the tunnel's two sides.<ref>{{cite web | title=Tubes Under River Will Meet Oct. 29 | website=The New York Times | issn=0362-4331 | date=October 12, 1924 | url=https://www.nytimes.com/1924/10/12/archives/tubes-under-river-will-meet-oct-29-remaining-wall-of-earth-between.html | access-date=May 6, 2018 | archive-date=May 10, 2018 | archive-url=https://web.archive.org/web/20180510052757/https://www.nytimes.com/1924/10/12/archives/tubes-under-river-will-meet-oct-29-remaining-wall-of-earth-between.html | url-status=live }}</ref> However, two days before the ceremony, Holland died of a heart attack at the [[Battle Creek Sanitarium|sanatorium in Battle Creek, Michigan]], aged 41. Individuals cited in ''[[The New York Times]]'' attributed his death to the stress associated with overseeing the tunnel's construction. The ceremony was postponed out of respect for Holland's death.<ref>{{cite news|url=https://www.nytimes.com/1924/10/28/archives/onholinddibsi-altbl-brkdowni-_-chief-engineer-ofhudson-river-tunnel.html|title=C. M. Holland Dies After Breakdown|date=October 28, 1924|newspaper=The New York Times|issn=0362-4331|access-date=May 29, 2010|page=23|archive-date=April 2, 2018|archive-url=https://web.archive.org/web/20180402102228/https://www.nytimes.com/1924/10/28/archives/onholinddibsi-altbl-brkdowni-_-chief-engineer-ofhudson-river-tunnel.html|url-status=live}}</ref>

The tunnel was ultimately holed through on October 29, but it was a nondescript event without any ceremony.<ref name="ASCE" /> On November 12, 1924, the Hudson River Vehicular Tunnel was renamed the Holland Tunnel by the two states' respective tunnel commissions.<ref>{{Cite news|url=https://www.nytimes.com/1924/11/13/archives/submits-a-new-bid-for-ads-in-subway-artemus-ward-inc-proposes.html|title=Submits A New Bid For Ads In Subway|date=November 13, 1924|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052714/https://www.nytimes.com/1924/11/13/archives/submits-a-new-bid-for-ads-in-subway-artemus-ward-inc-proposes.html|url-status=live}}</ref> Holland was succeeded by Milton Harvey Freeman, who died of [[pneumonia]] in March 1925, after several months of overseeing the project.<ref name="New York Sun 1926" /><ref name="nyt-1925-03-26">{{cite news|url=https://www.nytimes.com/1925/03/26/archives/another-engineer-dies-on-big-tunnel-job-mh-freeman-is-victim-of.html|title=Another Engineer Dies on Big Tunnel Job|date=March 26, 1925|newspaper=The New York Times|issn=0362-4331|access-date=May 29, 2010|page=1|archive-date=April 9, 2018|archive-url=https://web.archive.org/web/20180409233529/https://www.nytimes.com/1925/03/26/archives/another-engineer-dies-on-big-tunnel-job-mh-freeman-is-victim-of.html|url-status=live}}</ref> After Freeman's death, the position was occupied by [[Ole Singstad]], who oversaw the tunnel's completion.<ref name="Krebs 1969" /><ref name="New York Sun 1926">{{Cite news|url=http://fultonhistory.com/highlighter/highlight-for-xml?altUrl=http%3A%2F%2Ffultonhistory.com%2FNewspaper%252018%2FNew%2520York%2520NY%2520Sun%2FNew%2520York%2520NY%2520Sun%25201924%2FNew%2520York%2520NY%2520Sun%25201924%2520-%25201502.pdf|title=Smoke Bombs to be Fired in Motor Tunnel|date=February 10, 1926|work=New York Sun|access-date=April 16, 2018|pages=26|via=[[Fultonhistory.com]]}}</ref>

As part of the tunnel project, one block of Watts Street in Manhattan was widened to accommodate traffic heading toward the westbound tube.<ref>{{Cite news|url=https://www.nytimes.com/1926/02/24/archives/fight-plaza-change-in-river-tube-plan-tunnel-commission-asks-board.html|title=Fight Plaza Change In River Tube Plan|date=February 24, 1926|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054402/https://www.nytimes.com/1926/02/24/archives/fight-plaza-change-in-river-tube-plan-tunnel-commission-asks-board.html|url-status=live}}</ref> [[Sixth Avenue (Manhattan)|Sixth Avenue]] was also widened and extended between [[Greenwich Village]] and [[Church Street (Manhattan)|Church Street]]. Ten thousand people were evicted to make way for the Sixth Avenue extension.<ref>{{Cite news|url=https://www.nytimes.com/1926/07/29/archives/10000-must-leave-condemned-houses-citys-order-to-persons-in-path-of.html|title=10,000 Must Leave Condemned Houses|date=July 29, 1926|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510050833/https://www.nytimes.com/1926/07/29/archives/10000-must-leave-condemned-houses-citys-order-to-persons-in-path-of.html|url-status=live}}</ref> The north-south [[Church Street (Manhattan)|Church Street]] was widened and extended southward to [[Church Street and Trinity Place]]; [[West Side Highway]] was expanded and supplemented with an [[West Side Elevated Highway|elevated highway]]; and the west-east Vestry and Laight Streets were also widened.<ref name="nyt-1927-08-21">{{Cite news|url=https://www.nytimes.com/1927/08/21/archives/holland-tube-roadways-involve-a-huge-task-engineering-effort-now.html|title=Holland Tube Roadways Involve A Huge Task|last=Walker|first=Waldo|date=August 21, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=June 21, 2018|archive-url=https://web.archive.org/web/20180621093045/https://www.nytimes.com/1927/08/21/archives/holland-tube-roadways-involve-a-huge-task-engineering-effort-now.html|url-status=live}}</ref> On the New Jersey side, the Holland Tunnel was to connect a new highway (formerly the [[New Jersey Route 25#Route 1 Extension: 1922-1932|Route 1 Extension]]; now [[New Jersey Route 139]]), which extended westward to [[Newark, New Jersey|Newark]].<ref name="nyt-1926-05-30" /> This included a {{convert|2100|ft|m|adj=on}} viaduct, rising {{convert|80|ft|m}} from 12th and 14th Streets, at the bottom of [[The Palisades (Hudson River)|the Palisades]], to the new highway, at the top of the Palisades.<ref name="nyt-1927-08-21" /> The New Jersey highway approach was opened in stages beginning in 1927,<ref>{{Cite news|url=https://www.nytimes.com/1927/06/19/archives/jersey-road-link-will-open-july-4-viaduct-in-jersey-city-which-will.html|title=Jersey Road Link Will Open July 4|date=June 19, 1927|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054422/https://www.nytimes.com/1927/06/19/archives/jersey-road-link-will-open-july-4-viaduct-in-jersey-city-which-will.html|url-status=live}}</ref> and most of that highway was finished in 1930.<ref>{{Cite news|url=https://www.nytimes.com/1930/09/28/archives/new-jersey-opens-new-auto-route.html|title=New Jersey Opens New Auto Route|date=September 28, 1930|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=June 21, 2018|archive-url=https://web.archive.org/web/20180621070058/https://www.nytimes.com/1930/09/28/archives/new-jersey-opens-new-auto-route.html|url-status=live}}</ref>

The construction of the tunnel approach roads on the New Jersey side was delayed for months by [[Erie Railroad]], whose [[Bergen Arches]] right-of-way ran parallel to and directly south of Route 139, in the [[Right-of-way (transportation)|right of way]] of the proposed approach roads. Although the Erie had promised to find another site for its railroad yards, it had refused to respond to the plans that the [[New Jersey State Highway Commission]] had sent them. In March 1925, the Highway Commission decided that construction on the approach roads would begin regardless of Erie's response, and so the land would be taken using [[eminent domain]].<ref>{{Cite news|url=https://www.nytimes.com/1925/03/14/archives/the-erie-delays-tube-jersey-board-avers-highway-commission-says-it.html|title=The Erie Delays Tube, Jersey Board Avers|date=March 14, 1925|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052701/https://www.nytimes.com/1925/03/14/archives/the-erie-delays-tube-jersey-board-avers-highway-commission-says-it.html|url-status=live}}</ref> This led to a legal disagreement between the Erie and the Highway Commission.<ref>{{Cite news|url=https://www.nytimes.com/1925/04/26/archives/railroad-and-state-seek-priority-ruling-court-to-decide-eminent.html|title=Railroad And State Seek Priority Ruling|date=April 26, 1925|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054223/https://www.nytimes.com/1925/04/26/archives/railroad-and-state-seek-priority-ruling-court-to-decide-eminent.html|url-status=live}}</ref> The Erie maintained that it absolutely needed 30 feet of land along 12th Street, while the Highway Commission stated that the most direct approach to the eastbound Holland Tunnel's 12th Street portal should be made using 12th Street. The commission rejected a suggestion that it should use 13th Street, one block north, because it would cost $500,000 more and involve two perpendicular turns.<ref>{{Cite news|url=https://www.nytimes.com/1925/05/07/archives/erie-wont-budge-from-tunnel-site-counsel-says-road-will-fight-to.html|title=Erie Won't Budge From Tunnel Site|date=May 7, 1925|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052827/https://www.nytimes.com/1925/05/07/archives/erie-wont-budge-from-tunnel-site-counsel-says-road-will-fight-to.html|url-status=live}}</ref> In October 1926, one million dollars was allocated to the completion of the Route 139 approach.<ref>{{Cite news|url=https://www.nytimes.com/1926/10/06/archives/1000000-for-tunnel-approach.html|title=$1,000,000 for Tunnel Approach|date=October 6, 1926|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052539/https://www.nytimes.com/1926/10/06/archives/1000000-for-tunnel-approach.html|url-status=live}}</ref>

The contracts for constructing the Holland Tunnel's ventilation systems were awarded in December 1925.<ref>{{Cite news|url=https://www.nytimes.com/1925/12/16/archives/bids-to-ventilate-tunnel-1577000-is-lowest-offer-to-erect-buildings.html|title=Bids To Ventilate Tunnel|date=December 16, 1925|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054419/https://www.nytimes.com/1925/12/16/archives/bids-to-ventilate-tunnel-1577000-is-lowest-offer-to-erect-buildings.html|url-status=live}}</ref> Two months later, the New York-New Jersey Vehicular Tunnel Commission asked for $3.2&nbsp;million more in funding.  The tunnel was now expected to cost $46&nbsp;million, an increase of $17&nbsp;million over what was originally budgeted.<ref name="nyt-1926-02-10" /> The Holland Tunnel was nearly complete: in March 1926, Singstad stated that the tunnel was expected to be opened by the following February.<ref>{{Cite news|url=https://www.nytimes.com/1926/03/10/archives/jersey-tunnel-will-be-ready-next-february-engineer-says.html|title=Jersey Tunnel Will Be Ready Next February, Engineer Says|date=March 10, 1926|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052807/https://www.nytimes.com/1926/03/10/archives/jersey-tunnel-will-be-ready-next-february-engineer-says.html|url-status=live}}</ref> By May 1926, the tubes had been almost completely furnished: the polished-white tile walls were in place, as were the bright lighting systems and the Belgian-block-and-concrete road surfaces.<ref name="nyt-1926-05-30" /> The north tube's tiles were sourced locally by the Sonzogni Brothers of [[Union City, New Jersey]], while the south tube's tiles were sourced in equal amounts from Czechoslovakia and Germany.<ref name="nris" />{{rp|4}} The tiles' surfaces were specially engineered so that they could maintain their coloring even after years of use. The lighting systems used in the Holland Tunnel were designed to allow motorists to adjust to a gradual change in lighting levels just before leaving the tubes.<ref name="New York Sun 1927" />

The ventilation towers were the only major component of the Holland Tunnel that was not completed, but major progress had been made by the end of 1926.<ref name="nyt-1926-11-28">{{Cite news|url=https://www.nytimes.com/1926/11/28/archives/big-river-towers-give-air-to-tube-powerful-machinery-is-being.html|title=Big River Towers Give Air To Tube; Powerful Machinery Is Being Installed on Jersey and Manhattan Shores to Ventilate The Holland Vehicular Tunnel|date=November 28, 1926|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054206/https://www.nytimes.com/1926/11/28/archives/big-river-towers-give-air-to-tube-powerful-machinery-is-being.html|url-status=live}}</ref> Ole Singstad and the two states' tunnel commissions tested the tunnel's ventilation system by releasing gas clouds in one of the tubes in February 1927. Singstad subsequently declared that the ventilation system was well equipped to ventilate the tunnel air.<ref name="nyt-1927-03-16" /> However, the New York Board of Trade and Transportation disagreed, stating that the system would be inadequate if there was a genuine incident within the tunnel. In April 1927, the board had conducted their own tests with two lighted candles, and a cloud of smoke had filled the entire tube before the ventilation system was able to perform a full exhaust.<ref>{{Cite news|url=https://www.nytimes.com/1927/04/14/archives/ventilation-in-tube-called-a-menace-board-of-trade-wants-defects.html|title=Ventilation In Tube Called A Menace|date=April 14, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052619/https://www.nytimes.com/1927/04/14/archives/ventilation-in-tube-called-a-menace-board-of-trade-wants-defects.html|url-status=live}}</ref> The Chief Surgeon of the U.S. Board of Mines supported Singstad's position that the ventilation system could sufficiently filter the tubes' air.<ref>{{Cite news|url=https://www.nytimes.com/1927/04/28/archives/says-vehicular-tube-will-have-ample-air-dr-rr-sayers-of-the-bureau.html|title=Says Vehicular Tube Will Have Ample Air|date=April 28, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054252/https://www.nytimes.com/1927/04/28/archives/says-vehicular-tube-will-have-ample-air-dr-rr-sayers-of-the-bureau.html|url-status=live}}</ref> To affirm the ventilation system's efficacy, in November 1927, the New York and New Jersey tunnel commissions burned a car within the tunnel; the ventilation system dissipated the fire within three and a half minutes.<ref>{{Cite news|url=https://www.nytimes.com/1927/11/04/archives/automobile-burned-in-new-tube-as-test-holland-tunnel-experiment.html|title=Automobile Burned In New Tube As Test|date=November 4, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052747/https://www.nytimes.com/1927/11/04/archives/automobile-burned-in-new-tube-as-test-holland-tunnel-experiment.html|url-status=live}}</ref>

The governors of New York and New Jersey took ceremonial rides through the tunnel in August 1926, meeting at the tunnel's midpoint.<ref>{{Cite news|url=https://www.nytimes.com/1926/08/22/archives/smith-and-moore-meet-in-tunnel-governors-shake-hands-as-they-reach.html|title=Smith And Moore Meet In Tunnel|date=August 22, 1926|work=The New York Times|issn=0362-4331|access-date=May 8, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510115231/https://www.nytimes.com/1926/08/22/archives/smith-and-moore-meet-in-tunnel-governors-shake-hands-as-they-reach.html|url-status=live}}</ref> The first unofficial drive through the entirety of the Holland Tunnel was undertaken by a group of British businessmen a year later, in August 1927.<ref>{{Cite news|url=https://www.nytimes.com/1927/08/26/archives/british-merchants-ride-under-hudson-delegation-is-first-unofficial.html|title=British Merchants Ride Under Hudson|date=August 26, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054215/https://www.nytimes.com/1927/08/26/archives/british-merchants-ride-under-hudson-delegation-is-first-unofficial.html|url-status=live}}</ref> The next month, a group from the Buffalo and Niagara Frontier Port Authority Survey Commission also visited the tunnel.<ref>{{Cite news|url=https://www.nytimes.com/1927/09/29/archives/inspects-vehicular-tube-buffalo-commission-also-studies-site-for.html|title=Inspects Vehicular Tube|date=September 29, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510054258/https://www.nytimes.com/1927/09/29/archives/inspects-vehicular-tube-buffalo-commission-also-studies-site-for.html|url-status=live}}</ref> In October, a delegation of representatives from [[Detroit|Detroit, Michigan]], and [[Windsor, Ontario]], toured the nearly complete Holland Tunnel to get ideas for the then-proposed [[Detroit–Windsor Tunnel]].<ref>{{Cite news|url=http://fultonhistory.com/highlighter/highlight-for-xml?altUrl=http%3A%2F%2Ffultonhistory.com%2FNewspaper%252018%2FNew%2520York%2520NY%2520Sun%2FNew%2520York%2520NY%2520Sun%25201927%2FNew%2520York%2520NY%2520%25201927%2520-%25204669.pdf|title=Detroiters See Hudson Tunnel|date=October 14, 1927|work=New York Sun|access-date=April 16, 2018|pages=59|via=[[Fultonhistory.com]]}}</ref><ref>{{Cite news|url=https://www.nytimes.com/1927/10/15/archives/detroit-engineers-visit-holland-tube-come-with-windsor-ontario.html|title=Detroit Engineers Visit Holland Tube|date=October 15, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052805/https://www.nytimes.com/1927/10/15/archives/detroit-engineers-visit-holland-tube-come-with-windsor-ontario.html|url-status=live}}</ref> A reporter for ''The New York Times'' was able to make a test drive through the tunnel, noting that "there is no sudden pressure of wind upon the ear-drums" and that it would reduce the duration of crossing the Hudson River by between 15 and 22 minutes.<ref name="nyt-1927-10-02" /> Three hundred police officers were trained in advance of the Holland Tunnel's opening,<ref>{{Cite news|url=https://www.nytimes.com/1927/05/16/archives/300-traffic-police-for-holland-tube-patrol-for-vehicular-tunnel.html|title=300 Traffic Police For Holland Tube|date=May 16, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510052645/https://www.nytimes.com/1927/05/16/archives/300-traffic-police-for-holland-tube-patrol-for-vehicular-tunnel.html|url-status=live}}</ref> and bus companies started receiving franchises to operate buses through the tunnel.<ref>{{Cite news|url=https://www.nytimes.com/1927/07/06/archives/holland-tunnel-bus-lines-nevins-company-gets-franchises-to-operate.html|title=Holland Tunnel Bus Lines|date=July 6, 1927|work=The New York Times|issn=0362-4331|access-date=May 9, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510050904/https://www.nytimes.com/1927/07/06/archives/holland-tunnel-bus-lines-nevins-company-gets-franchises-to-operate.html|url-status=live}}</ref>