Editing Pontoon bridge (section)

===United States===

In the United States, [[combat engineer]]s were responsible for bridge deployment and construction. These were formed principally into [[Engineer Combat Battalion]]s, which had a wide range of duties beyond bridging, and specialized units, including [[Engineer Light Ponton Company|Light Ponton Bridge Companies]], [[Pontoon bridge#Heavy Ponton Bridge Battalion|Heavy Ponton Bridge Battalion]]s, and [[Pontoon bridge#Engineer Treadway Bridge Company|Engineer Treadway Bridge Companies]]; any of these could be organically attached to infantry units or directly at the [[Army division|divisional]], [[Army corps|corps]], or [[army]] level.{{citation needed|date=August 2015}}

American engineers built three types of floating bridges: M1938 infantry footbridges, M1938 ponton bridges, and M1940 treadway bridges, with numerous subvariants of each. These were designed to carry troops and vehicles of varying weight, using either an inflatable pneumatic ponton or a solid aluminum-alloy ponton bridge.<ref name=anderson>{{cite web|last1=Anderson|first1=Rich|title=U.S. Army in World War II Engineers and Logistics|url=http://www.militaryhistoryonline.com/wwii/usarmy/engineers.aspx|access-date=6 December 2014|archive-date=11 December 2014|archive-url=https://web.archive.org/web/20141211130945/http://www.militaryhistoryonline.com/wwii/usarmy/engineers.aspx|url-status=live}}</ref> Both types of bridges were supported by pontons (known today as "pontoons") fitted with a deck built of balk, which were square, hollow aluminum beams.<ref name=trainmanual>{{cite web |url=https://rdl.train.army.mil/catalog-ws/view/100.ATSC/B64B6D4D-844B-4D85-A636-8FA752D870F2-1274308527938/5-210/ch5.htm |work=Military Float Bridging Equipment |title=M4T6 Floating Bridges And Rafts |edition=Training Circular No. 5-210 |date=27 December 1988 |access-date=8 December 2014 |archive-url=https://web.archive.org/web/20150427130129/https://rdl.train.army.mil/catalog-ws/view/100.ATSC/B64B6D4D-844B-4D85-A636-8FA752D870F2-1274308527938/5-210/ch5.htm |archive-date=27 April 2015 |url-status=dead }}</ref>

;American Light Ponton Bridge Company
{{Main|Engineer Light Ponton Company}}
An Engineer Light Ponton Company consisted of three platoons: two bridge platoons, each equipped with one unit of M3 pneumatic bridge, and a lightly equipped platoon which had one unit of footbridge and equipment for ferrying.<ref name=fm55>{{Cite web |url=http://www.ibiblio.org/hyperwar/USA/ref/FM/PDFs/FM5-5.PDF |title=Engineer Field Manual FM 5-5 |access-date=2014-12-18 |archive-date=2015-09-24 |archive-url=https://web.archive.org/web/20150924075752/http://www.ibiblio.org/hyperwar/USA/ref/FM/PDFs/FM5-5.PDF |url-status=live }}</ref> The bridge platoons were equipped with the M3 pneumatic bridge, which was constructed of heavy inflatable pneumatic floats and could handle up to {{convert|10|ST}}; this was suitable for all normal infantry division loads without reinforcement, greater with.

;American Heavy Ponton Bridge Battalion
A Heavy Ponton Bridge Battalion was provided with equipage required to provide stream crossing for heavy military vehicles that could not be supported by a light ponton bridge. The Battalion had two lettered companies of two bridge platoons each. Each platoon was equipped with one unit of heavy ponton equipage. The battalion was an organic unit of army and higher echelons. The M1940 could carry up to {{convert|25|ST}}.<ref name=fm55/><ref name=eng300/> The M1 Treadway Bridge could support up to {{convert|20|ST}}. The roadway, made of steel, could carry up to {{convert|50|ST}}, while the center section made of {{convert|4|in}} thick plywood could carry up to {{convert|30|ST}}. The wider, heavier tanks used the outside steel treadway while the narrower, lighter jeeps and trucks drove across the bridge with one wheel in the steel treadway and the other on the plywood.<ref>{{cite book|last1=Beck|first1=Alfred M.|title=The Corps of Engineers-The Technical Services: The War Against Germany (United States Army in World War II)|date=Dec 31, 1985|publisher=Center for Military History|isbn=978-0160019388|page=293}}</ref><ref>{{cite web|last1=Roe|first1=Pat|title=General O. P Smith Interview|url=http://www.chosinreservoir.com/smithinterview.htm|website=Chosin Reservoir Korea November - December 1950|access-date=2015-04-05|archive-date=2015-03-12|archive-url=https://web.archive.org/web/20150312195633/http://www.chosinreservoir.com/smithinterview.htm|url-status=live}}</ref>

;American Engineer Treadway Bridge Company
An Engineer Treadway Bridge Company consisted of company headquarters and two bridge platoons. It was an organic unit of the armored force, and normally was attached to an Armored Engineer Battalion. Each bridge platoon transported one unit of steel treadway bridge equipage for construction of ferries and bridges in river-crossing operations of the armored division.<ref name=fm55/> Stream-crossing equipment included utility powerboats, pneumatic floats, and two units of steel treadway bridge equipment, each of which allowed the engineers to build a floating bridge about {{convert|540|ft}} in length.<ref name=fm55/>
;Materials and equipment

;; Pneumatic ponton

The [[United States Army Corps of Engineers]] designed a self-contained bridge transportation and erection system. The [[Brockway Motor Company|Brockway]] model B666 {{convert|6|ST}} 6x6 truck chassis (also built under license by Corbitt and [[White Motor Company|White]]) was used to transport both the bridge's steel and rubber components. A single Brockway truck could carry material for {{convert|30|ft}} of bridge, including two pontons, two steel saddles that were attached to the pontons, and four treadway sections.<ref name=obrine>{{cite journal|last1=O'Brine|first1=Jack|title=Combat Engineers Take a River in Their Stride|journal=Popular Mechanics|date=December 1943|url=https://books.google.com/books?id=fScDAAAAMBAJ&q=popular+science+1943+there%27s+one+thrill+no+soldier&pg=PA86|access-date=18 December 2014|archive-date=6 July 2022|archive-url=https://web.archive.org/web/20220706064846/https://books.google.com/books?id=fScDAAAAMBAJ&q=popular+science+1943+there%27s+one+thrill+no+soldier&pg=PA86|url-status=live}}</ref> Each treadway was {{convert|15|ft}} long with high guardrails on either side of the {{convert|2|ft}} wide track.<ref name=obrine/>

The truck was mounted with a {{convert|4|ST}} hydraulic crane that was used to unload the {{convert|45|in|cm}} wide steel treadways. A custom designed twin boom arm was attached to rear of the truck bed and helped unroll and place the heavy inflatable rubber pontoons upon which the bridge was laid. The {{convert|220|in|cm}} wheelbase chassis included a {{convert|25000|lb}} front winch and extra-large air-brake tanks that also served to inflate the rubber pontoons before they were placed in the water.<ref>{{cite web|title=The Right Way, a History of Brockway Trucks|url=http://www.coachbuilt.com/bui/b/brockway/brockway_2.htm|access-date=8 December 2014|archive-date=19 December 2017|archive-url=https://web.archive.org/web/20171219231738/http://www.coachbuilt.com/bui/b/brockway/brockway_2.htm|url-status=live}}</ref>

A pneumatic float was made of rubberized fabric separated by bulkheads into 12 airtight compartments and inflated with air.<ref>[https://books.google.com/books?id=Z7wtAgAAQBAJ&pg=PA138 U.S. Army Explosives and Demolitions Handbook] {{Webarchive|url=https://web.archive.org/web/20200820035906/https://books.google.com/books?id=Z7wtAgAAQBAJ&pg=PA138 |date=2020-08-20 }}  Department of the Army</ref> The pneumatic float consisted of an outer perimeter tube, a floor, and a removable center tube. The {{convert|18|ST}} capacity float was {{convert|8|ft|3|in}} wide, {{convert|33|ft}} long, {{convert|2|ft|9|in}} deep.<ref>{{cite book|last1=Wong|first1=John B.|title=Battle Bridges: Combat River Crossings: World War II|date=2004|publisher=Trafford|location=Victoria, B.C.|isbn=9781412020671|access-date=8 December 2014|url=https://books.google.com/books?id=9wAKvcxsI-gC&pg=PA14|archive-date=24 December 2016|archive-url=https://web.archive.org/web/20161224144815/https://books.google.com/books?id=9wAKvcxsI-gC&pg=PA14|url-status=live}}</ref>

;; Solid ponton

Solid aluminum-alloy pontons were used in place of pneumatic floats to support heavier bridges and loads.<ref name=trainmanual/> They were also pressed into service for lighter loads as needed.

;; Treadway

A treadway bridge was a multi-section, prefabricated floating steel bridge supported by pontoons carrying two metal tracks (or "tread ways") forming a roadway. Depending on its weight class, the treadway bridge was supported either by heavy inflatable pneumatic pontons or by aluminum-alloy half-pontons. The aluminum half-pontons were {{convert|29|ft|7|in}} long overall, {{convert|6|ft|11|in}} wide at the gunwales, and {{convert|3|ft|4|in}} deep except at the bow where the gunwale was raised. The gunwales were {{convert|6| ft| 8|in}} center-to-center. At {{convert|6|in}} [[Freeboard (nautical)|freeboard]], the half-ponton has a displacement of {{convert|26500|lb}}. The sides and bow of the half-ponton were gradually sloped, permitting two or more to be nested for transporting or storing.<ref>{{cite book |url=https://books.google.com/books?id=e5wbXXjIzDMC&pg=PA13 |title=Bridge Floating M4 |publisher=United States Army |access-date=December 7, 2014 |year=1954 |archive-date=August 19, 2020 |archive-url=https://web.archive.org/web/20200819042034/https://books.google.com/books?id=e5wbXXjIzDMC&pg=PA13 |url-status=live }}</ref>

A treadway bridge could be built of floating spans or fixed spans.<ref>{{cite web|title=treadway bridge|url=http://www.merriam-webster.com/dictionary/treadway%20bridge|website=Merriam Webster|access-date=6 December 2014|archive-date=10 December 2014|archive-url=https://web.archive.org/web/20141210221528/http://www.merriam-webster.com/dictionary/treadway%20bridge|url-status=live}}</ref> An M2 treadway bridge was designed to carry artillery, heavy duty trucks, and medium tanks up to {{convert|40|ST}}.<ref name=eng300>{{cite web|title=What They Did: Building Bridges and Roads|url=http://www.300thcombatengineersinwwii.com/bridges.html|website=WW II 300th Combat Engineers|access-date=6 December 2014|archive-date=10 December 2014|archive-url=https://web.archive.org/web/20141210031343/http://www.300thcombatengineersinwwii.com/bridges.html|url-status=usurped}}</ref> This could be of any length, and was what was used over major river obstacles such as the Rhine and Moselle. Doctrine stated that it would take {{frac|5|1|2}} hours to place a 362-foot section of M2 treadway during daylight and {{frac|7|1|2}} hours at night. Pergrin says that in practise 50&nbsp;ft/hour of treadway construction was expected, which is a little slower than the speed specified by doctrine.<ref name=firefury>{{cite web|title=Battlefront WWII Some Facts about Bridging operations|url=http://www.fireandfury.com/extra/bridging.shtml|access-date=28 March 2015|archive-date=2 April 2015|archive-url=https://web.archive.org/web/20150402122801/http://www.fireandfury.com/extra/bridging.shtml|url-status=live}}</ref>

By 1943, combat engineers faced the need for bridges to bear weights of 35 tons or more. To increase weight bearing capacity, they used bigger floats to add buoyancy. This overcame the capacity limitation, but the larger floats were both more difficult to transport to the crossing site and requiring more and larger trucks in the divisional and corps trains.<ref>{{cite web |url=http://xbradtc.com/2012/01/17/treadway-bridge/ |title=Treadway Bridge |access-date=December 7, 2014 |archive-date=December 10, 2014 |archive-url=https://web.archive.org/web/20141210070543/http://xbradtc.com/2012/01/17/treadway-bridge/ |url-status=live }}</ref>