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		<id>https://www.designingbuildings.co.uk/w/index.php?action=history&amp;feed=atom&amp;title=Gateway_Arch</id>
		<title>Gateway Arch - Revision history</title>
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		<updated>2026-04-13T07:53:33Z</updated>
		<subtitle>Revision history for this page on the wiki</subtitle>
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	<entry>
		<id>https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=181405&amp;oldid=prev</id>
		<title>Designing Buildings at 07:19, 10 November 2020</title>
		<link rel="alternate" type="text/html" href="https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=181405&amp;oldid=prev"/>
				<updated>2020-11-10T07:19:01Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;
&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
		&lt;tr valign='top'&gt;
		&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;← Older revision&lt;/td&gt;
		&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 07:19, 10 November 2020&lt;/td&gt;
		&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 50:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 50:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;* Wembley Stadium.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;* Wembley Stadium.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[Category:&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;Projects_and_case_studies&lt;/del&gt;]] [[Category:DCN_Project_Knowledge]]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[Category:&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;DCN_Commentary&lt;/ins&gt;]] [[Category:DCN_Project_Knowledge&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;]] [[Category:Projects_and_case_studies&lt;/ins&gt;]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Designing Buildings</name></author>	</entry>

	<entry>
		<id>https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=156429&amp;oldid=prev</id>
		<title>92.98.145.156 at 12:07, 15 March 2020</title>
		<link rel="alternate" type="text/html" href="https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=156429&amp;oldid=prev"/>
				<updated>2020-03-15T12:07:21Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;
&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
		&lt;tr valign='top'&gt;
		&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;← Older revision&lt;/td&gt;
		&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 12:07, 15 March 2020&lt;/td&gt;
		&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 15:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 15:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The arch spans 192 m (630 ft) between the outer faces of its triangular legs. Each leg is an equilateral triangle, narrowing from 16 m (54 ft) per side at the bases to 5.2 m (17 ft) at the top. Complex mathematical equations were required to ensure the arch design would work, and the base of each leg at ground level had an engineering tolerance of just 0.4 mm (1/64 inch) to ensure they would meet at the top.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The arch spans 192 m (630 ft) between the outer faces of its triangular legs. Each leg is an equilateral triangle, narrowing from 16 m (54 ft) per side at the bases to 5.2 m (17 ft) at the top. Complex mathematical equations were required to ensure the arch design would work, and the base of each leg at ground level had an engineering tolerance of just 0.4 mm (1/64 inch) to ensure they would meet at the top.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each leg consists of a stainless steel skin covering two carbon-steel walls with reinforced concrete sandwiched between them. This continues until 91 m (300 ft), at which point carbon steel stiffeners are used instead of concrete. These inner and outer stressed-skins join to form a composite structure which carries the self &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;wieght &lt;/del&gt;and wind loads to the ground.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each leg consists of a stainless steel skin covering two carbon-steel walls with reinforced concrete sandwiched between them. This continues until 91 m (300 ft), at which point carbon steel stiffeners are used instead of concrete. These inner and outer stressed-skins join to form a composite structure which carries the self &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;weight &lt;/ins&gt;and wind loads to the ground.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each leg is embedded in concrete foundations 13 m (44 ft) thick and 18 m (60 ft) deep. The arch is earthquake-resistant and designed to sway up to 46 cm (18 inches) in either direction, while withstanding winds of up to 150 miles per hour.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each leg is embedded in concrete foundations 13 m (44 ft) thick and 18 m (60 ft) deep. The arch is earthquake-resistant and designed to sway up to 46 cm (18 inches) in either direction, while withstanding winds of up to 150 miles per hour.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 25:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 25:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction was postponed during World War II, and it wasn’t until 1959 that ground was first broken. The foundations were laid in 1961, and the arch construction itself began in 1963 as the first steel triangle for the south leg was moved into place.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction was postponed during World War II, and it wasn’t until 1959 that ground was first broken. The foundations were laid in 1961, and the arch construction itself began in 1963 as the first steel triangle for the south leg was moved into place.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The steel triangles, narrowing as they &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;spiraled &lt;/del&gt;to the top, were raised into place using a group of cranes and derricks. Once in place, each section was filled with concrete and prestressed with 252 tension bars. As a means of keeping the partially-completed legs steady, a scissors truss was placed between them at 160 m (530 ft). This was later removed as the derricks were dismantled.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The steel triangles, narrowing as they &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;spiralled &lt;/ins&gt;to the top, were raised into place using a group of cranes and derricks. Once in place, each section was filled with concrete and prestressed with 252 tension bars. As a means of keeping the partially-completed legs steady, a scissors truss was placed between them at 160 m (530 ft). This was later removed as the derricks were dismantled.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction progress was delayed by a combination of funding issues, safety checks and legal disputes. Civil rights activists brought work to a stand-still as strikes were held in protest against the fact that African-American workers, who were being discriminated against, were working on the project.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction progress was delayed by a combination of funding issues, safety checks and legal disputes. Civil rights activists brought work to a stand-still as strikes were held in protest against the fact that African-American workers, who were being discriminated against, were working on the project.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 50:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 50:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;* Wembley Stadium.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;* Wembley Stadium.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[Category:Projects_and_case_studies]]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[Category:Projects_and_case_studies&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;]] [[Category:DCN_Project_Knowledge&lt;/ins&gt;]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>[IP address hidden]</name></author>	</entry>

	<entry>
		<id>https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=68953&amp;oldid=prev</id>
		<title>Designing Buildings at 16:00, 2 February 2017</title>
		<link rel="alternate" type="text/html" href="https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=68953&amp;oldid=prev"/>
				<updated>2017-02-02T16:00:43Z</updated>
		
		<summary type="html">&lt;p&gt;&lt;/p&gt;
&lt;table style=&quot;background-color: white; color:black;&quot;&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
			&lt;col class='diff-marker' /&gt;
			&lt;col class='diff-content' /&gt;
		&lt;tr valign='top'&gt;
		&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;← Older revision&lt;/td&gt;
		&lt;td colspan='2' style=&quot;background-color: white; color:black;&quot;&gt;Revision as of 16:00, 2 February 2017&lt;/td&gt;
		&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[File:Gatewayarch.jpg]]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;File:Gatewayarch.jpg|link=&lt;/ins&gt;File:Gatewayarch.jpg]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;= Introduction =&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;= Introduction =&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 5:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 5:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The Gateway Arch is a structural expressionist monument located on the west bank of the Mississippi River in St. Louis, Missouri. It was built as a monument to the westward expansion of the United States. At 192 m (630 ft) in height, it is the world’s tallest arch, and the tallest man-made monument in the Western Hemisphere.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The Gateway Arch is a structural expressionist monument located on the west bank of the Mississippi River in St. Louis, Missouri. It was built as a monument to the westward expansion of the United States. At 192 m (630 ft) in height, it is the world’s tallest arch, and the tallest man-made monument in the Western Hemisphere.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The idea &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;of such a monument &lt;/del&gt;was conceived as part of the Jefferson National Expansion Memorial (JNEM), &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;which was &lt;/del&gt;created in 1935. A nationwide design competition was held in 1947/48 and Ero Saarinen’s arch &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;concept &lt;/del&gt;was chosen as the winner.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The idea was conceived as part of the Jefferson National Expansion Memorial (JNEM), created in 1935. A nationwide design competition was held in 1947/48 and Ero Saarinen’s arch was chosen as the winner. Since its completion in 1965, it has become a popular tourist attraction and a defining symbol of the city of St. Louis.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&amp;#160;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Since its completion in 1965, it has become a popular tourist attraction and a defining symbol of the city of St. Louis.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;= Design =&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;= Design =&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[File:Gatewayarch2.jpg]]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;File:Gatewayarch2.jpg|link=&lt;/ins&gt;File:Gatewayarch2.jpg]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Eero Saarinen conceived of the monument as being clad in stainless steel and built in the form of an inverted, weighted catenary arch, a shape such as would be formed by a heavy chain hanging freely between two supports.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Eero Saarinen conceived of the monument as being clad in stainless steel and built in the form of an inverted, weighted catenary arch, a shape such as would be formed by a heavy chain hanging freely between two supports.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The arch spans 192 m (630 ft) between the outer faces of its triangular legs &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;at ground level&lt;/del&gt;. Each leg is an equilateral triangle, narrowing from 16 m (54 ft) per side at the bases to 5.2 m (17 ft) &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;per side &lt;/del&gt;at the top. Complex mathematical equations were required to ensure the arch design would work &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;in practice. The &lt;/del&gt;base of each leg at ground level had &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;to have &lt;/del&gt;an engineering tolerance of 0.4 mm (1/64 inch) &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;or the two legs would fail &lt;/del&gt;to meet at the top.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The arch spans 192 m (630 ft) between the outer faces of its triangular legs. Each leg is an equilateral triangle, narrowing from 16 m (54 ft) per side at the bases to 5.2 m (17 ft) at the top. Complex mathematical equations were required to ensure the arch design would work&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;, and the &lt;/ins&gt;base of each leg at ground level had an engineering tolerance of &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;just &lt;/ins&gt;0.4 mm (1/64 inch) to &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;ensure they would &lt;/ins&gt;meet at the top.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;wall &lt;/del&gt;consists of a stainless steel skin covering two carbon-steel walls with reinforced concrete sandwiched between them. This continues until 91 m (300 ft), at which point carbon steel stiffeners are used instead of concrete. These inner and outer stressed-skins join to form a composite structure which carries the &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;gravity &lt;/del&gt;and wind loads to the ground&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;, gives it sufficient strength and permanence&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;leg &lt;/ins&gt;consists of a stainless steel skin covering two carbon-steel walls with reinforced concrete sandwiched between them. This continues until 91 m (300 ft), at which point carbon steel stiffeners are used instead of concrete. These inner and outer stressed-skins join to form a composite structure which carries the &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;self wieght &lt;/ins&gt;and wind loads to the ground.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each leg is embedded in concrete foundations 13 m (44 ft) thick and 18 m (60 ft) deep. The arch is earthquake-resistant and designed to sway up to 46 cm (18 inches) in either direction, while withstanding winds of up to 150 miles per hour.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Each leg is embedded in concrete foundations 13 m (44 ft) thick and 18 m (60 ft) deep. The arch is earthquake-resistant and designed to sway up to 46 cm (18 inches) in either direction, while withstanding winds of up to 150 miles per hour.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The arch is hollow and accommodates a tram system that carries visitors from the lobby to an observation deck at the top. Operating at the rate of 340 ft per minute, the ride takes 10 minutes for the full trip. The observation platform is 65 x 7 ft, and fitted with plate-glass windows that provide views &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;in &lt;/del&gt;east and west &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;directions&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The arch is hollow and accommodates a tram system that carries visitors from the lobby to an observation deck at the top. Operating at the rate of 340 ft per minute, the ride takes 10 minutes for the full trip. The observation platform is 65 x 7 ft, and fitted with plate-glass windows that provide views &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;to the &lt;/ins&gt;east and west.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;= Construction =&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;= Construction =&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;on the arch &lt;/del&gt;was &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;halted due to &lt;/del&gt;World War II, and it wasn’t until 1959 that ground was first broken. The foundations were laid in 1961, and the arch construction itself began in 1963 as the first steel triangle &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;on &lt;/del&gt;the south leg was moved into place.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction was &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;postponed during &lt;/ins&gt;World War II, and it wasn’t until 1959 that ground was first broken. The foundations were laid in 1961, and the arch construction itself began in 1963 as the first steel triangle &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;for &lt;/ins&gt;the south leg was moved into place.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The steel triangles, narrowing as they spiraled to the top, were raised into place using a group of cranes and derricks. Once in place, each section was filled with concrete and prestressed with 252 tension bars. As a means of keeping the partially-completed legs steady, a scissors truss was placed between them at 160 m (530 ft). This was later removed as the derricks were dismantled.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;The steel triangles, narrowing as they spiraled to the top, were raised into place using a group of cranes and derricks. Once in place, each section was filled with concrete and prestressed with 252 tension bars. As a means of keeping the partially-completed legs steady, a scissors truss was placed between them at 160 m (530 ft). This was later removed as the derricks were dismantled.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction progress was &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;often &lt;/del&gt;delayed by a combination of funding issues, safety checks and legal disputes. Civil rights activists &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;often &lt;/del&gt;brought work to a stand-still as strikes were held in protest against the fact that African-American workers, who were being discriminated against, were working on the project.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Construction progress was delayed by a combination of funding issues, safety checks and legal disputes. Civil rights activists brought work to a stand-still as strikes were held in protest against the fact that African-American workers, who were being discriminated against, were working on the project.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[File:Gatewayarch1.jpg]]&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;[[&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;File:Gatewayarch1.jpg|link=&lt;/ins&gt;File:Gatewayarch1.jpg]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;minus;&lt;/td&gt;&lt;td style=&quot;background: #ffa; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;On October 28 1965, the arch was finally topped out. The keystone was a 2.4 m (8 ft) long triangular section. To mitigate against thermal expansion, which had constricted the gap at the top by 13 cm (5 inches), fire hoses were used to spray water to cool the surface &lt;del class=&quot;diffchange diffchange-inline&quot;&gt;down &lt;/del&gt;and help it contract. When the keystone was in place, a hydraulic jack was used to pry the legs apart 1.8 m (6 ft), with the final section being inserted to secure the arch.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td style=&quot;background: #cfc; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;On October 28 1965, the arch was finally topped out. The keystone was a 2.4 m (8 ft) long triangular section. To mitigate against thermal expansion, which had constricted the gap at the top by 13 cm (5 inches), fire hoses were used to spray water to cool the surface and help it contract. When the keystone was in place, a hydraulic jack was used to pry the legs apart 1.8 m (6 ft), with the final section being inserted to secure the arch.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Having cost $13 million (equivalent to $190 m in 2015), the arch opened to the public in June 1967.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td style=&quot;background: #eee; color:black; font-size: smaller;&quot;&gt;&lt;div&gt;Having cost $13 million (equivalent to $190 m in 2015), the arch opened to the public in June 1967.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Designing Buildings</name></author>	</entry>

	<entry>
		<id>https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=68921&amp;oldid=prev</id>
		<title>Editor: Created page with &quot;File:Gatewayarch.jpg  = Introduction =  The Gateway Arch is a structural expressionist monument located on the west bank of the Mississippi River in St. Louis, Missouri. It w...&quot;</title>
		<link rel="alternate" type="text/html" href="https://www.designingbuildings.co.uk/w/index.php?title=Gateway_Arch&amp;diff=68921&amp;oldid=prev"/>
				<updated>2017-02-02T15:25:09Z</updated>
		
		<summary type="html">&lt;p&gt;Created page with &amp;quot;&lt;a href=&quot;/wiki/File:Gatewayarch.jpg&quot; title=&quot;File:Gatewayarch.jpg&quot;&gt;File:Gatewayarch.jpg&lt;/a&gt;  = Introduction =  The Gateway Arch is a structural expressionist monument located on the west bank of the Mississippi River in St. Louis, Missouri. It w...&amp;quot;&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;[[File:Gatewayarch.jpg]]&lt;br /&gt;
&lt;br /&gt;
= Introduction =&lt;br /&gt;
&lt;br /&gt;
The Gateway Arch is a structural expressionist monument located on the west bank of the Mississippi River in St. Louis, Missouri. It was built as a monument to the westward expansion of the United States. At 192 m (630 ft) in height, it is the world’s tallest arch, and the tallest man-made monument in the Western Hemisphere.&lt;br /&gt;
&lt;br /&gt;
The idea of such a monument was conceived as part of the Jefferson National Expansion Memorial (JNEM), which was created in 1935. A nationwide design competition was held in 1947/48 and Ero Saarinen’s arch concept was chosen as the winner.&lt;br /&gt;
&lt;br /&gt;
Since its completion in 1965, it has become a popular tourist attraction and a defining symbol of the city of St. Louis.&lt;br /&gt;
&lt;br /&gt;
= Design =&lt;br /&gt;
&lt;br /&gt;
[[File:Gatewayarch2.jpg]]&lt;br /&gt;
&lt;br /&gt;
Eero Saarinen conceived of the monument as being clad in stainless steel and built in the form of an inverted, weighted catenary arch, a shape such as would be formed by a heavy chain hanging freely between two supports.&lt;br /&gt;
&lt;br /&gt;
The arch spans 192 m (630 ft) between the outer faces of its triangular legs at ground level. Each leg is an equilateral triangle, narrowing from 16 m (54 ft) per side at the bases to 5.2 m (17 ft) per side at the top. Complex mathematical equations were required to ensure the arch design would work in practice. The base of each leg at ground level had to have an engineering tolerance of 0.4 mm (1/64 inch) or the two legs would fail to meet at the top.&lt;br /&gt;
&lt;br /&gt;
Each wall consists of a stainless steel skin covering two carbon-steel walls with reinforced concrete sandwiched between them. This continues until 91 m (300 ft), at which point carbon steel stiffeners are used instead of concrete. These inner and outer stressed-skins join to form a composite structure which carries the gravity and wind loads to the ground, gives it sufficient strength and permanence.&lt;br /&gt;
&lt;br /&gt;
Each leg is embedded in concrete foundations 13 m (44 ft) thick and 18 m (60 ft) deep. The arch is earthquake-resistant and designed to sway up to 46 cm (18 inches) in either direction, while withstanding winds of up to 150 miles per hour.&lt;br /&gt;
&lt;br /&gt;
The arch is hollow and accommodates a tram system that carries visitors from the lobby to an observation deck at the top. Operating at the rate of 340 ft per minute, the ride takes 10 minutes for the full trip. The observation platform is 65 x 7 ft, and fitted with plate-glass windows that provide views in east and west directions.&lt;br /&gt;
&lt;br /&gt;
= Construction =&lt;br /&gt;
&lt;br /&gt;
Construction on the arch was halted due to World War II, and it wasn’t until 1959 that ground was first broken. The foundations were laid in 1961, and the arch construction itself began in 1963 as the first steel triangle on the south leg was moved into place.&lt;br /&gt;
&lt;br /&gt;
The steel triangles, narrowing as they spiraled to the top, were raised into place using a group of cranes and derricks. Once in place, each section was filled with concrete and prestressed with 252 tension bars. As a means of keeping the partially-completed legs steady, a scissors truss was placed between them at 160 m (530 ft). This was later removed as the derricks were dismantled.&lt;br /&gt;
&lt;br /&gt;
Construction progress was often delayed by a combination of funding issues, safety checks and legal disputes. Civil rights activists often brought work to a stand-still as strikes were held in protest against the fact that African-American workers, who were being discriminated against, were working on the project.&lt;br /&gt;
&lt;br /&gt;
[[File:Gatewayarch1.jpg]]&lt;br /&gt;
&lt;br /&gt;
On October 28 1965, the arch was finally topped out. The keystone was a 2.4 m (8 ft) long triangular section. To mitigate against thermal expansion, which had constricted the gap at the top by 13 cm (5 inches), fire hoses were used to spray water to cool the surface down and help it contract. When the keystone was in place, a hydraulic jack was used to pry the legs apart 1.8 m (6 ft), with the final section being inserted to secure the arch.&lt;br /&gt;
&lt;br /&gt;
Having cost $13 million (equivalent to $190 m in 2015), the arch opened to the public in June 1967.&lt;br /&gt;
&lt;br /&gt;
= Find out more =&lt;br /&gt;
&lt;br /&gt;
=== Related articles on Designing Buildings Wiki ===&lt;br /&gt;
&lt;br /&gt;
* 7 Engineering Wonders of the World.&lt;br /&gt;
* Arches.&lt;br /&gt;
* Brandenburg Gate.&lt;br /&gt;
* Building of the week series.&lt;br /&gt;
* CN Tower.&lt;br /&gt;
* Optimal arch bridge.&lt;br /&gt;
* Space Needle.&lt;br /&gt;
* Stainless steel.&lt;br /&gt;
* Structural engineer.&lt;br /&gt;
* Wembley Stadium.&lt;br /&gt;
&lt;br /&gt;
[[Category:Projects_and_case_studies]]&lt;/div&gt;</summary>
		<author><name>Editor</name></author>	</entry>

	</feed>