View source for Four Level Interchange

{{Short description|Stack interchange in Los Angeles}}
{{Use mdy dates|date=January 2025}}
{{Infobox road junction
|country=USA
|name=Four Level Interchange
|image=Four Level Interchange.jpg
|image_caption= Four Level Interchange of Arroyo Seco Parkway, Harbor Freeway, Santa Ana Freeway and Hollywood Freeway, looking northeast in January 1999
|maint=[[California Department of Transportation]]
|location=[[Los Angeles]], [[California]]
|coord={{coord|34|3|45|N|118|14|55|W|display=inline,title}}
|roads={{Plainlist|
*{{Jct|country=USA|SR|110|state=CA|name1=[[Arroyo Seco Parkway]] / Harbor Freeway}}
*{{Jct|country=USA|US|101|state=CA|name1=[[Hollywood Freeway]] / [[Santa Ana Freeway]]}}
}}
|type= Four-level [[stack interchange]]
|const=1949
|opened=1953
|height=
|other_names=Bill Keene Memorial Interchange
}}

The '''Four Level Interchange''' (officially the '''Bill Keene Memorial Interchange''') is the first [[stack interchange]] in the world.<ref>[http://cache.search.yahoo-ht2.akadns.net/search/cache?ei=UTF-8&p=Four+Level+interchange&fr=slv8-msgr&u=members.cox.net/mkpl/interchange/interchange.html&w=four+level+leveling+levels+interchange&d=IAEcZZzfQ9Jj&icp=1&.intl=us Four Level interchange-Los Angeles-Orange County Frwys]{{Dead link|date=December 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Completed in 1949 and fully opened in 1953 at the northern edge of [[Downtown Los Angeles]], [[California]], [[United States]], it connects [[U.S. Route 101 in California|U.S. Route 101]] ([[Hollywood Freeway]] and [[Santa Ana Freeway]]) to [[Interstate 110 and State Route 110 (California)|State Route 110]] ([[Harbor Freeway]] and [[Arroyo Seco Parkway]]). In 2006, the interchange was officially renamed in the memory of Los Angeles traffic and weather reporter [[Bill Keene]].

==Description==
The highway is a [[stack interchange]] that connects [[U.S. Route 101 in California|U.S. Route 101]] to [[California State Route 110|State Route 110]]. All movements are possible in this interchange between US 101, which crosses over SR 110, but not necessarily with surrounding roads, like [[Sunset Boulevard]], which crosses SR 110 just northeast of the interchange. The interchange is located at Exit 3 of US 101 and Exit 24A of SR 110.

The four freeway segments ("paths" of travel) from the Four Level Interchange are:
* {{Jct|state=CA|US|101|dir1=north|name1=[[Hollywood Freeway]]|city1=Ventura}}
* {{Jct|state=CA|US|101|dir1=south|name1=[[Santa Ana Freeway]]|to2=yes|I|5|dir2=south|I|10|dir3=east|SR|60|dir4=east}}
* {{Jct|state=CA|SR|110|dir1=north|name1=[[Arroyo Seco Parkway]]|city1=Pasadena}}
* {{Jct|state=CA|SR|110|dir1=south|name1=[[Harbor Freeway]]|to2=yes|I|110|dir2=south|city1=San Pedro}}

==History==
While the highway oriented east–west at this intersection has consistently been numbered US&nbsp;101, the numerical designation of road oriented north–south at this interchange has changed over the years. Originally designated [[U.S. Route 66 (California)|U.S. Route 66]] and [[U.S. Route 6 (California)|U.S. Route 6]] and later signed as State Route 11, all of these designations were eventually removed from the intersection and replaced with the current designation of Route 110.

The four-level reinforced concrete structure was designed by a team of engineers and built by the James I. Barnes Construction Company. Although it was finished in 1949, it was not put into full use until the freeways it served were completed and opened on 22 September 1953.<ref>{{cite web |url=https://www.laconservancy.org/locations/four-level-interchange |title=Four-Level Interchange |last1= |first1= |last2= |first2= |date=  |publisher=LA Conservancy |access-date=August 2, 2021}}</ref><ref>{{cite web|title=On This Day In Automotive History Motoring|website=365 Days Of Motoring|url=https://365daysofmotoring.com/the-first-four-level-or-stack-interchange-in-the-world-opened-in-los-angeles-california-at-the-intersection-of-the-harbor-hollywood-pasadena-and-santa-ana-freeways-where-32-la/}}</ref>

In July 2006, the freeway interchange was officially named in honor of [[Bill Keene]], former [[KNX (AM)|KNX]] and [[KCBS-TV|KNXT]] traffic and weather reporter, although the new name is rarely used. Keene referred to the interchange as "The Stacks" and the "4-H Interchange". During the 1960s, [[Dick Whittinghill]] on [[radio station]] [[KMPC]] sometimes called it the [[four-letter word|Four Letter]] Interchange.<ref>[http://www.floodgap.com/roadgap/110/ Floodgap-Arroyo Seco Parkway]
</ref>

The interchange was constructed as a stack interchange because surrounding buildings and terrain made construction of a [[cloverleaf interchange]] impractical. The construction of the interchange displaced over 4,000 people from their homes and cost $5.5 million (${{Format price|{{Inflation|US-GDP|5500000|1952}}}} in {{Inflation-year|US-GDP}}) - making it the most expensive half-mile of highway ever built at the time.<ref>{{cite web |url=http://www.history.com/this-day-in-history/the-famous-four-level-opens-in-los-angeles |title=The famous "four-level" opens in Los Angeles |last1= |first1= |last2= |first2= |date= |website=History.com |publisher=History |access-date=February 21, 2015}}</ref>

The mainline traffic of US 101 is at the top of the interchange, above the ramps, a rarity in stack interchanges. Other examples of similar configurations would later be constructed, including on the [[M25 motorway|M25]] interchange with [[M23 motorway|M23]] passing above the ramps (south of [[London]]), the junction of [[Interstate 695 (Maryland)|I-695]] and [[Interstate 70 in Maryland|I-70]] in [[Baltimore]], and the [[Interstate 805]]–[[Interstate 8]] interchange in [[San Diego]].

Its distinctive architecture has long made it a symbol of Los Angeles' post–[[World War II]] development, and it appears on numerous [[postcard]]s from the 1950s and 1960s.<ref>{{cite web|url=http://www.dot.ca.gov/dist11/photogallery/fourlevel.htm|archive-url=https://web.archive.org/web/20030919231143/http://www.dot.ca.gov/dist11/photogallery/fourlevel.htm|url-status=dead|archive-date=September 19, 2003|title=California: District 11: 1954 Four Level Interchange|work=ca.gov}}</ref>

==See also==
*{{Portal-inline|California Roads}}
*[[Dosan Ahn Chang Ho Memorial Interchange]], the counterpart at the southern edge of Downtown Los Angeles
*[[List of bridges documented by the Historic American Engineering Record in California]]

==References==
{{Reflist}}

==External links==
{{Commons category|Bill Keene Memorial Interchange}}
*{{Cite web |url=http://www.kcet.org/updaily/socal_focus/history/la-as-subject/navigating-the-stack-the-four-level-turns-58.html |title=L.A.'s Famous Four-Level Freeway Interchange, 'The Stack,' Turns 58 |website=kcet.org|date=22 September 2011 }}
*{{HAER |survey=CA-266 |id=ca2787 |title=Four Level Interchange, Los Angeles, Los Angeles County, CA |photos=2 |cap=1}}

[[Category:Southern California freeways]]
[[Category:Road interchanges in California]]
[[Category:Buildings and structures on U.S. Route 66]]
[[Category:U.S. Route 101]]
[[Category:Interstate 10]]
[[Category:Transportation buildings and structures in Los Angeles]]
[[Category:Historic American Engineering Record in California]]