Editing Diamond interchange (section)

=== Dumbbell ===
{{For|the at-grade intersection design analogous to dumbbell and dogbone interchanges|Bowtie (road)}}
[[File:Holt Road Dogbone.png|thumb|right|A dumbbell interchange along [[Ontario Highway 401]] in [[Clarington|Clarington, Ontario]], Canada. This one features a loop ramp.<br />{{coord|43|53|3|N|78|43|20|W}}]]
The ramp intersections may also be configured as a pair of [[roundabout]]s<ref name="FHWA 9"/> to create a type of diamond interchange often called a '''dumbbell interchange'''{{cn|date=September 2024}} (due to its aerial resemblance to a [[dumbbell]]), and sometimes called a '''double roundabout interchange'''.<ref>[[Federal Highway Administration]] (FHWA): [https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/mutcd2009r1r2edition.pdf Manual on Uniform Traffic Control Devices] ([[MUTCD]]), Edition 2009, Revision 2, May 2012], ''Figure 3C-14. Example of Markings for a Diamond Interchange with Two Circular-Shaped, Roundabout Ramp Terminals'', p.412 (PDF p.452)</ref><ref name="FHWA 9"/> Because roundabouts can generally handle traffic with fewer approach lanes than other intersection types, interchange construction costs can be reduced by eliminating the need for a wider bridge. This configuration allows other roads to form approach legs to the roundabouts and also allows easy [[U-turn]]s.<ref name="ATTAP">{{cite web |publisher= [[University of Maryland, College Park]] / [[Maryland State Highway Administration]] |url= http://attap.umd.edu/UAID_gsus.php?UAIDType=16&iFeature=5 |work= An Applied Technology and Traffic Analysis Program: Unconventional Arterial Intersection Design |title= Double Roundabout Interchange: Design and Operations |year= 2011 |access-date= February 25, 2013 |archive-url= https://web.archive.org/web/20131224095709/http://attap.umd.edu/UAID_gsus.php?UAIDType=16&iFeature=5 |archive-date= December 24, 2013 |url-status= dead }}</ref>

This type of interchange is common in the [[United Kingdom]] and [[Republic of Ireland|Ireland]], and is becoming increasingly common in the [[United States]]. Examples of dumbbell interchanges in the United States are located on [[Interstate 35]] in [[Medford, Minnesota|Medford]], Minnesota, on [[Interstate 87 (New York)|Interstate 87]] in [[Malta, New York|Malta]], New York, on [[Interstate 17]] at Happy Valley Road north of [[Phoenix, Arizona|Phoenix]], Arizona, and on [[Interstate 80]] at [[California State Route 89]] (exit 185) in [[Truckee, California|Truckee]], California. An example in Canada is found on the [[British Columbia Highway 17|Pat Bay Highway]] in [[North Saanich, British Columbia|North Saanich]], British Columbia, near [[Victoria International Airport]].

One or both roundabouts in the dumbbell interchange may also contain side lanes to increase the capacity. A good example of such a [[Roundabout#Turbo roundabouts|"turbo" dumbbell]] interchange, which was formerly a half cloverleaf, can be seen in [[Jülich]], Germany at {{coord|50.914055|N|6.323368|E}}.

There are interchanges similar to dumbbells in which the ramps do not meet the roundabouts at intersections; these more closely resemble bowtie intersections. One such interchange exists at the junction between the [[Ruta Interbalnearia]] and Route 35 North near [[La Floresta, Uruguay|La Floresta]], Uruguay ({{coord|34.7495|S|55.6775|W|dim:300}}).