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Drivers to start navigating new Cimarron/I-25 'SPUI' in late June

       Editor's note: A single-point urban interchange (SPUI) will become operational in late June as a major milestone in the $113-million Cimarron/I-25 project that started in May 2015 and is due for overall completion by December. The following article about the SPUI design was provided by the public relations arm of the Colorado Department of Transportation and edited for publication in the Westside Pioneer.

       A single-point urban interchange (SPUI) was first proposed in the U.S. at two different freeway interchange sites in the 1970s. Today, there are
A graphic shows how traffic will move at the Cimarron/I-25 interchange after the final single-point urban interchange (SPUI) configuration opens in late June. According to state transportation officials, its design should move traffic more efficiently than before.
Courtesy of Colorado Department of Transportation
more than 300 SPUIs in the U.S. and others can be found in Australia, Canada, Greece and Germany.
       In Colorado Springs, working SPUI designs can be seen at the interchanges of Union/Austin Bluffs and at Garden of the Gods/I-25.
       A SPUI helps move large volumes of traffic through limited amounts of space safely and efficiently. These interchanges are a great way to maximize vehicle flow where streams of traffic merge or separate.
       In a SPUI, the arterial and ramp entrances/exits are controlled by a single traffic signal, and the freeway ramps are pushed outward to achieve free-flowing angles. (For reference, see the graphic for the new Cimarron/I-25 interchange
The SPUI graphic (displayed higher up in this article) can be compared with the aerial view here (looking northwest from above the Drake Power Plant) of the former ramp alignments at Cimarron/I-25.
Courtesy of Colorado Department of Transportation
on the upper part of this page. That graphic, in turn, can be compared with the original interchange layout in 1960, as seen in the pre-project aerial photo at left.)
       In 2012, to meet traffic demand in the year 2035, the Environmental Assessment for Highway 24 west of I-25 recommended building the new Cimarron/I-25 interchange as a SPUI.
       The interchange's pre-SPUI design - approved but unfunded as part of the 2005-2007 COSMIX I-25 widening project - had called for a single three-phase, signalized intersection handling all ramp traffic on Cimarron underneath I-25.
       Advantages of the SPUI are:
       Beneficial in urban areas because it can be constructed in limited rights- of-way.
       Reduces signal phases.
       Left-turn paths are flatter and can be made at higher speeds, thus increasing traffic flow and intersection capacity.
       Prior to implementing the final configuration at Cimarron/I-25, overnight closures will take place mid- to late-June for paving and striping operations. Project eAlerts will be issued as reminders prior to these closures, including designated detour routes.
       Watch for detour signs to direct you, adhere to posted speed limits and avoid distractions. For updated project information, visit https://www.codot.gov/projects/i25cimarronDB, or call 719-302-6781.

From a press release
(Posted 6/15/17; Transportation: Cimarron/I-25)

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