Colorado Highways:
Highway-Related Trivia Items

Longest & Shortest Highways

Longest SH Highways • SH 14 - 236.9 mi • SH 71 - 232.9 mi		Shortest SH Highways • SH 110, Silverton - 0.14 mi • SH 100, Vilas - 0.41 mi
Longest US Highways (Implied Mileage) • US 40 - 486.9 mi • US 50 - 467.5 mi • US 160 - 467.2 mi • US 6 - 467.2 mi		Longest US Highways (Signed Mileage) • US 160 - 467.2 mi (no gaps; overlap with I-25 is signed) • US 50 - 441.4 mi (gap Utah border to Grand Junction) • US 40 - 403.8 mi (gaps Empire to Golden and Aurora to Limon) • US 385 - 317.6 mi
Shortest US Highway • US 400 - 14.8 mi

Determining the longest US Highway in Colorado is not a cut-and-dried thing. The problem in Colorado is that nearly every US Highway at some point has a gap because it becomes unsigned, usually where it has an overlap with an Interstate. For example, if you're eastbound on US 40 through Aurora approaching I-70 at Exit 289, signage for US 40 simply disappears at the interchange. There's no indication of where US 40 goes from there. (You head east on I-70 and US 40 starts up again at Exit 359 in Limon). So, when adding up the mileage for US Highways in Colorado, there are two ways to do it: One is by taking the total mileage across the state, even the "implied" mileage where a US Highway has an unsigned overlap with an Interstate, and the other way is to discount the implied mileage and count only where the US Highway is actively signed. US 160 is longest going by signed mileage, while US 40 is longest with implied mileage.Thanks to Dale Sanderson and "John N" for prompting me to do these calculations.

Colfax Avenue

Urban legend has it that Colfax Avenue in metro Denver -- US 40 from Golden through Denver to east Aurora -- is the longest street in the U.S. at 27 miles. Wrong! I've found a handful that are 10 miles longer, including El Camino Real in south metro San Francisco, Telegraph Road in west metro Detroit, and Sepulveda Boulevard in west metro Los Angeles. I've also heard Colfax referred to as the longest "commercial street" in the country, but that's such an ambiguous phrase there's no way to confirm that. "America's longest Main Street" has also been used, but that depends on your definition of Main Street.

Busiest & Loneliest Stretches of Highway

VPD is vehicles per day. The number is from CDOT's 2008 compiled traffic data, which reports AADT for sections of highway in the state. AADT is Annual Average Daily Traffic, a way of determining the average daily number of vehicles on a roadway, either through actual measurement or statistical analysis.

Busiest Sections of Highway in Colorado • I-25 south of I-70, Denver - 254,000 VPD • Busiest Off of I-25: I-70 east of I-270, Denver - 183,000 VPD		Busiest Sections of Highway That Aren't Freeway • Santa Fe Dr. (US 85) north of Mississippi Ave., Denver - 83,000 VPD • Busiest Off of Santa Fe Dr.: Parker Rd (SH 83) north of Quincy Ave, Aurora - 75,300 VPD
Loneliest Sections of State Highway • South end of SH 101, Bent County - 70 VPD • West end of SH 300, Lake County - 70 VPD • SH 40 northwest of Agate - 90 VPD • SH 116 at the Kansas border - 110 VPD		Loneliest Sections of Freeway • I-76 east of Sedgwick - 5800 VPD • I-76 east of Crook - 6200 VPD • I-70 at the Utah border - 6600 VPD

Tunnels on the State Highway System

Interchanges

Spuis. Here a SPUI, there a SPUI, everywhere a SPUI! OK, what the heck is a SPUI? (pronounced "spooey"). It's a Single Point Urban Interchange, and is a special kind of interchange layout that minimizes the area required. It does this by taking the traditional diamond interchange and pinching the ramps together to form a single intersection, rather than the two intersections required with the diamond. As a result left turns can be done at the same time for oncoming directions allowing three signal phases at two intersections to be replaced with three phases at a single intersection. An important element of SPUIs is whether the cross road, and thus the intersection, is above or below the freeway. If the cross road is above the freeway, this adds greatly to the cost, because a huge bridge structure is needed to suspend the intersection above the freeway. In Colorado, there are SPUIs at:

• I-25/US 50/SH 47, Pueblo - intersection below freeway
• I-25/Garden of The Gods Road, Colorado Springs - intersection below freeway
• I-25/University Boulevard, Denver - intersection below freeway
  
• US 85/Belleview Avenue (SH 88), Littleton - intersection below
  
• US 85/Evans Avenue, Denver - intersection above
  
• SH 470/Morrison Road (SH 8), Morrison - intersection below freeway
• Austin Bluffs Pkwy/Union Blvd, Colorado Springs - intersection below
• Academy Blvd/Woodmen Rd, Colorado Springs - intersection above
  

Another unusual interchange is at I-225/Alameda Avenue in Aurora. It's like a SPUI-diamond hybrid, where the two intersections of a traditional diamond have been combined into one, but instead of the intersection being over or under the freeway, it's off to the side. This was done by having the two ramps on the southbound side of I-225 use flyovers to cross over to the east side of I-225. Thus there's just a single intersection on Alameda on the the east side of I-225.

Cloverleaves. Boy, they loved cloverleaf interchanges in the 1950s and 1960s. They put them in all over the place. Unfortunately many of those cloverleaves are now woefully substandard, given the traffic volumes of today. Between the weavings, sharp ramps and low entrance speeds they have fallen out of favor. Colorado still has some, but not nearly the number it used to:

• Current full cloverleaves in Colorado:
• US 6/SH 121 (Wadsworth Blvd), Lakewood
• I-270/US 6-85/SH 2 (Vasquez Blvd), Commerce City
  
• US 285/SH 470, Morrison
  
• E-470/Pe�a Blvd, Denver. Has C-D roads SB and EB. The newest cloverleaf, it was built in 1998.
  
• 3/4 cloverleaves that used to be full cloverleafs:
• I-25/SH 14, Fort Collins. The SE loop was removed ~2002.
• BL 70/US 40-287/SH 88 (Colfax Ave/Federal Blvd), Denver. The NE loop was removed ~2003.
• 3/4 cloverleaves:
• US 6/SH 391 (Kipling St), Lakewood. It has never had a NE loop.
• Other interchanges that used to be full cloverleaves:
• I-25/North Academy Blvd, Colorado Springs. NE and SW loops removed in 1998.
• I-25/North Entrance Air Force Academy, El Paso County. The NW loop was removed ~2004. Remaining loops were removed in October 2013.
  
• I-25/SH 2 (Colorado Blvd), Denver. NW and SE loops were removed decades ago, then the NE loop was removed in 2003 as part of T-REX.
• I-25/University Blvd, Denver. Converted to SPUI as part of T-REX in 2003.
• I-25/US 6 (6th Ave), Denver. NW and SE loops converted to flyovers in 1989.
• I-25/Speer Blvd, Denver. NW and SW loops removed in 2007.
• I-25/US 34, Loveland. NE and SW loops removed in summer 2010. Slated to be converted to a stack interchange in a future reconstruction project.
  
• I-76/SH 71, Brush. Converted to diamond in 2013.
  
• I-76/US 6/Spur 34, Brush. SE and NW loops removed in 2001. Slated to be converted to a diamond in a future reconstruction project.
  

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Page created 6 August 2003
Last updated 26 October 2013