Interstate 270 (Colorado)
Map of the Denver area with I-270 highlighted in red
|Maintained by CDOT|
|Length:||7.107 mi (11.438 km)|
|Existed:||1965 – present|
|West end:||I-25 / US 36 in Welby|
| I-76 in North Washington
US 6 / US 85 / SH 2 at Commerce City
|East end:||I-70 / US 36 at Denver|
Interstate 270 (I-270) is a 7-mile-long (11 km) highway in the northeastern part of the Denver–Aurora Metropolitan Area in the U.S. state of Colorado. It overlaps U.S. Highway 36 (US 36) for its entire length. The western terminus of I-270 is at the interchange with I-25 and US 36. It heads eastward to an interchange with I-76, where the mileposts reset because of a previous freeway extension. The freeway heads southeast and comes to meet Vasquez Boulevard, where it enters Commerce City. The road crosses Quebec Street before ending at I-70.
Ground was broken on the first segment of I-270 in 1965, and the freeway was completed three years later, stretching from I-70 to Vasquez Boulevard. The road was then extended to I-76 two years later. The section between I-25 and I-76 was completed in 1999. Since completion, this section has undergone much construction to renew bridges over Clear Creek and Washington Street. Because the western end of I-270 is close to the junction of I-25 and I-76, some traffic movements to I-25 can only be made by using I-76.
I-270 begins at an interchange with I-25 in Welby, and is concurrent with US 36. The speed limit through the first section is 45 mph (72 km/h). The freeway heads southeastward for about one mile (1.6 km), crossing over Washington Street and State Highway 224 (SH 224), but access is not provided to either road. Mileposts along I-270 reset to zero at the I-76 interchange because it was the original western end of the Interstate. Since the I-76 interchange is close to both I-270's western end and to the I-25 / I-76 interchanges, some movements in the interchange are missing. Eastbound I-270 traffic cannot access westbound I-76, nor can westbound I-76 traffic access eastbound I-270. However, traffic on I-25 can access both westbound I-76 and eastbound I-270, thus completing the missing movements. The three interchanges work together by eliminating bottlenecks caused by redundant interchanges.
Beyond the I-76 interchange, the speed limit increases to 55 mph (89 km/h). The freeway heads southeast and comes to a westbound exit and eastbound entrance with York Street, and crosses the South Platte River  into a commercial area in Adams County. I-270 enters the city of Commerce City, running roughly parallel with the nearby Sand Creek and crossing over SH 265 without an exit. Continuing through the city, the route comes to a cloverleaf interchange with Vasquez Boulevard, which carries US 85, SH 2, and US 6. The freeway heads eastward into Denver, where it has an exit at SH 35, a short highway which continues northward along Quebec Street for one mile (1.6 km). Quebec Street provides access for traffic heading to westbound I-70. The route ends shortly thereafter when it merges into I-70.
The freeway is maintained by the Colorado Department of Transportation (CDOT), who is responsible for maintaining and constructing transportation infrastructure in Colorado, including highways. As part of this role, CDOT periodically conducts surveys on their highways to measure traffic volume. This is expressed in terms of average annual daily traffic (AADT), which is a measure of traffic volume for any average day of the year. In 2009, CDOT calculated that as few as 56,500 vehicles used I-270 daily east of its western terminus at I-25, and as many as 89,600 vehicles used I-270 daily southeast of York Street in Commerce City. As part of the Interstate Highway System, the entire route is listed on the National Highway System, a system of roads that are important to the nation's economy, defense, and mobility.
I-270 was constructed in several phases, beginning with a section from I-70 to Vasquez Boulevard. Following this section was another part of the freeway from Vasquez Boulevard west to I-76, and finally a section from US 36 to I-76. This last segment has undergone much more construction, including new bridges and ramps at interchanges.
Construction on I-270 began in 1965. The first portion cost about $2.7 million. It opened in 1968, connecting I-70 to Vasquez Boulevard. Two years later, another two-mile (3.2 km) segment connected the portion already in service to I-80S. I-80S became I-76 in 1976. Construction began on the section between I-76 and I-25 in April 1993 and was finished in September 1999, costing $11.4 million. The mileposts were already established when construction took place, so the route was not assigned new mileposts. Completion of this portion largely decreased traffic problems in the area.
The bridges along westbound I-270 over Washington Street were replaced and finished in the late 1990s, costing $12 million. By the end of 1998, the bridges over Clear Creek near the I-76 interchange were completed. In February 2000, a connection between westbound I-270 and westbound US 36 was completed, as was access between I-76 westbound and I-270 westbound.  The eastbound section between US 36 and I-76, including new bridges over Washington Street and Clear Creek, was completed in March 2002 and totaled $8.5 million. Three years later, a flyover ramp was constructed connecting I-25 southbound to I-270 eastbound. However, access between I-270 eastbound and I-76 westbound still does not exist.
As part of the Strategic Transportation Project, CDOT plans to improve the interchange between I-76 and I-270 by adding a flyover ramp from I-270 eastbound to I-76 eastbound in a $15 million project. CDOT intends to install automatic systems for spraying de-icing fluids installed in the pavement on this ramp as well. However, this project is only a proposal and could be changed depending on funding. CDOT also aims to widen the freeway from four up to six lanes between I-76 and I-70 by 2025.
|Adams||Welby||0.000||0.000||0|| US 36 west (Denver–Boulder Turnpike) – Boulder
I-25 north – Fort Collins
|US 36 is the continuation beyond I-25; no exit to southbound I-25 and no entrance from northbound I-25|
|1||I-76 to I-25 south – Grand Junction, Fort Morgan, Denver||No eastbound exit from I-270 to westbound I-76; no eastbound entrance to I-270 from westbound I-76; mileposts reset at this interchange, which was the original start of the freeway|
|0.385||0.620||—||York Street||Westbound exit and eastbound entrance|
|Commerce City||2.358||3.795||2||US 85 / SH 2 (Vasquez Boulevard)||Signed as exits 2A (north) and 2B (south)|
|City and County of Denver||4.569||7.353||4||SH 35 to I-70 west – Denver|
|5.378||8.655||5||Central Park Boulevard||Eastbound exit only; westbound exit via I-70|
|5.986||9.634||—||I-70 east / US 36 – Limon|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi
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- Colorado Department of Transportation. "About CDOT". Retrieved February 18, 2011.
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- "Table 3: Interstate Routes in Each of the 50 States, District of Columbia, and Puerto Rico". FHWA Route Log and Finder List. Federal Highway Administration. October 31, 2002. Retrieved February 18, 2011.
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- "I-270 Link to US 36 Hailed as 1.1 Headache-Free Miles.". Rocky Mountain News (Denver). August 16, 2003.
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- Colorado Department of Transportation. "Structure List for I-270". Retrieved February 2, 2011.
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- Leib, Jeffrey (October 23, 2008). "De-icer System to Spray Ramps Automatically". The Denver Post. Retrieved February 1, 2011.
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- Leib, Jeffrey (December 18, 2008). "Construction Projects to Hit Metro-Area Roads". The Denver Post. Retrieved February 1, 2011.
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