Interstate 225

Interstate 225
I-225 highlighted in red
Route information
Auxiliary route of I-25
Maintained by CDOT
Length	11.959 mi[1] (19.246 km)
Existed	1976[2]–present
Major junctions
South end	I-25 / US 87 in Denver
Major intersections	I-70 BL / US 40 / US 287 in Aurora
North end	I-70 / US 36 in Aurora and Denver
Location
Counties	Denver, Arapahoe, Adams
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future Colorado State Highways Interstate US State Scenic ← SH 224 → SH 227

Interstate 225 (I-225) is an 11.959-mile (19.246 km) connector spur route of I-25 in Colorado. It is the only auxiliary route of I-25, and one of two auxiliary Interstate highways in the state of Colorado. I-225 traverses Aurora and small portions of Denver and Greenwood Village. It runs north from I-25 in the Denver Tech Center to I-70 north of Aurora. It interchanges with State Highway 83 (SH 83), SH 30 and Interstate 70 Business (I-70 Bus.)/U.S. Route 40 (US 40)/US 287, known locally as Colfax Avenue. Construction on the freeway began in 1964 at the I-70 interchange and continued progressively through many years, proceeding south through Aurora until final completion in 1976 with the final link between Yosemite Street and I-25.

The freeway is maintained by the Colorado Department of Transportation (CDOT), who is responsible for maintaining and constructing transportation infrastructure across Colorado.^[3]

Route description[]

I-225 is the only active Colorado Interstate that never runs concurrent with another highway in its entire length. The southern end of I-225 begins at an interchange with I-25, as a typical four-lane Interstate with a 65-mile-per-hour (105 km/h) limit. The road heads northeastward through southern Denver,^[4] and, after having exits with DTC Boulevard and Yosemite Street in Greenwood Village,^[5] the road becomes six lanes with an auxiliary lane in each direction, traversing the Denver–Greenwood Village city limits. With Cherry Creek State Park and Cherry Creek Reservoir on its eastside, the highway interchanges with SH 83 at the northern boundary of the park. Following the exit at SH 83, the freeway enters Aurora,^[6] where it turns northward, maintaining six throughlanes and auxiliary lanes at each exit, a 65-mile-per-hour (105 km/h) speed limit to its northern terminus at I-70,^[7] and has upgraded exits at Iliff Avenue, Mississippi Avenue, Alameda Avenue, and 6th Avenue (also signed as SH 30).^[8] After crossing Sand Creek, the freeway interchanges with Colfax Avenue (also signed as US 40, US 287, and I-70 Bus.), and then with 17th Place (serving the Anschutz Medical Campus).^[8] After the exit, I-225 enters Adams County, continuing through the city of Aurora. The route then crosses a railroad and continues north, where it interchanges with I-70.^[9][1] The northbound ramp to westbound I-70 reenters Denver, and the eastbound I-70 to southbound I-225 ramp originates in Denver but enters Aurora as it passes under westbound I-70 to southbound I-225 ramp.^[6]

History[]

1955 map showing planned Interstate Highways around Denver

I-225 was originally proposed by CDOT to be numbered as I-25E on April 3, 1958, based upon the Route Numbering Committee signing north, south, east, and west routes as suffixed routes in the Interstate Highway System. Three months later, AASHTO rejected the designation, and the highway then got the "225" designation under further correspondence.^[10]

Colorado State Highway 33[]

I-225 had a carrier route during construction that was assigned as State Highway 33 (SH 33). It was designated in the north portion of the freeway that was preexisting, which ran from I-70 to SH 30 (6th Avenue). The route was formed in 1966 and was decommissioned in 1968 as part of the state highway renumbering in effort to eliminate the carrier routes of U.S. Routes and Interstate Highways.^[11][12]

Construction and expansion[]

The Dayton RTD station in Aurora is located in the center of I-225.

Construction on I-225 began in May 1964 at I-70. A section from Colfax Avenue to Sixth Avenue was opened in 1966. Five years later, a segment between Mississippi Avenue and Parker Road was opened, and construction began on another segment south of Parker Road, completed in May 1975. The rest of the route between Yosemite Street and I-25 was completed in May 1976.^[2] Immediately after the completion of the freeway, improvements at the SH 30 (6th Avenue) interchange were underway involving the overpass. Reconstruction of the freeway between 30th Avenue and Smith Road took place between October 1992 to August 1994, which involved bridge replacements over Toll Gate Creek and Smith Road that were completed by August 1990 in an effort for the reconstruction project. Two months after the reconstruction project, the I-70/I-225 interchange reconstruction went underway, which involved widening I-225 from I-70 to Smith Road and improvements to the flyover ramps at the interchange that was completed in April 1995. From February 1996 to November 1997, I-225 was expanded to six lanes between Toll Gate Creek and Colfax Avenue and between Colfax and 6th Avenue by December 1997. A new interchange at Alameda Avenue was completed and opened in 2002 and a new flyover ramp at Parker Road began in September 2000 to complete the interchange between Parker Road and I-225. Another interchange at 17th Place was added and opened on February 15, 2013. The portion from I-25 to SH 83/Parker Road was rebuilt as part of the T-REX Project completed in 2006.^[13] The highway was later widened between Parker Road and Mississippi Avenue to six lanes, as part of a project to widen the entire freeway to I-70; construction on this portion took place between May 2012 and November 2014.^[14] A light rail line was later added along the freeway that begins at I-225's southern terminus at I-25 and runs in between the Interstate from I-25 and Parker Road and then parallel running parallel as it enters Aurora, making I-225 one of the few Interstates with a light rail line in the median. Construction of the light rail line began in spring of 2012 and opened to the public in 2017.

Exit list[]

County	Location	mi[1]	km	Exit	Destinations	Notes
City and County of Denver		0.00	0.00	1A-B	I-25 / US 87 – Colorado Springs, Denver	I-25 exit 200; signed as left exit 1A (south) & 1B (north); directional T interchange.
Arapahoe	Greenwood Village	0.673	1.083	2A	DTC Boulevard, Tamarac Street	Signed as exit 2 northbound
		1.333	2.145	2B	Yosemite Street	Southbound exit and northbound entrance
	Aurora	3.946	6.350	4	SH 83 (Parker Road)
		5.373	8.647	5	Iliff Avenue	Partial cloverleaf interchange
		6.886	11.082	7	Mississippi Avenue
		7.921	12.748	8	Alameda Avenue	Offset single-point urban interchange
		8.953	14.408	9	SH 30 (6th Avenue)
Adams		9.901	15.934	10A	I-70 BL / US 40 / US 287 (Colfax Avenue)	Signed as exit 10 southbound
		10.151	16.336	10B	17th Place	Southbound exit is via exit 10. Opened on February 15, 2013.[15]
Adams–Denver county line	Aurora–Denver line	11.997	19.307	12A-B	I-70 / US 36 – Denver, Limon	I-70 exit 282; signed as left exit 12A (west) & 12B (east); directional T interchange; access to Denver International Airport
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Incomplete access

See also[]

•  Colorado portal
•  U.S. Roads portal

References[]

External links[]

Route map:

• Colorado Routes 200-233