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Interstate 225

Length: 12 miles (I-25 in Denver to I-70 in Aurora)
Exits: 10
Counties: 3 (Adams, Arapahoe and Denver )
Cities: 2 ( Aurora and Denver )
Start of Construction: 1964
End of Construction: May 21, 1976
Initial Construction Costs: $27.5 million

National Impact

I-225 connects with I-25 and I-70, allowing motorists to link with states east, west, north and south of Colorado.

I-225 was built in stages coming south from I-70. It reached 6th Avenue by 1966, Mississippi Avenue by 1970, Parker Road by 1972, and I-25 by 1977. I-225 was widened to three lanes each direction between 6th Avenue and I-70 in the late 1990s. Also the 3-level stack at I-70 was reconstructed about the same time to eliminate left entrances/exits. The City of Aurora fronted money for a new interchange at Alameda Ave , and that opened in Fall 2000. Interchange reconstruction at Parker Road , including adding a loop and a flyover, were completed in Spring 2002. In 2003 improvements where completed at Iliff Avenue which included adding loop ramps.

Construction Timeline

May 1964 Construction of I-225 begins at I-70

June 1966 A one-mile segment of I-225 between Colfax Avenue and East Sixth Avenue opens to traffic.

1969 Bridges at Mississippi Avenue were constructed

September 3, 1971 Another 2.1-miles segment of I-225 opens to traffic between Mississippi Avenue and Parker Road .

May 27, 1975 A two and half mile segment of I-225 between Parker Road and Yosemite Street opens to traffic. Construction begins in 1971.

1976 Bridges at Mississippi Avenue were widened

May 21, 1976 The remaining 1.2 miles of I-225 between Yosemite and I-25 opens to traffic. Costs: 1.6 million; Contractor: Ramsour Brothers, Inc. of Castle Rock, CO

1976 Improvements to the I-225/6th Avenue Interchange Begins Cost: $624,768; Contractor: Peter Kiewit Sons' Co.

July 1990 An overlay project between Parker Road an I-25 begins. Cost: $800,000; Complete: August 1990

August 1990 Replacement of the I-225 bridge over Sand Creek is complete. The new bridge is longer and wider to accommodate future widening. Cost: $4 million

October 1992 Project begins to replace the structures over Smith Road and the Union Pacific Railroad. Also, reconstructs I-225 between Sand Creek (about 30 th Avenue) and Smith Road . Cost: $6.8 million; Contractor: Edward Kramer & Sons, Inc. Complete August 1994

March 1994 The second phase of I-225 and I-70 interchange reconstruction project begins to widen I-225 between Smith Road and I-70. Cost: $4 million; Contractor: SEMA Construction, Co., Inc. Complete: Oct. 1994

April 23, 1994 The new flyover ramp from westbound I-70 to southbound I-225 opens to traffic. $18.2 million project; Contractor: SEMA Construction, Co., Inc; 1,967-foot ramp; 50 feet above I-70; Construction began in March 1993.

April 1995 The projects that reconstructed the ramp from eastbound I-70 to southbound I-225 and the northbound I-225 to eastbound I-70 ramp is completed. Cost: $4 million. Started in Fall 1994

February 1996 Constructs begins to widen I-225 between Colfax Avenue and Sand Creek to six concrete lanes. Cost: $9.8 million; Contractor: SEMA Construction Co., Inc. ( Englewood , CO) Completion: November 1997

July 1996 Construction begins to widen the Mississippi Avenue bridge over I-225. The new bridge will accommodate three through lanes in both directions and two left turn lanes in each direction to get onto I-225. Cost: $5.1 million; Contractor: Edward Kraemer & Sons Complete: May 1998

November 1996 Construction begins to widen I-225 to six lanes between 6 th Avenue and Colfax Avenue . Cost: $5.12 million; Contractor: Castle Rock Construction Co. Complete: December1997

September 1997 The new flyover from northbound I-225 to westbound I-70 opens to traffic. Cost: $7 million; Contractor: Castle Rock Construction Co. Started: March 1997 to Summer 1998

November 1997 Voters approved the construction of a $20 million interchange at I-225 and East Alameda Avenue . I-225 was built in I-225 without an interchange at this location.

February 1998 Construction begins on a sound wall from Parker Road to Yale Avenue on I-225. The project also includes the widening of the bridge over the emergency spillway on Parker Road . Cost: $4.5 million; Contractor: Hamon Contractors, Inc.; Completion: Spring 1999

December 1999 Construction of the second phase of I-225/Alameda interchange project begins. Cost: $12 million; Contractor: Hamon Contractors, Inc.; Completed in March 2001

September 2000 Construction of a flyover ramp from northbound Parker Road to southbound I-225 begins. Cost: $48 million; Contractor: SEMA Construction Co, Inc.

June 2001 Construction begins on the new northbound I-225 off-ramp to Iliff Avenue and a new loop ramp from eastbound Illif Avenue to northbound I-225. Cost: $3.1 million; Contractor: Hamon Contractors, Inc.

2002 New interchange at Alameda and I-225 opens to traffic

April 2003 Construction begins to replace the bridges at 2 nd Avenue and 6 th Avenue over I-225. Cost: $12.3 million; Contractor: Hamon Contractors, Inc. Complete: March 2005

As part of the T-REX project, construction begins to widen I-225 between Parker Road and I-25 to three lanes each direction

CDOT Personnel

Neil Rickli Bob Mjoen
Al Eastwood Mark Myers
Abe Lavassani Dick Brasher
Larry Warner Reza Akhavan
Gary Schultz Dave Clark
Stan Ihlandfeldt John Basner
Mitch Kumar Ed Bullard
Telecia McCline Jerome Milender
George Warda  


Other Contractors:

A.S Horner Construction Co., Inc.
Winslow Construction Co.
Lawrence Construction Co.


Economic Impacts

The construction of the new Alameda Avenue interchange was vital to the City of Aurora.

Contact Information

CDOT Communications Office
dot_info@state.co.us