Proposed Action Alternative

The proposed action will incorporate many design improvements to address the traffic operations and safety needs of the corridor. The proposed action includes the following project elements:

  • Element 1 – Reconstructing I-25 from 84th Avenue to Thornton Parkway to a typical cross-section of four 12-ft general-purpose lanes, a 12-ft Express Lane along the inside travel way, a 4-ft buffer between the Express Lane and nearest general purpose lane, a 12-ft outside auxiliary lane between each interchange, and 12-ft inside and outside shoulders in the northbound and southbound directions. The four northbound general-purpose lanes will extend to 104th Avenue with the fourth northbound general purpose lane exiting as the 104th Avenue off-ramp
  • Element 2 - Constructing a median transit station and transit-user pedestrian bridge for the Thornton Park-n-Ride just south of 88thAvenue
  • Element 3 - Removing the existing concrete box culvert underneath I-25 at the Thornton Park-n-Ride Station, currently used by transit-users and pedestrians/bicyclists on the Niver Creek Trail crossing I-25
  • Element 4 - Separating the northbound and southbound lanes of I-25 with a concrete barrier and separating the Express Lanes from the median bus station and bus lanes with a concrete barrier
  • Element 5 - Replacing the 88th Avenue bridge over I-25. The 88th Avenue bridge over I-25 will accommodate the Niver Creek Trail
  • Element 6 - Realigning the Niver Creek Trail north of 88th Avenue and west of I-25 approximately 50 feet to the west. Constructing a separate concrete box culvert underneath 88th Avenue for the Niver Creek Trail to access the Thornton Park-n-Ride Station on the west side of I-25. Widening the new 88th Avenue bridge over I-25 to include the Niver Creek Trail crossing of I-25
  • Element 7 - Constructing retaining walls along the 84th Avenue northbound on-ramp to I25, southbound I-25 off-ramp to 84th Avenue, and along I-25 at the Thornton Park-n-Ride station
  • Element 8 - Reconstructing the Niver Creek Tributary L concrete box culvert crossing underneath I-25 between 84th Avenue and 88th Avenue
  • Element 9- Replacing an existing noise barrier near 88th Avenue that must be moved to construct the Proposed Action
  • Element 10 - Constructing permanent roadway stormwater draining water quality features for roadway runoff and accommodating off-site stormwater flows along I-25.

Figure 3: Proposed Action Elements