Design

Reconstruction of the I-25 Corridor through the City of Trinidad replaced the existing aging infrastructure with a facility that meets current highway design and safety standards. The new facility provides a safe highway that accommodates current and future traffic demands.

Reconstruction of I-25 includes multiple construction projects. CDOT has completed the Phase I construction project. Phase II NB began in April 2007 and Phase II SB began in July 2009. Phase II was completed in early 2012. A future Phase III will follow as construction funding becomes available.

Phase I	Construction of the SH 12 (Highway of Legends) Extension Construction of the SH 12 extension from I-25 across the Purgatoire River to Main Street began in September of 2003 and was completed August 2004. This section of SH 12 was officially open to the public in a ribbon cutting ceremony on August 3, 2004. The new extension provides a safe connection from SH 12 to I-25 via the Main Street interchange. This connection also guides motorists traveling from the west to downtown Trinidad, via Main Street, into the El Corazon de Trinidad Historic District. (More info: Archive: Phase I Construction History and Photographs) Project Area Map - click to view enlargement
Phase II NB	Reconstruction of Northbound I-25 Major elements of Phase II NB reconstruction were completed in September of 2009 including: reconstruction of approximately 1.3 miles of northbound I-25 from Van Buren Drive to Commercial Street, reconfiguration of the Main Street and Commercial Street interchanges and replacement of the NB viaduct and structures at Main Street and the Purgatoire River.

Progress Map - view Phase II NB Reconstruction (updated 2012) click to view enlargement

	Work for Phase II NB also included: replacement of the AMTRAK depot, construction of a paved parking area adjacent to the new depot, construction of a water quality detention pond, and improvements to Purgatoire River Park. Phase II Design Overview Design of the realignment of I-25 and associated interchanges through the City of Trinidad was based on bringing the facilities up to the latest interstate design and safety standards. I-25 Trinidad construction project - Phase II NB Design Aesthetics - click to view enlargement Aesthetics was also an important consideration during design because the interstate bisects the City of Trinidad. Architectural elements of the historic downtown buildings as well as the naturally occurring sandstone bluffs influenced project aesthetics. For example, the arch form found in many of Trinidad’s buildings was replicated in an arch-shaped reveal on the viaduct piers. Trinidad’s famous brick street pavers were incorporated in local street crosswalks. Finish treatment on project retaining walls replicates sandstone blocks. Minimizing right-of-way purchase also influenced the final design. Retaining walls were used extensively to minimize encroachment of roadway side slopes onto properties adjacent to the highway. Phase II NB features: Phase II NB Construction NB Viaduct Length = approx. 2000 Feet Number of Spans = 14 Longest Span = 250 Feet Retaining Walls Constructed = 4500 Linear Feet Concrete (total project) = 15,000 Cubic Yards Reinforcing Steel (total project) = 3 Million Pounds Purgatoire Park: Amenities included in NB = two benches, picnic table, two trash containers Approximately 1000 trees & shrubs Reconstructed NB I-25 from Goddard south to Van Buren. Replaced NB viaduct structure and bridges carrying NB I-25 over Main Street and the Purgatoire River. Removed NB I-25 on-ramp at Van Buren. Reconstructed NB I-25 off and on-ramps at Main Street. Reconstructed NB I-25 on-ramp and a NB I-25 off-ramp added at Commercial St. Highway lighting is LED guidance lighting mounted on the inside face of guardrail in lieu of the traditional high mast lighting. This is the first instance in the Country of LED guidance lighting being utilized on an interstate highway. Ramp lighting is traditional mid-mast lighting. This project is a CDOT Research test case for the use of self-consolidating concrete (SCC). SCC was utilized in the Purgatoire River and Main Street bridge abutments. The depot building was replaced with a new AMTRAK structure and a paved parking lot was constructed adjacent to the new depot. (Completed during Phase II SB.) Railroad crossing arms installed at University Street, Nevada Avenue, and Commercial Street. Improvements made to Purgatoire River Park included two benches, a picnic table, and two trash receptacles. A water quality pond was constructed near the viaduct to filter stormwater runoff from the viaduct before discharging into the Purgatoire River. (Completed during Phase II SB.)
Phase II SB	Reconstruction of Southbound I-25 Phase II SB Reconstruction rebuilt I-25 from just north of Commercial Street to just north of Van Buren; including reconstruction of the viaduct, mainline bridge over the Purgatoire River and the Main Street overpass bridge. Work also included reconstruction of the southbound off and on-ramps at Main Street, a new southbound on-ramp at Commercial Street, and removal of the southbound exit ramp at the Van Buren Drive interchange.

Progress Map - view Phase II SB Reconstruction (updated 2012) click to view enlargement

	Phase II SB consists of the following features: SB I-25 reconstructed from Commercial south to Van Buren. Bridges carrying SB I-25 over Main Street and the Purgatoire River, and the SB viaduct replaced. Decorative brick bases added to the NB and SB viaduct pier columns. The viaducts, bridges and walls constructed in both NB and SB phases were stained colors to match the surrounding environment. The SB I-25 off-ramp at Van Buren removed. SB I-25 off and on-ramps at Main Street reconstructed. At Commercial Street, the SB I-25 on-ramp added. Highway lighting similar to NB I-25. The Purgatoire River Trail extended from where it currently ends near the I-25/Purgatoire River bridges south to Van Buren Drive. A parking lot with landscape features constructed under the viaducts. A pocket park with picnic tables added south of Commercial Street between the NB off-ramp and the railroad tracks.
Phase III	Construction of New Interchange At MP 12. A future Phase III will reconstruct I-25 from Van Buren Drive south to Sopris Road, remove the remaining portion of the Van Buren interchange, and construct a new interchange at MP 12. Design and construction of Phase III will occur as funding becomes available. Project Area Map - click to view enlargement

Self-Consolidating Concrete
CDOT’s Research Branch provided funding for Phase II NB to test self-consolidating concrete (SCC) in a field condition. Advantages of SCC is that it can be placed without vibration due to its high fluidity, it flows well around highly congested areas of reinforcing steel and SCC typically has an excellent surface finish devoid of blemishes which minimizes the amount of finish work required on the concrete after concrete forms are stripped.

SCC is already utilized extensively in the precast concrete industry where concrete is placed in a highly controlled environment. CDOT tested the use of this concrete in field conditions, to see if SCC can be regularly specified for projects where concrete placement may be difficult due to inaccessibility and where there is a large amount of reinforcing steel required for a structural element.

Because of the high fluidity of SCC, it creates higher pressures on formwork than normal concrete. For this project, the Contractor was required to perform tests showing CDOT that their SCC mix design does flow readily around a congested area of reinforcing steel, and that forms can withstand the additional placement pressures.

LED Highway Guidance Lighting
One concern the City of Trinidad had with the reconstruction of I-25 was light trespass from new highway lighting. Clanton and Associates, the lighting design engineers for the project, proposed a new LED guidance lighting system that greatly reduces or even eliminates light trespass. Instead of lighting the entire surface of roadway as with conventional highway lighting, the LED fixtures wash the traffic face of guardrail with subtle lighting to guide motorists along the roadway.

Features of the LED lighting include:

• LED lamp life of 50,000+ hours
  
• Lighting is recessed into guardrail
  
• Lighting is directional with low glare
  
• Intended for “guidance” of traveling public

LED highway lighting is a new technology in the United States, the Trinidad Reconstruction Project was the first project in the United States to utilize this technology. Implementation of this LED lighting system was partly funded by the CDOT Research Committee. The Committee is involved in monitoring the LED’s performance. Depending on the success of this project, the LED lighting system may become one of the light system standards utilized by CDOT for future projects.

Water Quality Pond
A water quality pond was placed below the elevated portion of Interstate 25 just north of Nevada Avenue. It collects storm drainage from the roadway, bridges and other areas of the project. This water quality pond allows impurities to settle out of the storm water over a 40 hour period prior to discharge into the Purgatoire River. The pond was landscaped with a variety of shrubs and native grasses with river cobbles and landscape boulders. The addition of this type of pond is one of CDOT’s ways of minimizing the environmental impacts that highways have on streams.