Crews Divert Purgatoire on I-25 Job

Thu March 19, 2009 - West Edition
Rebecca Ragain



Just north of the New Mexico border, at the foot of 9,665-ft.-tall (2,950 m) Fishers Peak, lies Trinidad, Colo., population 9,000. Interstate 25 passes through the city, connecting to Santa Fe and Albuquerque to the south and to Colorado Springs and Denver to the north.

The Colorado Department of Transportation (CDOT) has deemed the structures on this section of Interstate 25 (I-25), which was originally constructed in 1955, obsolete. As a result, a $37-million reconstruction of northbound I-25 is currently under way.

The Phase II Northbound job — Phase I, which consisted of an extension of SH 12 over the Purgatoire River, was completed in 2004 — is horizontally and vertically realigning approximately 1.3 mi. (2 km) of I-25’s northbound lanes from Van Buren Drive to Commercial Street.

Three interchanges (Main Street, Commercial Street, Van Buren) are being reconfigured to accommodate the roadway’s shift. An on-ramp at Main Street and an off-ramp at Commercial Street are being constructed.

The project also encompasses the replacement of three major structures: bridges crossing Main Street and Purgatoire River, and a viaduct that carries interstate traffic over city streets and a railroad.

Littleton, Colo.-based Lawrence Construction began the design-build job in April 2007 with demolition of the Main Street and Purgatoire River bridges. Nearly two years later, in mid-February, the two new structures — separated from each other by a couple hundred yards of roadway — are approximately 85 percent complete.

“It wasn’t a nightmare job but it definitely had its challenges,” summarized Dean Neffendorf, Lawrence Construction’s structures superintendent.

Purgatoire River posed one of these challenges, which affected bridge construction. Neffendorf said: “Access around the river was an obstacle we really had to work around. We were able to divert the waterflow to one side through some large culverts we put in, then backfill ’til we could get over the river. Diverting the water allowed us to gain access to areas we couldn’t without.”

To set the girders from piers to abutment, a 400-ton (360 t) and a 250-ton (226 t) crane (leased from Winslow Crane Service Co. out of Englewood, Colo.) were set up on opposite sides of the river.

Aside from the leased cranes and the trucking, which was done by Felix Chavez & Son Construction, most of the heavy equipment is from Lawrence Construction’s fleet, a mix of Caterpillar, John Deere, Komatsu, Link-Belt and others.

At present, the MSE walls along the roadway leading up to the bridges still require work. However, that process is on hold until the weather warms up and crews can backfill in preparation of switching traffic. Project-wide, subcontractor Slaton Bros. is installing several hundred thousand square feet of MSE walls to prevent the roadway’s slopes from encroaching on properties adjacent to the highway.

Other subcontractors include Redwing Electric, Castle Rock Construction Company for paving, and Anderson Drilling for caisson drilling.

The 2000-ft viaduct, the largest aspect of the reconstruction, is approximately 70 percent complete. The new structure is 100 ft. (30.5 m) longer and 7 to 11 ft. (2 to 3.3 m) taller than the original viaduct. Construction is proceeding from north to south, with the portion of superstructure over the railroad being constructed last. As of mid-February, crews were preparing to set drop-in segments over the railroad tracks.

“It’ll be kind of a unique structure, when it’s done,” said Neffendorf.

He explained: “We’re crossing a railroad at a pretty sharp skew, so the span had to be 260 feet and you can’t bring in a girder that big…We had to set cantilever girders and this piece will be set in between. It’s the first time this has been done with this type of girder [concrete pre-cast tub girder].”

Phase II Northbound is due for completion in June. Work is proceeding on schedule, with crews ramping up for the last stages to take place this spring.

Neffendorf said, “There’s always a little flurry toward the end of the job to make sure all the loose ends get tied up, but with the right amount of manpower we should be able to do it without too much of a rush.”

Also in June, Lawrence Construction plans to begin reconstruction of the southbound section of I-25 through Trinidad — a $44-million project for which design work is already under way. CEG