Looking east from the middle of Pecos Street toward the railroads' Utah Junction, the four tracks split with the two on the left heading onto a Union Pacific bypass that has increased the number of trains here.

Adams County is set to start construction on an overall $43 million project that will greatly enhance mobility along Pecos Street near Interstate 76, open up redevelopment possibilities and at the same time make FasTracks a little bit better.

Sema Construction of Centennial was awarded a $27.5 million construction contract by Adams County to build the Pecos Street grade separation, a 1,000-foot, eight-span bridge that will take Pecos Street over the Union Pacific Railroad and Burlington Northern Santa Fe Railway tracks between 56th and 62nd avenues, plus access roads down to the properties below the bridge.

Work will start with detour set-up as early as next month.

“We got some very good bids on this project,” said Jeanne Shreve, Adams County transportation coordinator. The contact was $3 million below the engineer’s estimate.

Computer simulation by Adams County GIS Speciallist Joe Suglia shows a view of the Pecos grade separation looking northeast. The four-track crossing is at the bottom of the rendering, while the RTD FasTracks Pecos Junction Station is at the top center, under the bridge.

Union Pacific is providing $14.4 million of the total cost. Up to $5.15 million is coming from the federal stimulus program – this job is definitely shovel-ready – and other federal and local Adams County funds are providing the rest.

No more stopping for an hour or more looking at a coal train parked across Pecos. While it might have given you a chance to catch up on your reading, it wasn’t a good way to get where you wanted to go. A few years ago, Adams County installed turnaround circles on either side of the crossing for traffic to U-turn instead of waiting for parked trains to move.

Rene Valdez, construction manager for Adams County Public Works, said the bridge will be made with concrete girders on piers and will be two lanes wide with sidewalks.

The price drivers will pay for this 22-month project is a total closure of Pecos at the crossing almost to the end of the project in October 2011. Detours will be established first, likely next month. Southbound Pecos traffic will be detoured west on I-76 to Federal, then south on Federal to 56th Avenue, and then east back to Pecos. Northbound traffic will take the same route in the opposite direction.

This will bring a temporary increase in traffic along 56th during construction. The closure means less time and expense for traffic control required when drivers go through a work zone.

Adams County and Sema representatives will host a public meeting to discuss the construction and detour plans. The meeting is tentatively set for the evening of Dec. 9 in Guardian Angels School on 52nd Avenue west of Pecos, Valdez said.

Google Earth view shows the location of the Pecos bridge project on the left with the layout of the railroad tracks that feed into the crossing.

This is a job that’s needed to be done for a long time, but for the huge expense. A lot of trains run through here every day. It’s just west of Utah Junction, the meeting point for BNSF’s Golden Branch, along which the RTD FasTracks Gold Line will run, and its Front Range Subdivision to Boulder, as well as UP’s Moffat Tunnel Subdivision that heads up the Rockies to the tunnel, and its Belt Line connector to the Greeley and Limon tracks in east Denver. Utah Junction also handles trains headed out of UP’s North Yard and BNSF’s adjacent Rennick Yard.

What gave the Pecos grade separation fresh impetus was the 2004 construction by UP of bypass tracks from the Moffat Tunnel tracks on the west to the Belt Line, which is an east-west shortcut parallel to 60th Avenue for trains to reach UP’s Greeley and Limon tracks. The bypass tracks make up two of the four tracks at the Pecos crossing.

The bypass greatly increased the number of trains,which sometimes come to a stop with freight or coal cars blocking Pecos for lengthy periods of time each day.

To expand to full screen and read the captions, first click on the “play” button and then click on the box that will appear at the lower right corner — with the four little arrows pointing outward. When the full screen appears, click on “Show Info” at the menu bar on the top right.

When the bridge is completed, expect this area to open up.

It’s been one plugged-up island in a sea of regional traffic, smack in the middle of a triangle bounded by I-76, Interstate 25 and Interstate 70. There is a lot of industrial development, landfills, ponds and some residential through the Clear Creek Valley that traverses it.

“You have tremendous access from the highway system,” Shreve said. “t’s a great place for a commuter park-n-Ride.”

Adams County already is laying groundwork via its Clear Creek Valley Transit Oriented Development Plan for more mobility improvements. A new east-west Clear Creek Parkway along the south side of the creek plus a new collector road that could connect Pecos to Huron or Broadway to the east are on the drawing board.

And RTD will have the space it needs to construct a joint FasTracks station on the east side of Pecos, where Gold Line trains between Denver and Arvada/Wheat Ridge can share passenger transfers with the Northwest Rail trains serving Denver, Westminster, Broomfield, Boulder and Longmont.

Looking southeast down the BNSF track on the east side of Pecos Street, this is the site for RTD FasTracks joint station on the Gold Line and Northwest Rail corridors. Building the grade separation makes the joint station possible.

FasTracks is next to the BNSF Front Range Subdivision that head toward Boulder at this point. If the Pecos bridge were not to be built, track geometry would have precluded RTD from including a Northwest Rail stop there. The Gold Line station instead would have to have been built on the west side of Pecos, beyond the point where it splits from shared trackage with the Northwest Rail Corridor. Northwest Rail passengers would have been required to go into north Denver’s planned 41st Avenue station to transfer in the opposite direction to Gold Line trains.

“It really does come down to geometrics,” said Gold Line Project Manager Ashland Vaughn. “We have to do a series of turnouts there and it turns out to be a diamond that falls right in the middle of Pecos Street. You don’t want to have paving around those switches.”

RTD needs to have up to 600 feet of straight track section to put in a station platform.

Adams County put a lot of thought and planning into what the project would look like. This provides a lesson in how different alternatives are weighed and chosen.

A lengthy bridge is expensive, and with the separation between the UP and the BNSF crossings it was possible to build two bridges. The county engaged in a nearly year-long process of looking at different design alternatives. It is downhill going north from the UP tracks toward the BNSF crossing. Because of that, it extended the distance that the ramp back down to ground level would have to go while still maintaining a maximum 5 percent grade.

The reason that was an important factor is that this involves the north approach to the bridge. Since it slopes away from the angle of the winter sun, making it too steep would invite a persistent winter icing problem and potential maintenance headache. A gentler grade on the north approach helps make use of winter sunlight to melt ice and snow.

The estimated cost difference between building two bridges and a larger single one was $3 million, the larger one being more expensive but promising less maintenance.

“We wanted to make sure we were doing the right thing,” Shreve said.

Looking toward the southeast from Pecos Street, the Union Pacific Railroad tracks head toward Utah Junction and the North Yard.