4th Street Bridge Advisory – Major Traffic Switch Friday Morning

April 14, 2010 – Southeastern Colorado/CDOT Region 2 – PUEBLO – The Colorado Department of Transportation (CDOT) is getting ready to move all traffic on the current 4th Street Bridge onto the new westbound structure by 7 a.m. on Friday, April 16.

Drivers should expect occasional traffic stops and delays up to 10 minutes through the area on Thursday as preparations are made for the realignment.

Traffic is being moved to allow the eastbound bridge to be demolished over the next four to six weeks. In addition:
• Eastbound and westbound traffic will remain in a single-lane configuration on the new bridge
• No left turns will be allowed at the Elmhurst Place/Pearl Street intersection while construction is taking place near the west end of the bridge
• Pedestrians access will be limited to the new, north sidewalk on 4th Street due to demolition of the old bridge
• Traffic will be traveling on an unfinished road surface and may experience bumps, which will be removed when final paving is completed later this year
• Shoulder closures will remain on the new westbound bridge, allowing access for eastbound bridge construction
• The loop ramp from eastbound 4th Street to Midtown Center will remain closed until bridge demolition is complete
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In addition, CDOT has closed the Arkansas River Trail under the bridges to maintain safety for pedestrians and bicyclists. It is scheduled to reopen on June 1, 2010.

The new eastbound bridge is expected to open to traffic in its final configuration in December 2010. Landscaping and other finishing work will take place in spring 2011, with project completion scheduled for summer 2011.

4th Street Bridge Trail closure begins this week

March 29, 2010 – ADVISORY – Southeastern Colorado/CDOT Region 2 – PUEBLO – The Colorado Department of Transportation is closing the Arkansas River Trail, under the 4th Street Bridge (State Highway 96), beginning on Thursday, April 1.

Safety considerations will not allow the path to remain open as demolition work begins on the old bridge structure.

The trail will be closed around-the-clock, including weekends. A signed detour will be place while the trail is closed. It is scheduled to reopen on June 1, 2010.

Pueblo West and county officials have been planning the project, which will be a rebuilding of McCulloch Boulevard south of U.S. 50 West. The county is designing the project. Work is expected to begin in 2011, though some work may begin sooner.

Go to the Pueblo Chieftain to see the entire article.

They will discuss the issue Monday afternoon at a meeting between Pueblo West board members and the Pueblo County commissioners.

The money comes from a ballot measure passed in 2006 that allows Pueblo County to keep whatever tax money it collected above prior-year limits. The time-out from the state’s tax-refunding law was expected to earn the county about $23 million, of which $3.5 million was promised for roads projects in Pueblo West.

Go to the Pueblo Chieftain to read the entire article.

Looking northeast toward downtown Pueblo, the balanced cantilever construction method can be seen in the blue slipform mechanism at the end of the westbound span. The Arkansas River levee is in the foreground. CDOT Photo.

Pueblo’s new Fourth Street Bridge project has hit its halfway point, a nearly four-year, $27.7 million construction job that will give Colorado 96 a graceful twin span crossing of the extensive Pueblo rail yard and the Arkansas River.

The bridge is being built by Flatiron Constructors Intermountain of Longmont with an unusual method designed by FIGG Bridge Engineers, a Tallahassee, Fla., firm with its western regional office in Denver.

The design is a set of three segmental concrete spans built from atop the structure itself via traveling forms that gradually extend out from either side of the tall bridge piers, a method called balanced cantilever construction. There are also two end spans that use cast-in-place construction from the opposite abutments to the first support piers, for a total of five spans.

The concrete approach saved the Colorado Department of Transportation about $5 million in costs over steel. In addition, Flatiron’s low bid was $1 million below CDOT’s engineering estimate.

CDOT’s total cost including design and management is $35.5 million.

Movable form enables cantilevered construction of the concrete span out from the supporting pier without working from the ground level.

The overhead slip forms used in the balanced cantilever method minimize the need for ground equipment and staging underneath the structure. In addition, the concrete design and construction method allowed CDOT to include a main span of 378 feet, the longest concrete span for any bridge in Colorado. That is sufficient width to span the entire Union Pacific portion of the yard – 23 tracks –without having to sink a single pier in the middle of it. The five BNSF tracks will be cleared without a bridge pier as well.

As a result, Flatiron is able to build these artistic spans without requiring any track closures below.

I got a chance to see this construction during a recent trip to Pueblo for a family get-together. While crossing the existing Fourth Street Bridge, built in 1958, it’s easy to see how the new one will improve driver safety. Primarily, it will straighten out a horizontal reverse-curve on the west approach, where Lincoln Street jogs slightly left, then right, then left again to line up with the span.

That’s because the existing four-lane bridge was built to the east of the older one it replaced, resulting in the jogged approach. The new bridge is in the ghost alignment of the pre-1958 structure and lines up more directly with the Lincoln Street approach.

In addition, the east approach curve will be slightly wider and less steep than the current one.

Rendering shows the twin spans clearing the Union Pacific yard, with the BNSF tracks in the foreground.

CDOT investigated rehabbing the existing bridge but found the poor condition of the supporting substructure made that a poor choice. It is rated structurally deficient, with a rating of 26.3 on a scale of 100. It is the lowest rated state highway bridge in all of Pueblo County.

The existing bridge is 1,069 feet long and was built as part of the citywide highway improvements that connected to the Pueblo Freeway project in the 1950s. It consists of seven spans, and five of the piers rise out of the spaces between tracks in the rail yard. Getting rid of them will improve safety in the rail yard as well and meet updated railroad standards for clearances.

UP and BNSF use the large Pueblo yard – formerly part of the Arkansas River floodplain until the levee was built following a disastrous 1921 flood – as a transfer point for many of the coal and freight trains that traverse the Front Range every day.

The project started in December 2007 and the opening is scheduled for June 2011.

As far as staging, FIGG and Flatiron worked out a sequence that will keep vehicle traffic flowing as well.

The first of the two new spans that will be complete is the westbound one, and is being built to the west of the existing bridge. Support piers for the new eastbound span are also being built in between the two. The new bridge’s footprint is almost entirely outside the footprint of the existing structure – except for the easternmost final span of the new eastbound bridge. That means it can’t be connected down to grade on the downtown end until the old bridge is demolished.

As a result, Flatiron will complete and open the westbound bridge, which will temporarily handle all four lanes, allowing for demolition of the current bridge and final completion of the eastbound span.

When completed, the two new bridges will be about six feet apart. They will each have two traffic lanes, with shoulders of six and 10 feet, plus 10-foot multi-use sections for pedestrians and cyclists. They will be wide enough to accommodate three traffic lanes each if needed in the future.

This will be the fourth bridge to cross the Arkansas River here on Fourth Street. On the west side, it connects through to Lincoln Street and then Thatcher Avenue, which takes CO 96 west out of town. To the east, it leads into Fourth Street and then straight out of town toward Avondale.

The first bridge, from the 1880s, was washed out in the 1921 flood. It was replaced with a steel truss bridge in 1924 that then was replaced in the fifties by the current span. The existing bridge cost $1.77 million in 1958, and was the single largest contract among all the roadwork associated with Pueblo Freeway construction.

Post card shows the original Fourth Street Bridge over the Arkansas River.

Construction crews are beginning more extensive work on the new bridge this week and will be narrowing the traffic flow on the existing span.

Essentially, the bridge will handle only one lane of traffic in each direction and the maximum speed limit will be 25 mph. Those lane limits will be in place through November.

Alternate routes over the river are the Main Street bridge, Interstate 25 or Pueblo Boulevard.

Read the entire report at the Pueblo Chieftain.

The document provides a description of the proposed highway improvements and the anticipated effects associated with each alternative. Publishing this document is part of the process that enables highway projects to be eligible for federal funding. The National Environmental Policy Act (NEPA) requires agencies to prepare environmental impact statements for major actions that affect the quality of the human and natural environment.

Issues and factors (resources) studied include economic and agricultural factors, cultural and historic resources, social considerations, potential effects to the natural environment, and more. The project team has partnered with communities along the corridor, federal and state agencies, and with corridor residents and business owners to gather and analyze the information.

The DEIS will be available for public review in 2010. The formal review period lasts 45-days, during which public meetings will be held to gather comments regarding the document. Comments will be accepted in person, and also via phone, U.S. mail, e-mail and the project Web site. CDOT will announce the document’s availability before its release.

Read the entire article at the Lamar Ledger.