NECR Bridge 35.01 Replacement in Royalton, VT - 2024

ECI's Client: Vermont Agency of Transportation (VTrans)

Completion Date: Fall 2024

Subcontractors: 

• HUB - Drilled Shafts

• ADA - Traffic Control

• Buckingham Structural Movers - Transporting the bridge on SPMT's

• CCS - Crane

• Lafayette - Guardrail

• LD Safety Markings - Line Striping

• Windsor County Sherrif

• GTR

• NECR

ECI contracted with VTrans to replace NECR Bridge 35.01 over Route 14 in Royalton, VT. The existing 26’ clear span bridge was only 12’ 1” above the roadway. Because of the size the bridge choked traffic down to a single lane with no signals and a blind approach from each direction. Due to its low height, the bridge was a high strike-risk, was hit multiple times while ECI was on site, and in the past had been hit hard enough to mangle the outside beams and knock the tracks off alignment. The new bridge is a 125’ steel girder bridge with an improved vertical clearance of 14’ 6” and allowed for Route 14 to be realigned and widened to 30’ from shoulder to shoulder with clear visibility. The contract provided for two full construction seasons with four relatively short railroad closures and one 28-day highway closure. ECI completed this project using 3 railroad closures and one 21-day highway closure.

Year 1 the crew focused on installing 4 drilled shafts, excavation support, setting as much of the precast for abutment 1 and 2 as possible, installing a temporary ballast deck bridge, raising the track to final grade, installing a stormwater pipe, and building the new bridge off alignment.

Year 2 the crew prepared for the new bridge to be put in, placed the new bridge along with the remaining wingwalls, built the new road, and returned everything to preconstruction condition.

Year 1 - 2023

The new bridge is supported by two precast concrete cap beams which each sit on four drilled shaft foundations. The drilled shafts allowed for accelerated construction since the shafts were installed during normal rail traffic since they sat within the embankments but outside the track bed. Hub Foundation out of Chelmsford, MA was contracted by ECI to install the shafts. Each shaft was comprised of 1” thick 64” OD permanent steel casing that was drilled up to 24’ through the soil. They then cleaned out inside the casing via soil bucket and once it hit rock they proceeded to drill another 10’ below the bottom of the casing to create a 56” diameter rock socket. After completion of the drilling a 8,880 pound rebar cage with integrated Crosshole Sonic Logging tubes was positioned in the casing via string and plumb bob along with 14’ long 1 3/8” anchor bolts and then self-consolidating concrete was poured via tremie method. The pour progressed until all groundwater was pushed up and out of the shaft then several additional yards of concrete were pumped into the shaft to ensure all the bad concrete was out. We hired GTR (Geosciences Testing and Research, Inc.) to monitor the CSL tubes to detect voids or inclusions in the concrete after the pour. Hub was responsible for drilling the shafts and pouring the concrete while ECI owned construction of the work platform and SOE, cage and anchor bolt setting, and lift support. ECI’s in-house engineers designed the waste block retaining walls and embankment supporting sheetpiling.

During the first and second railroad closure crews would remove track, excavate, place as much precast as possible for each abutment, cover the precast in plywood and plastic to protect it and then bury it and replace the track. Setting as much precast as possible during closure 1 and 2 allowed for better time management and execution during the 3rd closure.

The first railroad closure started Friday at 6am and ended Sunday at noon. During this closure two retaining walls (83 kips each) and the abutment 1 cap (112 kips) were set.

The second railroad closure ran from Thursday at 6am to Sunday at noon. During this closure two retaining walls (79 kips and 86 kips), two wing walls (91.8kips and 21.8 kips), a wingwall footing (85.5 kips), and the abutment 2 cap (117 kips) were set. Our team did an incredible job setting this footing as the designer stepped it 5 times across this abutment which added to the difficulty and the need for extra grouting and phased backfilling. Another unique challenge our team faced was that wingwall 4 was too heavy to be cast monolithically with its footings and too tall to be shipped upright. This meant that we had to trip the precast, which we have done before but never with precast whose height varied. Our in-house engineers calculated how to make this possible and opted to use a rated turnbuckle to get the lengths just right. To give you a little picture, when hooked up on the trailer the distance from the spreader to the hooks was the same but as the concrete was picked up the rated turn buckle caused the spreader beam to transition from a relatively steep angle to dead level. Everyone on site held their breath as this happened but the wingwall was lifted and placed without any issues.

In addition to the work next to the railroad, our crew worked on a 670’ run of 30” storm pipe from the road, under a private road, through a field to the river. Our crew worked closely with those living on the private road to communicate when work would be occurring and providing traffic control in the form of detours and temporary signals.

In the fall we installed a new temporary ballast deck bridge. While this was not part of the contract this extra step allowed us to raise the track 3.5’ to final grade before the extended closure. We used an old open-deck bridge we removed and replaced in 2017 as the starting point of our design. Our team fabricated top and bottom cover plates to hold the ballast stone and a pair of helper beams to support the knee braces. Once the temporary bridge was in place the railroad crew came in and installed ballast to raise the rail. In order to accomplish this, they placed ballast 725’ north and 1,250’ south of the bridge to allow for the 3.5’ rise in the rail necessary for the new bridge.

Our crew worked from mid-November to the end of December building the new bridge in the laydown area. Our in-house engineers created a steel erection plan that included girder lateral support, crane picks, lateral-torsional buckling checks, temporary foundations and careful sequencing to avoid inducing unintended stress on the structure. This was necessary as the bridge would sit in the laydown area completed from December 2023 to July 2024. High Steel brought the girders which weighed about 400,000 lbs in 4 loads and ECI spliced them on-site. Each splice required 608 bolts. It took a crew of 6 to construct the steel and 5 to construct the deck.

Year 2 - 2024

Work resumed late in the spring when the crew focused on what was needed to prepare for the upcoming closures.

Our third and final railroad closure was a 134 – hour closure that was inside of the 28- day highway closure that started at the beginning of July. For this railroad closure we had about 45 guys on site working in rotating shifts around the clock. The first thing we did was remove the track, ballast and temporary bridge. We then carefully excavated around the abutments we set in the previous closures. Route 14 was removed and the area prepped for the Self-Propelled Modular Transporter to move the bridge into place. Buckingham Structural Movers were subcontracted to move the bridge. It took them 3 days to jack the bridge and get the SPMT’s in place to support the bridge. On July 2nd they did a test run to make sure everything was working and on July 11th the bridge got moved into position. Once the bridge was set on the abutment our crews went to work to restore the road and set the tracks once the grout was cured.

Once the railroad closure ended and the track was completed our crew worked to prepare Route 14 for paving, paved the new road and restored the areas disturbed during construction.

Congratulations to our Superintendent Ken and the crews who made this project a success. It was completed ahead of schedule and under budget and in 2024 this project was awarded AGC/VT Best Builder Award for Specialty Innovation – Civil Highway.