Tub Crossing Repair
The Job
This tub crossing repair was done for a short line railroad in New Jersey. The sandy soils of South Jersey are great for growing produce and mining pure silica sand. While most of the produce is shipped by truck, a lot of the silica is shipped by rail. The rails inevitably cross the roads, and many of the crossings are at grade.
The Challenge
A short-line railroad was experiencing significant settlement and pumping of multiple precast modular crossings in the Vineland & Millville areas. Each crossing saw significant truck traffic, primarily from aggregate mining, and also significant heavy haul rail traffic from transporting sand.
Voids below the panels were holding water due to poor drainage. Each time a truck or train passed over the panels, they deflected downwards. This deflection pumps base material out from under the crossing, causing settlement.
The Solution
Working with a rail maintenance contractor, CJGeo performed polyurethane grouting on a total of four precast tub crossings in the area, using CJGrout 40NHL. Each crossing repair took a single day. Polyurethane grouting allowed for the immediate resumption of automobile traffic, and rail traffic. Th CJGeo crew installed supplemental bolting to address the deterioration of the panels resulting from the extensive movement of the panels.
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Industrial Short Line Tub Crossing Repair
The Job
This short line tub crossing repair project is located in Baltimore, Maryland. Sparrows Point, in Baltimore, Maryland is a brownfield site. It’s transforming from being steel manufacturing to industrial and logistics use. From it says as a heavy manufacturing facility, there is an extensive freight rail network throughout the site, with many grade crossings subject to significant heavy truck traffic & heavy haul rail traffic.
The Challenge
A precast tub-style grade crossing on a road feeding a metals recycling plant developed a 2.5″ belly. The local FRA inspector instructed the railroad to correct the settlement.
The Solution
CJGeo performed structural polyurethane grout injection to fill voids below the panels. And then lift them back into their correct alignment. The work took just a few hours, without disruption to the rail or auto traffic.
CJGrout 40NHL is a four pound per cubic foot geotechnical polyurethane grout. It’s specifically designed for high dynamic load environments like rail, port, and airfield traffic. CJGeo’s crews use 40NHL for modular grade crossing repairs to ensure the longest life repair possible.
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NC Tub Crossing Repair
THE JOB
This NC tub crossing repair project is located in Charlotte, North Carolina. The 8′ long panels of tub-style grade crossing settled. As a result, MOW placed a speed restriction on the crossing. This affected passenger schedules. The settlement affected three panels. The belly in the slabs was approximately 2 inches. The crossing deflected slightly with heavy truck traffic. The crossing deflected significantly with rail traffic.
THE CHALLENGE
The repair had to be completed in just a few hours, to avoid disruption to rail traffic. The repair had to allow for immediate resumption of rail traffic, and tolerate tamping of the adjacent truck during the repair. Additionally, the tub crossing repair had to be done in a manner that did not disturb the adjacent asphalt pavement.
THE SOLUTION
High-density geotechnical polyurethane grouting to stabilize and lift the affected modular grade crossing panels. Geotechnical polyurethane grouting is far superior to mudjacking, in that the process is faster, and can more easily ensure a complete filling of voids under the crossing panels. Lifting precision of fewer than 0.1 inches is standard.
A CJGeo modular grade crossing repair crew filled the voids and corrected settlement in a few hours. During the tub crossing repair, the rail system used a tamper on the approaches. This helps ensure the longevity of the grouting repair. The structural polymer grouting process used here is sometimes referred to as slab jacking.
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Industrial Driveway Crossing Repair
The Job
This industrial driveway crossing repair project is located in Frederick, Maryland. MARC’s Brunswick Line’s Frederick extension passes through multiple industrial sites & driveways. This particular crossing served as the driveway of a ready mix concrete operation, so saw extensive high dynamic loading in a wet environment.
The Challenge
The repair had to be performed without disrupting either rail or industrial traffic. There was a four-hour window between the last morning train and the first evening train for performing the repair to the eight modular tub crossing panels. The settlement was up to two inches, with extensive spalling.
The Solution
CJGeo’s crew installed supplemental bolts due to replace the OEM center panel anchors, and then grouted the crossing in the mid-day window, without disruption to any stakeholder. The structural polymer grouting work took less than a day onsite. The work was done between the morning and evening commuter trains, but multiple freight trains used the crossing during the repair.
CJGrout 48NHL was the grout of choice. CJGrout 48NHL is formulated specifically for high, dynamic loading environments, such as rail crossings, and airfields. It provides superior bearing capacity, excellent resiliency to dynamic loads, and is great for correcting differential settlement between panels. Because it is relatively low mobility, CJGrout 48NHL is unlikely to affect adjacent pavement.
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Light Rail Tub Crossing Repair
THE JOB
A suburban grade double-crossing was rebuilt to address poor drainage infrastructure in the area. This included installing two different culverts adjacent to the crossing panels, and then resetting all of the panels which had to be removed for the culvert installation. During routine track inspections, the panels showed signs of deflection up to one inch with rail traffic. The system’s track division was concerned that pumping of the crossing panels would lead to destabilization of the base, and settlement. At the lower elevation end of the crossing, there was extensive evidence of sub-base material being pumped out from under the crossing within two weeks of the crossing reconstruction. 368 track feet were affected.
THE CHALLENGE
Work had to be completed during non-revenue hours, between 0200 & 0430 over two nights. There was also a high probability of the voids below the panels being waterlogged.
THE SOLUTION
High-density polyurethane grouting to stabilize the grade crossing panels. Specially-formulated hydro-insensitive void filling (high-mobility) grout was proposed in order to ensure complete filling of voids below the panels, whether waterlogged or dry.
CJGeo successfully stabilized the crossing during the two-night work period.
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Railroad Sinkhole Stabilization
The Job
This railroad sinkhole stabilization project is located in Martinsburg, West Virginia. During the installation of a 42″ jack & bore casing below a three-track Class 1 railroad, ballast started showing in the spoils. Soon afterward a sinkhole appeared between tracks 2 & 3, 15 feet above the casing. The jack & bore installation was stopped, and the contractor reached out CJGeo requesting an emergency mobilization.
The Challenge
CJGeo had to mobilize with very little notice, and work had to be performed adjacent to an operational track.
The Solution
CJGeo mobilized two polyurethane compaction grouting crews, who were on the road in less than an hour. Within four hours of the sinkhole formation, CJGeo was onsite with more than 250CY of material placement capacity.
CJGeo successfully grouted the sinkhole, using CJGrout 20SDB. Rail traffic continued on adjacent tracks, and the face of the bore was restored, allowing the jack & bore operation to safely restart. CJGeo performed this repair using a polyurethane grout with an elastic modulus similar to the existing soil in order to prevent creating a hard spot in the rail. CJGrout 20SDB was the best fit grout for railroad sinkhole stabilization project because:
- it cures to 95% strength within 15 minutes
- doesn’t impede auger boring
- is highly mobile, so will pass through ballast easily
- doesn’t have lifting capacity, so wouldn’t move the adjacent tracks
- is formulated for bulk placements without charring
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1 Mile 36″ Waterline Abandonment
THE JOB
CSX crews were surfacing the mainline track in Baltimore when the tamping equipment struck an object immediately below the ties. Investigation revealed that it was a manhole associated with nearly 6000LF of 36″ water main primarily running immediately below the tracks. The municipality relocated the waterline. Next, they had to fill the pipe from just two intermediate points. There were three sections of pipe; 1200LF, 1600LF & 2900LF. Various potential solutions for the watermain abandonment included:
- threading sacrificial tubing and grouting on the way out, and
- pumping flowable fill from the manholes,
However, none were economical or could guarantee a pipe abandonment below the railroad.
THE CHALLENGE
The project designer, OBG, identified cellular concrete as a potential solution to the problem and reached out to CJGeo to determine its feasibility. CJGeo confirmed the appropriateness of cellular concrete and set out to create a grouting plan. Coordination between the utility contractor and slurry provider (the site was too small to set up a batch plant) was crucial to ensure that the runs of pipe were all successfully filled in a single shot each. With train frequencies of 3-4 per hour, if the operation didn’t work and the pipes were only partially filled, there was no opportunity to create intermediate access points to finish grouting a section of pipe.
Based on the required bearing capacity and production requirements, CJGeo proposed 22lb/cuft CJFill-Ultra Lightweight cellular concrete for abandonment. With a 25psi break strength at 28 days, the mix provided the required strength, met the CSX utility occupancy standard for abandonment, and maximized expansion in order to ensure the longest run, which required nearly 1000CY of the finished product, could be grouting in a single shot.
THE SOLUTION
CJGeo mobilized a 150CY/hour cellular concrete crew to the site and performed the two shorter runs the first week. The project was broken into two different weeks due to the criticality of ensuring the longest run was filled completely without issue. The first two runs allowed CJGeo, the GC, railway flaggers, railway operations, and the slurry provider the opportunity to work out any kinks in operations during the lower risk placements.
The following Tuesday, starting at 0600, Chaney Enterprises delivered the first of 24 loads of slurry. Overall, the work took three days. CJGeo generated & pumped a total of 1710 cubic yards of cellular concrete to successfully complete the waterline abandonment.
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Railway Grade Crossing Repair
THE JOB
112 track feet of crossing panels settled, and needed grade crossing repair. This caused the adjacent asphalt pavement to fail. The crossing ran diagonally across the highway. The road was graded so that the crossing was the primary flow path for surface water.
The crossing had already been replaced twice. The last replacement used flowable fill as the base material. The crossing panels experienced approximately 1 inch of deflection with highway traffic. There were also 4-inch voids below the panels.
With highway traffic from heavily-loaded vehicles, the crossing deflected enough to squirt water three to four feet in the air. This water pumping action actively pumped the subbase material from under the crossing.
THE CHALLENGE
The repair had to allow immediate vehicular traffic to facilitate a single-lane closure that was flipped halfway through the repair. The repair also had to allow for immediate resumption of rail traffic. The crossing served a sand mine. so the repair was designed around high service loads for heavy haul rail traffic.
THE SOLUTION
High-density polyurethane grouting using CJGrout 48NHL for this grade crossing repair. CJGrout 48NHL is designed specifically for rail and airfield grouting work.
CJGeo modular grade crossing repair crew filled the voids and corrected settlement in less than a day. Asphalt patching was done concurrently with polyurethane injection. The entire repair took less than one day. The roadway and rail opened up immediately after the repair.
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Urban Grade Crossing
THE JOB
32 track feet of grade crossing panels settled. This caused the adjacent asphalt pavement to fail and caused tripping hazards at the adjacent pedestrian sidewalk. The grading in the area was relatively good, however, the adjacent ballast was fouled, which caused water to accumulate under the crossing panels and wash out the sandy subbase material. The crossing had been replaced recently. Due to the urban, primarily passenger automobile traffic, there was a little deflection of the crossing panels from highway traffic. However, there were up to four inches of deflection from rail traffic loading.
The deflection from rail traffic loading caused the top edges of adjacent panels to be in compression with each other. This caused extensive spalling of the surface, which affected two of the panels. While not a functional problem for panel integrity, the spalled areas were within the sidewalk portion of the crossings and therefore posed tripping hazards.
THE CHALLENGE
The repair had to allow immediate vehicular traffic to facilitate a single-lane closure. The repair also had to allow for immediate resumption of rail traffic. The crossing served as a sand mine, so the settlement correction repair was designed around high service loads for heavy haul rail traffic.
Due to the scheduling constraints of the railroad, the repair method had to tolerate the potential for rail traffic during the repair.
THE SOLUTION
High-density polyurethane grouting to stabilize and lift the affected modular grade crossing panels, using CJGrout 48NHL.
Epoxy-augmented patching of the spalled areas to restore a smooth walkway for pedestrians.
CJGeo modular grade crossing repair crew filled the voids and corrected settlement in less than a day. Asphalt patching was done concurrently with polyurethane injection. The entire repair took less than two hours. The roadway and rail opened up immediately after the repair. Traffic control was done to accommodate pedestrians and roadway traffic.
Two trains passed through the crossing over the panels being repaired during the repair. This did not affect the integrity of the repair.
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Warehouse Floor Lifting
THE JOB
25,000 square feet of the industrial floor at a military facility settled up to 4 inches and was affected by sub-slab voids. This warehouse floor lifting project also included 250 track feet of embedded rail, which was set in an independent, thickened slab section. The building had been used for warehousing but was being transitioned to light manufacturing/maintenance.
There were extensive voids below the floor. The voids were located with GPR, and confirmed with cores. Because the floor had cracked extensively as it settled, the designer called for a 4″ un-bonded overlay after stabilization.
THE CHALLENGE
The proposed repair method had to provide adequate bearing capacity for manufacturing and ensure complete void filling and stabilization.
THE SOLUTION
CJGeo provided a value engineering proposal to use geotechnical polyurethane instead of cementitious grout. The VE proposal was based on the following:
- lower unit weight, so less likelihood of causing additional settlement
- adequate strength to ensure uniform load transfer to the underlying soils
- simplified logistics into a secure facility (all material delivered in just two truckloads)
The specified grout had an in-place density exceeding 115 pounds per cubic foot. The proposed polyurethane grout, CJGrout 40NDV, has a constrained density of 5.5PCF, yet a bearing capacity exceeding 12KSF.
CJGeo mobilized three polyurethane grouting crews to the facility, with a combined pumping capacity exceeding 5,000 pounds per hour. CJGeo crews injected the CJGrout 40NDV through nearly 2,000 dime-size holes drilled in the slab to complete this concrete lifting project.
The cutoff criteria for void filling was cross-hole communication or 0.1 inches of lift. The settled areas of floor raised an average of three inches. The embedded track area raised up to four inches.
It took CJGeo fewer than 10 days to complete this warehouse floor lifting job. Because the material cures to 95% within a few minutes, the overlay preparation crew worked a day behind the polyurethane grouting crews.
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