Maryland leaders hope that new double-stack container provider will assist develop the Port of Baltimore, and the native financial system at the side of it. However for shipment sure to locations within the Northeast, double-stack container trains should loop masses of miles west via Ohio sooner than turning again east as a result of a couple of ultimate obstructions on CSX Corp.’s I-95 rail hall, which don’t supply sufficient clearance for double-stack provider to cross.
Now CSX is within the procedure of constructing the infrastructure enhancements vital to open up that hall from Baltimore to Philadelphia for double-stack provider. The most important ultimate obstruction is the railroad’s 130-year-old Howard Side road Tunnel, which is set 2 feet wanting the clearance had to run double-stacked teach automobiles via it.
To handle the problem, CSX employed Skanska-Fay JV as its innovative design-build contractor by way of a $242-million contract to extend the clearance from top-of-rail to 21 feet. The JV labored with lead dressmaker Hatch and native company WRA to advance the design. Participants of the mission workforce say the versatility that the innovative design-build style supplies has been very important for optimizing their paintings and assembly the landlord’s wishes.
“This activity is lovely supreme for innovative design-build as a result of there’s most of these other choices, says Mike Goetz, mission supervisor at Skanska. “It’s now not like we have now something to construct, and there’s just one solution to do it. There’s many various tactics to do that and reach CSX’s function.”
They regarded as choices comparable to notching the crown in some spaces and notching the invert or each in others. However as they took core samples of the brick to test if there can be sufficient lessons of brick left after notching, they discovered an excessive amount of variation, says Tom Costabile, Skanska’s building supervisor at the mission.
“That you must take a core proper right here, after which 10 feet away you’d have a unique thickness, so it was once arduous to have agenda sure bet there,” he says. “There’s numerous chance. So we proposed doing a complete invert substitute, which supplies the landlord a pleasing uniform invert as smartly.”
Plans additionally developed according to deliberate outages. The workforce scrapped an early plan to paintings right through weekend and in a single day tunnel closures, which might have concerned time and again mobilizing and demobilizing to finish paintings in past due 2027. In the end, CSX agreed to a complete shutdown of the tunnel beginning in February and working via October, with really extensive finishing touch now anticipated this autumn—“massive financial savings there,” Costabile says.
With such a lot of enhancements to the plan during design and building, the workforce tailored “support, adapt and triumph over” as their slogan for the mission.
“We had numerous time forward of this mission to do making plans, after which after we in truth were given boots at the floor, numerous that making plans needed to be changed as we discovered what labored and what didn’t paintings,” Costabile says. “We proceed to conform to nowadays. Nearly each week we’re arising with one thing to do higher, so our cycle instances proceed to lower and we’re going to proceed bettering most likely till the remaining day of the mission. It’s labored out really well.”
1895 Tunnel
The Howard Side road Tunnel is set 8,700 feet lengthy, working below downtown Baltimore from Camden Yards within the south to the previous Mt. Royal teach station within the Bolton Hill group within the north. It was once in the beginning finished for the Baltimore and Ohio Railroad in 1895. Many of the Howard Side road Tunnel is mined, nevertheless it additionally has a cut-and-cover segment and a concrete field segment added within the Eighties to deal with building of a freeway.
The mission additionally covers observe paintings extending about 700 feet at the south facet and a couple of,300 feet at the north facet, together with the 265-ft-long Mt. Royal Tunnel.
Early paintings integrated accumulating LiDAR scans, application preparation and organising drainage volumes, for the reason that mission’s scope comprises bettering drainage within the tunnel. It’s a free-draining tunnel, designed to permit water to leak in, however the workforce wanted to make sure the water getting into the tunnel has someplace to head so it doesn’t finally end up within the observe mattress and smash down the ballast. About 550 gal of water comes during the tunnel in step with minute. They ended up with a couple of drains working alongside the partitions and two extra trough drains beneath the tracks. The water discharges at Camden Side road.
New Invert
As soon as whole, the brand new tunnel invert will consist of one,188 precast invert slab (PCIS) segments. Each and every PCIS phase is 6 feet lengthy, with a flat backside and two recessed trough drains, and wings that arise at an perspective, measuring about 18-19 feet throughout from wing to wing, relying at the width of the tunnel at a given location. The workforce operates in cycles, putting in 3 segments at a time. Enhancements to their way and strategies—”support, adapt and triumph over”—have allowed the workforce to extend their price from two cycles in step with day to 3, Goetz says.
At the beginning of every cycle, the workforce makes use of a vacuum de-watering machine at the comfortable soil present in many of the tunnel, normally out 150 feet forward and 50 feet again. Then they demolish the present invert, excavating 21 feet forward.
The mission’s restrictions and strange stipulations required specialised apparatus, particularly because the workforce discovered hi-rail apparatus, dual-mode cars that may function on or off tracks, “is briefly provide, and it is usually notoriously unreliable,” Costabile says. For demolition, they to begin with began with a standard hydraulic hammer, however discovered it moderately inefficient. They ended up the usage of 3 remote-controlled Brokk demolition robots, together with the 2 greatest fashions the corporate has made. Costabile says they’re extraordinarily environment friendly at demolishing brick masonry like that discovered throughout the tunnel.
“They’re roughly like an endangered species of kit,” Costabile says of the bigger Brokk robots. “There don’t seem to be numerous them globally to be had.”
They then use crawler carriers to take away excavated subject material. The chassis has a rotating level, so the apparatus can also be pushed in, rotate on an axis, get loaded with subject material after which power immediately out with no need to again up or flip round. The crawlers even have low floor force as a result of the width in their tracks, in order that they don’t tear up the present invert or create a muddy mess.
The workforce wanted an excavator with numerous breakout pressure, however discovered maximum apparatus was once too massive with growth knuckles that will have hit the facet of the tunnel, and so they shouldn’t have been in a position to rotate throughout the tunnel. They discovered a Mecalac excavator with a novel multi-piece growth that permits it to paintings in surprisingly constrictive geometries, in step with Costabile. It’s a work of kit he says is in style in Europe, however arduous to search out within the U.S. It includes a sandwich coupler machine, which permits the workforce to modify out the lean rotator for a hydraulic hammer “with no need a mechanic disconnecting hoses and the whole lot,” additional boosting potency, Costabile provides.
After excavation, the workforce then compacts and prepares the subgrade with geotextile cloth and beaten stone, plus 4 leveling pads that can enhance the PCIS segments the place they meet.
To position the PCIS segments, a standard crane or gantry machine shouldn’t have labored within the tunnel, particularly with the quick paintings home windows between trains below the unique plan. So the workforce commissioned a couple of customized gantries, which Costabile calls the mission’s “crown jewels.”
Kelley Engineered Apparatus designed the gantries, which weigh about 225,000 lb. Each and every has a flat rail automobile with a 120-ft gantry rail above it, a 30-ft cantilever for shifting the segments forward of the auto and a 15-ton electrical hoist. They’re designed to be “so simple as imaginable,” Costabile says, in order that it’s simple to switch elements as wanted as it’s one of these essential piece of kit for the mission.
The workforce ordered two with an early plan of getting two headings right through quick paintings home windows between trains, however with the entire tunnel closure have opted to as an alternative use one heading, with apparatus shifting in from the east portal, close to the previous teach station, and excavated subject material going out by way of the west portal close to Camden Yards. Abingdon, Va.-based Wolf Hills Fabricators constructed the gantries.
As soon as 3 PCIS segments are in position, crews then grout beneath them via seven grout ports. Subsequent, they position rebar and urban for the prolonged wings in an effort to reestablish an inverted arch form for the invert, which transfers the 2 footers’ quite a bit.
Concrete Wishes
With paintings continuing 24/7, the workforce wishes so to position concrete at any given level on any given day, which dominated out the usage of an area ready-mix plant. However in addition they don’t have enough space for a batch plant, so the workforce got a Fiori concrete batching automobile. The workforce additionally were given tremendous sacks stuffed with bulk concrete subject material, with a customized blend designed with some components to boost up the response for the top early energy wanted for the mission. The CBV alternatives up a perfect sack, discharges it into its drum after which provides liquid after which supplies concrete proper throughout the tunnel the place it’s wanted.
“We’d like early energy in an effort to meet our agenda,” Goetz says. “We can not get started that subsequent 21 feet till that concrete is cured to a minimum of 1,000 PSI. We position the concrete, wait about an hour and we pass proper into the following cycle.”
To boost up the method additional, the workforce began the usage of shoring posts—mainly screw jacks—to undergo upon the footer on one facet and the phase at the different, permitting them to instantaneously switch the weight throughout and during the segments, so crews can advance to the following cycle immediately. As soon as the gantry passes, the workforce brings in concrete by way of hi-rail truck and so they position a extra standard blend. That modify is a part of what helped the workforce up their price to finish a 3rd cycle in an afternoon.
The overall step of the cycle is the usage of the gantry to fly a observe panel all the way down to the newly put in PCIS segments. Then the workforce advances the gantry and begins the following cycle.
The observe panels use bushes crossties, fairly than direct fixation or metal ties. That manner it’s more straightforward for CSX to switch a bit of rail, will have to it ever grow to be broken, Costabile says.
“They are able to reduce out the segment of observe that’s broken, installed observe panels that they’ve staged during their community, and get it operational once more,” he says.
The tunnel’s closure to trains is scheduled to finish in October, and really extensive finishing touch is scheduled for this 12 months. To this point, greater than 400,000 exertions hours have long past into the mission, which is greater than 80% whole.
Derek Mihaly, building director at CSX, says paintings may be advancing at the different ultimate obstructions to double-stack provider at the railroad’s core intermodal community. Across the finish of remaining 12 months, the railroad cleared a number of tasks in Philadelphia. One web page in Delaware has two bridges that want to be raised. After which in Baltimore, there are some smaller tunnels and 3 overhead bridge replacements that want to be addressed along with the soon-to-complete Howard Side road Tunnel reconstruction.
