Jack & Bore Under Railroad

The Jack and Bore offers the best way to install casings and pipes under existing road grades. Rail Roads and highways are two examples of roadbeds that will suffer the least amount of disturbance when pipelines or other infrastructure needs to be installed beneath road or rail. The Jack and Bore maintains the integrity of the roadbed during installation. The following case study illustrates this point.

Midwestern Contractors was awarded a project that required cutting out a 220’ section of 16” pipeline that crossed under four railroad tracks. The carrier pipe was inside a 150’ long 20” casing.

After laying out the work area and locating the pipeline crews were dispatched to both sides of the tracks. Crane mats were laid down to protect the surface and create a stable work area for equipment movement, material storage and fabrication.

After this was complete excavation began on the entry and exit pits. The entry pit was approximately 80’ long to accommodate installation of a full 40’ length of new pipe. The exit pit only had to be 20’ long and wide enough to allow for a cut on the existing pipeline with room for the offset to the new replacement section. Each excavation was over 12’ deep and this required the installation of sheet piling, reinforced with whalers and hydraulic spreaders to hold the trench, and provide a safe workspace. It should be noted that the entry pit also was wide enough to expose the existing pipeline. This is shown in the photographs.

Once the floor of the excavation was layered with compacted stone the boring machine and track was lowered in, aligned and work could begin. The first phase of the operation was to install the casing. All equipment was set up outside of the railroad right of way. However, the bore would penetrate the highly compacted roadbed. The total weight of the Barbco 36/48-500 boring machine, track and casing pusher came in at 14,000 lbs. This machine could exert 502,000 lbs. of continuous thrust, and up to 583,000 lbs. of thrust intermittently.

The 20” dummy casing was installed first, and it was installed in 20’ sections. The shorter length provided more rigidity as the machine bored through the compacted material. Each segment was welded to the next and pushed into the bore for the total distance of 160’. After the dummy casing was installed, the next task was to install the ARO coated, final install, casing pipe. After installation of the ARO coated casing pipe, the carrier pipe was installed in the casing.

The sections of carrier pipe were prepared in the fabrication area. All spacers were installed and then backed up by clock spring wraps embedded in epoxy. This technique prevents the spacers from moving as the carrier pipe is pushed into the casing. As each section was pushed into the casing the next 40’ section was lowered in, clamped, and welded. All welds were X-rayed, and then coated. This process was repeated for the entire 160’ length.

The existing pipeline was now taken out of service and drained. Cuts were made on the existing pipe to remove 15’ on each end. This allowed enough space for the offsets to be welded in. Before tie-in, the new section, along with the offsets was hydrostatically tested. After this test the water was pumped out, weld caps cut off the offsets and the new section aligned and clamped to the existing pipeline. Once aligned the tie-in welds were done, X-rayed, and coated. The pipeline was then put into service.

The existing pipe, still in the old casing, was now extracted. This pipe was pulled out as far as possible, then cut and hoisted out. Plates were welded to the old casing, still in place, and grout was pumped in to fill it completely.

With grouting complete the exposed pipeline could be sand padded and backfilled. As backfilling progressed the hydraulic spreaders and whalers could be removed. Next the sheet piling was removed.

With backfilling complete, material and equipment were removed from the site. All matting was removed, and surface restoration was completed.

The great benefit of utilizing a Jack and Bore in this circumstance is the preservation of the compacted roadbed during the installation of the new pipeline.

Midwestern Contractors (MWC) installs and maintains oil and gas pipelines, stations, gas injection fields, meter and regulation stations as well as providing integrity services. MWC will deliver turnkey projects for mid-stream, distribution, renewable natural gas (RNG) and liquid pipelines and facilities. If you would like to discuss your project with one of our PM’s, please click on “Request a Project” or call Mike Purpura at 630-936-3282.