To this day, our nation’s railroads provide the most efficient transportation for bulk commodities, industrial materials, chemicals, and more. To an uninformed consumer, they exist only to stop traffic on the morning commute, but truthfully, they operate in the background as the backbone of American commerce.
URETEK Deep Injection (UDI) is the rapid, economical solution for repair and maintenance of the railroads that make American commerce possible. The safe and efficient transportation of goods and people from coast to coast is a serious matter that requires reliable maintenance and repair solutions for railroad roadways (or right-of-way).
URETEK Deep Injection is unique in assisting the rail industry in maintaining commitments to freight customers and public safety. This ability is demonstrated in several ways.
- URETEK Deep Injection has the unique capacity to strengthen nearly all soil types. UDI improves soils by permeation, compaction, and expansion webbing through weak strata.
- Over 100,000 successful soil improvement projects across the globe in many soil conditions.
- Extensive laboratory testing on treated soil specimens
- Successful projects and verification testing in rail applications. A test with the University of Wisconsin has confirmed a 90% increase in track modulus and a trial with AAR on a site that required added ballast and releveling every 5 MGT resulted in no maintenance or track deflection after the monitoring ended in 2019 with 455 MGT.
- URETEK production rigs are equipped with portable and robust geotechnical testing equipment. This allows quick and noninvasive subgrade analysis to be conducted on-site without mobilizing or engaging a geotechnical consultant.
- URETEK Deep Injection installation is a quick and agile process. URETEK operations can be mobilized quickly and work can begin immediately. If there is access adjacent to the railway for a construction staging area, there is no need to close the subject track. URETEK operation crews can demobilize from the ROW with 30 minutes notice and remobilize when the track is clear.
- URETEK material obtains 90% strength in 15 minutes, which means traffic can resume immediately after the installation is complete.
These qualities add up to an accelerated repair timeline and confidence of minimal to no maintenance required on a treated area in the future. A potential accelerated project timeline could proceed as follows.
Day 1 – Railway maintenance staff identify a problem area that must be brought back to level and it is a location that has required repeated maintenance indicating a problem with the subgrade.
Day 1 – Railway operator contacts and engages URETEK to provide a repair solution.
Day 2 – URETEK operations crews begin mobilization. URETEK engineering reviews available- site information provided by the client as well as topographic and soil map information available online.
Day 3 – URETEK arrives on site. URETEK operation crews perform geotechnical testing to assess the subgrade. Geotechnical information is sent to URETEK engineering and an installation plan is created to treat the weak subgrade. URETEK operations begin installation under the direction of engineering.
Installation will be completed as quickly as possible depending on project scope. Demobilization will happen immediately after project completion. Construction is completed and with the subgrade repaired no further maintenance should be required at the treated site.
For railway subgrade repair, track stabilization, and rail realignment UDI offers fast repair and almost immediate improvement in track integrity and geometry in much less time for fractions of the price.
Common Causes of Railway Deterioration and Infrastructure Failure
Both natural and man-made causes can lead to weak soils beneath railroad tracks. The original soil composition may have included loosely packed materials that were not packed well before construction, or nearby drilling or excavation may have resulted in compromised subgrade strength. Regardless of the cause, weak soils generally result in subsidence, which often leads to the formation of voids beneath the surface, below the ballast and in the subgrade. Left unchecked, subsidence can harm railway systems. Symptoms of weak soils, in this case, include settlement, slope failures, low modulus track, compromised rail substructure, and visible vertical and horizontal track misalignment.
When subgrade or roadway defects necessitate a decrease in train speed, handling issues increase, and fuel economy decreases. Already compromised roadbed become more susceptible to drainage issues. Compromised areas remaining wet for prolonged periods (whether rain or snow) or flooding can increase erosion or speed failure of the damaged roadway. Such cases can result in a catastrophic train derailment, a massive expense for rail system operators, and a serious matter of public safety.
The most common causes of railway accidents are broken rails, faulty welding, faulty track geometry, and buckled track. Whereas the most common problems over time may include compromised rail substructure, subsurface voids, and sloping or inconsistent ground levels that also result in poor transport conditions and lead to expensive vehicle maintenance issues.
Locating the Problem Area
URETEK routinely begins each new project with on-site Dynamic Cone Penetrometer (DCP) testing, which is used to measure the base soil layers’ comparative strength beneath rail roadways, bridge approach/departure slabs, and tracks. This information is used to determine exact locations and levels for the injection of the polymer material used to strengthen and densify problem soil strata.
Repairing the Problem Area
Once the problem areas have been identified, URETEK crews develop a site-specific injection plan to address the issues. After determining factors including differentials in elevation, erosion, and water damage, the compromised section of track is identified, and URETEK technicians drill through a railbed in accordance with a predetermined grid pattern. Injections are made directly through the railbed, and laser level monitoring equipment is utilized to detect vertical movement.
The injection process is repeated, using a gridwork of hole locations until the entire area is sufficiently stabilized by the polymer. If the road crossing also needs to be leveled or raised, this is achieved through further monitored injections.
Monitoring the Repair Process
On subsequent scheduled appointments, URETEK crews return to complete work on any additional track that may suffer from the same issues. The polymer expansion reaches 90 percent of its full compressive and tensile strength within approximately 15 minutes. Because the polymer material is exceptionally light, any additional overburden weight is kept to a minimum. The properties of URETEK’s polymer material is carefully matched to typical base material compressive strength characteristics.
URETEK Deep Injection® (UDI) is Ideal for the Following Railroad Applications
UDI involves the injection of structural polymer into base and subgrade soils to increase its load-bearing capacity. This is achieved by injecting the polymer through small holes drilled directly through the soil substructure to depths determined by site-specific analysis. URETEK’s proprietary high-density polyurethane foam (HDPF) polymer material flows easily into voids and weak zones within the soil mass below. Then, through a controlled chemical reaction, the expanding polymer compacts surrounding soils, increasing their load-bearing capacity. The composite material quickly cures into a strong, dimensionally stable, environmentally inert, non-toxic, and water-resistant geo-material that provides years of reliable service.
There are four key applications where UDI provides a significant advantage over more traditional methods in solving complex subsurface lifting and soil densification problems:
- Void Filling – When weather conditions produce rain, snow, or severe temperature shifts, expanses such as fissures and water pockets can be created. Over time, these expanses form voids just below the roadway surface. These voids can result in settlement, sinkholes, or slope failure, which can destabilize the railroad roadway. UDI is very effective in addressing these types of voids. URETEK’s expansive, hydro-insensitive polymer material drives out any standing water and aggressively fills voids. It also densifies the soil and prevents the expansion and formation of new voids in the future.
- Stabilization – By correcting soil defects, strengthening weak soils, and void filling, UDI stabilizes soil and prevents pumping or further differential settlement of these assets. UDI effectively fills, compacts, and stabilizes subgrade soils beneath the track roadway surface and seals the area from any further water intrusion which could contribute to degradation. It is the only process that combines the benefits of sealing, stabilizing, and asset protection with rapid curing time; this allows the project area to be quickly repaired and returned to service.
- Lifting – UDI is quickly and economically applied to solving the subgrade soil densification, track lifting, and track geometry (realignment). The expansive, hydro-insensitive properties of URETEK 486 Star® polymer ensure those settlement problems are properly corrected. Since the material is injected in layers, the amount of lifting can be controlled to within one-tenth of an inch, which assures accurate lifting profiles.
The UDI Advantage
- Fast – UDI requires no excavation, and projects can often be completed in hours or days. Traditional repair methods often involve excavation, and the time required for project completion can be weeks.
- Effective – URETEK’s 486 Star® polymer material has been used to successfully complete over 100,000 projects nationwide. The lightweight, expansive geo-polymer material not only realigns roadways but also addresses the problem at the source – weak soil composition – giving customers a long-lasting solution.
- Economical – The repair process is priced consistently below alternative repair methods, and implementing repairs now significantly reduces further repair costs down the road.
- Minimally Disruptive – Unlike other repair methods, UDI is minimally disruptive and requires no excavation.
- Durable – URETEK’s 486 Star® polymer is specially formulated for stability and strength, even in the harshest environments. Our polymer is hydro-insensitive, and UDI is warranted against loss of dimensional stability or deterioration.
- Safe – Liability risk is significantly reduced with UDI due to an inherently safer working environment without deep excavation or heavy equipment. The process and material are eco-friendly and meet today’s high environmental standards.
- Tested – Both the University of Wisconsin, Madison and the Transportation Technology Center, Inc. (TTCI) have conducted extensive experiments using UDI and HDPP on rail roadways proving usefulness and acceptability.
Rail Systems Depend on UDI
For track maintenance and maintenance-of-way, time is truly money. For example, should repairs require the shutdown of a main track or branch line, traffic must be either diverted or stopped until the repair is complete. When rail traffic comes to a halt, associated costs in man-hours, re-crews, and fuel consumption can greatly affect a carrier’s bottom line.
The same is true for portions of track where erosion or water intrusion has weakened sub-soils resulting in settlement, slope failure, or water pockets. Slowing train speeds due to subgrade or roadway defects negatively affects train handling, fuel economy, and the bottom line.
URETEK can restore the integrity of rail beds, repair crossings, and stabilize drainage systems (e.g. culverts, drains, scouring) and bridge abutments/approaches/departures surfaces with no requirement to take tracks out of service for extended periods. Our ability to clear work areas, allow train traffic to pass, then return to work immediately keeps operations running with minimal interruption.
Trusted Vendor for Railroad Maintenance Programs
Beginning in 1988, with the introduction of URETEK Deep Injection®, our trusted soil stabilization method has been relied upon by city, state, and DOD officials across the country. In every climate, they depend on UDI to stabilize soils, fill voids, and most importantly, maintain and extend the life of their essential railroad assets.
When we arrive, our crews get right to work on a site-specific repair or maintenance solution that quickly mitigates weak soil issues and extends the reliable working life of important assets. Best of all, our zero-excavation solution means the work is completed in days, not weeks or months. When the job involves stabilizing subgrade soils and restoring critical rail systems to their optimal functional state, nobody does it better or faster than URETEK.
Contact URETEK today to learn more about our speedy maintenance and repair solutions that keep budgets in line while assuring many more years of reliable service from essential roadways.