Engineer’s Corner: Innovation in the Shoring Industry

BY Steve Barnhardt


It starts with what’s perceived as a great idea to accomplish things better, faster, and or safer. It always seems like a no-brainer to adopt great ideas and improve how things are done in hindsight. Inventors and entrepreneurs invest huge sums of time and money into developing and refining these ideas.  Once the inventor or entrepreneur is satisfied with the concept, the promotion becomes critical.  There are many reasons why innovation may catch on, while others may fail and for this reason, it’s important to have a thorough understanding of the factors that impact the successful promotion and adoption of the idea.

Shoring systems have evolved from open-cut and timber sheeting hundreds of years ago to the diverse set of steel and aluminum shoring equipment available today. Along the way, and mostly since the end of WWII, there have been some major innovations that impacted the industry. Aluminum hydraulic shores, steel shoring shields, steel trench plates, and slide rails are a few. The adoption of the OSHA Subpart P-Excavation Standard in 1990 also had a major impact on innovation due to the results-based nature versus the prescribed requirements it contained. The standard effectively addressed the growing safety concerns regarding the excavation industry, leaving the industry to determine how to more safely and effectively complete work complying with the standard.

Safety as a driver of innovation
Within the shoring industry, one of the underlying drivers of innovation is safety. For contractors to legally work in the excavation industry there are minimum standards of safety that must be adhered to or the contractor is subject to increased bodily injury and or death, damage to property, costly fines, and lawsuits, all of which may eventually put a company out of business.  The current safety culture dictates that there is always a methodology or device that can prevent an accident. Accidents lead to litigation that leads to legislation that leads to project requirements for the use of accident prevention equipment. As safety devices are developed in response to accidents and they become available on the market they quickly become standard of the industry.

Here is a good example of how this dynamic works. The use of, ramps, bridges, ladder access platforms, and handrails to access shoring shields and pit shoring systems has evolved from optional to a requirement. These devices were first built on the job by carpenters to prevent falls. Next, they became targets for OSHA inspectors to inspect and issue citations for not meeting design requirements. Splinters, cuts, accidents related to constructing them, lack of load rating and safe use notification, and cost of constructing and removing or relocating led to the development of manufactured steel and aluminum shoring access devices for rental or sale. Today even if it is not a contract or OSHA requirement safe access and fall protection devices have become a necessary part of the shoring system. If a serious accident occurs without commercially available safety equipment on the job the contractor may have a lawyer making the case that it was available and he or she did not want to spend the money or have proper concern for the safety of their employees.  Access and fall protection should always be part of the thought process when developing a shoring system.

Innovations related to trends in the underground construction industry
Shoring work is a subset of underground excavation work. Changing excavation equipment over the years has given rise to changes in shoring methods. For hundreds of years timber shoring systems developed for use in coal mines and hand-dug pipeline systems were the only shoring types available. Straight trees were driven for bearing piles and timber planks were driven as sheet piles. Steel shoring consisted of screw jacks. After WWII small backhoes and large excavators were developed for excavation but were also mobile enough and strong enough to move and set shoring equipment which resulted in the use of hydraulic aluminum shores and the proliferation of steel shoring shields. The 1980s and 1990s saw the introduction and adoption of smaller lighter, stronger, and more fuel-efficient excavation equipment. As a result aluminum shoring shields were developed as the steel shields were too heavy to lift with these machines.

Shoring systems that changed the industry
Slide-rail shoring systems were first developed in Europe. There was an unmet demand for a shoring system that had tight sheeting as opposed to the conventional dig the excavation first and setting the shoring system after which dominated the industry. In Europe, very old historical buildings with narrow streets were the challenge. Slide-rail was a major shoring system innovation because it was the first dig and push system that was designed specifically for the purpose of proactive soil support. Generally speaking, the poorer the soil conditions, the better the slide rail system performed. Before the slide rails system, contractors were trying to provide a similar function by digging and setting systems, like trench shields, with plates driven behind the walls. Until the development of slide rail, the only real option was sheet pile systems that required pile driving with the associated vibrations that can damage surrounding buildings and underground facilities. These slide rail shoring systems were first imported into the United States in the early 1980s in New York and Louisiana. The system was perfect for the poorer soil conditions, usually soft silts and clays, common along the East Coast and Louisiana. From this initial footprint, it took about 15 years for the system to gain widespread adoption and to begin to be utilized along the Western Coast, interior states, and Canada.  Major aspects of this innovation were:

  • Slide rail filled the gap in pricing between trench shields and sheet piling. At the time the gap was significant, the cost of a sheet piling system was in the range of 3 to 5 times the cost of shield systems.
  • Vibration damage concerns associated with sheet piling could be removed
  • Slide rail could be installed and dug with a contractor’s own crew and equipment in most cases. The need for specialized sheet pile driving crews and equipment could be removed.
  • Where trench shields and related dig and push adaptations become cost-prohibitive or impractical to construct, slide rail systems became a viable alternative.

The slide rail market has been growing steadily since it came to the North American market and has been a major game changer within the industry.

Steel Plates
Steel plate trench covers have been used since the late 1800s, however, in the 1980s the covers changed the nature of the pipeline construction operation. At that time 1-in and 1.5-in thick steel plates became common rental items for shoring equipment rental providers. This was the beginning of the end for the open barricaded trench in the street. Prior to this at the end of the day barricades with oil lamps, and later battery and solar lamps, were put up and taken down again in the morning. Contracts typically allowed a certain number of feet of trench left open at the end of the day.  Accidents from cars and bicycles running into open trenches were considered commonplace and hard to prevent.  Another issue was children and animals getting into open un-shored trenches.

Today when trenches and open pits in the street are not being worked in, it is standard practice to completely cover them. The change impacted the nature of the excavation operation. Prior to plated excavations the excavator was left at one end of the trench and the loader at the other end to prevent vehicles from running into the end of the trench. Barricades were strung along the sides of the trench.  The next day the crew simply picked up where it left off, excavating and laying pipe. Today the excavator, loader, and barricades are parked away from the excavation, usually in a fenced construction yard. The first operation of the day is typically to remove and store the street plates until they are reset at the end of the day.  The plate pick-up and lay-down operation has taken about two hours away from the daily production work.  At the end of every day, there is a complete clean up and street sweeping operation with the street then returned to the public to resume normal activities. Accidents due to after-hours public incursion into the work zone have been practically eliminated.  Additionally, plates allow utility potholing to be left open until production work progresses through them.  Backfill, paving, and re-excavating around previously potholed lines was eliminated. Something that was seen at the time as a productivity inhibitor can be seen today as an extremely safety-effective and cost-effective change.  This innovation just happened, it was not planned to have the impact it had, one thing led to another.

Major reasons to reject innovation
Contractors know that any type of shoring system has a learning curve. Once a crew knows how to install a timber shoring system it is going to take time and money to have them learn how to use hydraulic shores in place of the timber system. A contractor that knows how to dig and lay pipe in bad ground with a shoring shield and plates pushed down the sides would have to retrain its crew to install and successfully use slide rail. With the experienced crew, the contractor knows exactly how much it costs him to lay pipe with the current shoring system. Even if the contractor makes less money with the current system it has less risk, as the contractor knows for certain that it can do the job.

New shoring systems also present problems for the owners and engineers reviewing the shoring system. Slide rail is a tight sheeting shoring system but when it was presented as an alternative to sheet piling and pile and lagging systems it was at first rejected. It took several years to get that system approved as an alternative; however today it is accepted. Until the point at which the slide rail system had been in the ground long enough and contractors and engineers understood how it worked and that it did what it promised to do the system did not take hold. Today the slide rail system is an accepted alternative to piling systems and is used extensively throughout the United States and Canada.

The idea that “this is the way we have always done so why should we change” could be one explanation for why hydraulic shores on the West Coast are always supplied with the plywood attached to them and in the remaining majority of the United States the plywood is delivered separately from the shores and set in the trench ahead of the hydraulic shore.

In regions like Boston, New York, and Chicago timber shoring is prevalent because unions fought to retain the carpenter and laborer jobs that came with it. Also, the fact that it has been learned and used the same way since the early 1800s has kept it a staple of the industry in those areas while most other areas have a high preference for manufactured shoring systems.

The innovative path from conception to prototype, to revision, to patenting and protecting the patent, to developing market awareness, to distribution is long and expensive, extending a typical return on investment out 5 to 10 years or more.

These types of pushback have a major impact on innovation within the industry. 

Future shoring innovations
At National Trench Safety, we are committed to pursuing and developing these innovations for our industry. These innovations help contractors become more efficient and most importantly to help reduce worker injuries and deaths on construction sites.  We introduced a lightweight aluminum trench shield with very formidable depth ratings last year and we’re in the process of evaluating new potential systems and technologies for the near future.  A couple of the projects we are working on include:

  • Technology that will bring safety and shoring system information faster and more efficiently to the individuals in the field that are using it at the time.
  • Heavy duty hydraulic wale systems that are stronger than welded steel wale systems that will save time, labor costs, and wasted cut up steel beams.
  • Load sensing equipment that will in real time tell us the soil loading on our shoring equipment leading to more accurate soil load engineering solutions and less overkill and cost in the resulting shoring solution.


DISCLAIMER: the information contained in this article is provided for general and illustrative purposes only and is not to be considered Site Specific and or designated engineering for any project or work zone, nor is it to be used or considered to be tabulated data, technical data, advice and or counsel to be used on any job site.  Each project is different and is the responsibility of the employer’s designated Competent Person to make decisions on what systems and methods may be used in compliance with federal and local regulations, manufacturers tabulated data, engineered drawings, and other plans.




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