Heavy hydraulics

Over the course of time, demand for heavy duty crawler cranes can fluctuate quite dramatically according to the demands of large construction projects. However, in recent years we’d estimate average annual demand in the range of 300–350 units worldwide. Of this we’d estimate that the established European and Japanese manufacturers contribute approximately 200 units and the Chinese and Russian manufacturers around 100–150.

The typical Japanese and particularly European cranes are of significantly higher capacity than other competitors and therefore generate substantially higher average revenues. In contrast the Chinese cranes are normally quite small, lower-capacity units with relatively-low sales prices. Consequently, the European and Japanese cranes probably constitute some 80% or more of total revenues.

In the early days the first fullyhydraulic crawler cranes were quite small machines. Sennebogen’s first fully-hydraulic crawler excavator/ crane introduced in 1969 was the 15t capacity SK 15. Powered by a 105hp diesel it was available with dragline or grabs of 600–800l capacity. The previous year PPM, then a division of the leading hydraulic excavator manufacturer Poclain, had introduced the its first fully-hydraulic crawler excavator/cranes in the shape of the 12t capacity model 12.02 available with dragline buckets of up to 700t capacity. PPM went on to sell over 400 hydraulic crawler excavator/cranes.

However, in terms of product development, throughout the 1970s, it was really Hitachi and Sumitomo that made the running. By the end of the decade these Japanese manufacturers offered fully-hydraulic crawler excavator/cranes of up to 150t capacity. Their machines, especially in the small-to-mid size classes, became immensely popular both at home in Japan but also throughout Asia, Australia and Europe. While most of these were not ‘heavy duty’ crawler cranes, all were capable of performing as draglines, grab cranes and pile drivers as well as straight lift cranes. Arguably Hitachi was the mostcommitted to fully-hydraulic cranes while Kobelco, Sumitomo, IHI and Nissha continued for some years to rely on the heavy-duty versions of their big mechanical crawler cranes for duty cycle and foundation work.

From its start in 1980, Liebherr Nenzing offered larger-sized heavy duty hydraulic crawler cranes of up to 100t capacity, while by the early 1990s the Austrian company as well as Kobelco further extended their lines with 120t–150t cranes. The field of players offering high capacity fullyhydraulic heavy-duty crawler cranes was broadened in 1993 with IHI’s introduction of its 100t capacity DHC 1000. Powered by a 550hp (480kW) Cat turbo-diesel and with 20t free-fall winches this machine had 200hp available to devote to driving piles up to 3,000mm diameter. Still, 35–80t class cranes remained the most popular worldwide. Japan remained by far the largest crawler crane market with even its fourth-largest supplier, IHI, having a domestic population of some 13,000 crawler cranes with 30–40% of these being equipped with foundation attachments.

The growing appeal of HD crawlers lay in their increased engine power, stronger line pulls and greater structural strength that facilitated higher-performance in a broader range of work including foundation, and duty cycle excavating and materials handling with grabs, and so forth. At the same time, although more expensive, these cranes remained almost as transportable and easy to operate as regular crawler cranes, thus appealing to crane rental companies as well as contractors.

It was when large infrastructure projects in South East Asia emerged in the mid-1990s that international demand for very-powerful, heavy duty crawler cranes of 100–200t capacity really took-off. In markets such as Hong Kong, where deep pile foundations were essential for building and infrastructure development on large areas of reclaimed land, these powerful cranes came into their own. Hong Kong’s largest contractor, Gammon, owned a fleet of upwards of 100 Kobelco crawler cranes but for the deep foundation work with casing oscillators the 100t–120t Liebherr cranes with their strong line pull performance that were dominant.

Crawler cranes enjoy the longest working lives of any variety of mobile crane with many machines built in the 1990s and 2000s still in service. However, ‘new’ demand for multipurpose machines, including crawler cranes, continues to be eroded as their duties are substituted by more specialised machines such as purpose-designed foundation, excavating and materials handling machine such as drilling and boring rigs, long-reach hydraulic excavators and larger-sized scrap and materials handlers. While applications such as dragline, grab dredging and highoutput material handling still require crawler cranes, over time the market has gravitated towards ever-larger and more powerful machines.

Foundation piling

It has been a long-term evolutionary process. Piling dates back centuries, but at the start of the 20th Century steam-powered piling rigs were mostly static, mounted on various forms of tripod. They achieved a measure of mobility during the 1920s, being mounted, with their leaders, on small lattice boom cranes. Technology took a big step forward with the development of the first diesel pile hammers in Germany by companies such as Menck (1936) and Delmag (1940), and in the US by McKiernen-Terry Drill Co., of Dover, NJ (later named MKT), Link- Belt-Speeder Co and others.

During the 1960s, the technology advanced rapidly, thanks in large part to the increased employment of hydraulics. Rigs were developed with long hydraulic cylinders to change the inclination angle (or rake) of the leaders and mounted on crawler cranes with their lattice boom now removed. The idea quickly gained traction, especially in Japan with all the players participating, but with Nippon Sharyo Company (Nissha) fully focused on the foundation market and for some years becoming the dominant supplier. While Nissha pioneered the three-point supported crawler piling rig, a similar rig was developed in the UK by British Steel Piling Co (BSP), which they installed on British crawler base units. In Italy a similar solution was adopted by Casagrande and FMC Link-Belt SpA. However, diesel hammers didn’t address the big issue with pile driving—their repetitive loud banging noise and the harsh vibrations that resonated through the surrounding environment.

For many years the makers of the piling and drilling equipment such as BSP, Wirth, Delmag and others had been directly involved in installing their equipment on cranes. But as demand developed for ever more-powerful and sophisticated solutions, crane manufacturers, sometimes reluctantly, became more directly involved in the installation of foundation attachments on their cranes. This was a key factor in the development of demand for heavy duty crawler cranes with increased engine and winch power, presenting a ‘cleaner’ and betterengineered solution.

Starting in the 1960s, rotary drill rigs designed for crane-mounting, first produced by companies such as Calweld and Watson in the US, added a new dimension to the role of crawler cranes in foundation applications. These frame-mounted heavy augers were pinned to the front of crawler cranes and hoist-rope supported from the boom tip. Mostly they had their own power units carried on the rig frame, but when necessary employed auxiliary power units mounted on the rear of the crane, often in place of the counterweight. While this technique gained popularity as an alternative to driving piles, predictably, around the world, favoured approaches varied. For example, in Italy traditional bored piles remained popular while in the UK CFA (Continuous Flight Augering), though not suitable for larger-sized deep piles, became the most popular technique. However, it was Japan that would fundamentally change the market.

Following 1978’s Miyagi-ken-okijishin earthquake, Japan’s Building Standards were revised, with new guidelines on the seismic design of buildings introduced in 1984. Also, by the 1990s, environmental concerns had virtually outlawed the use of diesel pile hammers in countries like Japan. In response, Japan’s crane makers such as Kobelco and Sumitomo developed purpose-designed crawler drilling rigs. Meanwhile the average size of crawler cranes used in foundation applications in Japan increased from 35–40t to 50–65t. Hitachi launched its 65t capacity KH 250HD Heavy Duty crawler cranes equipped with a rotary piling rig capable of drilling to diameters up to 3,000mm and to depths of 65m. Similarly, at that time in the US over 50% of shipments of Link-Belt’s 75t (68t) capacity LS-138H were equipped with a third drum and tough angle-chord booms.

Critically, however, it was new techniques such as vibro-piling and pile pressing rigs manufactured by companies like of Japan’s Giken and Tosa that effectively addressed the noise and vibration issues long-associated with pile driving. Significantly, on certain types of piling applications, the use of these new tools, didn’t require the constant involvement of a crane.

In Europe, German companies such as Messmann developed a line of high-frequency piling vibrators that would prove a successful marriage with Liebherr’s heavy duty crawler cranes. Piling rig manufacturers such as Soilmec evolved to add crawler cranes to their lines. However, before becoming a crane maker in its own right, Soilmec cooperated with various crane makers including Sumitomo in Japan, and sometimes even opening market opportunities for them. For example, Soilmec created demand for its casing oscillators in China and then sold these installed on LBS heavy duty hydraulic crawler cranes. Indeed, while there is a long-tradition of similarly ‘collegiate’ behavior in this industry, the well-known Finnish rig manufacturer Junttan long-since decided that they didn’t need to work with crane manufacturers and were better served by developing their own crawler carriers to provide fullyintegrated mobile piling and drilling rigs. More recently, in 2016, the Dutch Dieseko Group acquired crawler crane and piling rig manufacturer Woltman. Earlier Woltman had closely cooperated with PVE’s drilling and piling equipment manufacturing subsidiary (acquired by Dieseko in 2014), forming Woltman Piling & Drilling Rigs BV. Last year saw the first fruits of this amalgamation with the launch of the 555kW Woltman 55VR crawler piling rig equipped with the PVE 23VML vibratory hammer.

It can be confidently forecast that the world market for foundation machines will continue to expand, propelled by global urbanisation and the accompanying tremendous growth in metro and rail systems. Over the past 10–15 years, demand for purpose-designed crawler drilling and piling rigs has continued to develop at a high-rate worldwide. Larger-sized drilling and piling machines with operating weights of up to 140–150t and approximately 500kW installed diesel power have grown in popularity. These machines deliver maximum torque as high as 510kNM and are capable of drilling piles up to 3,000mm diameter and to depths of up to approximately 100m. While today these machines generally represent the upper-end of the market, in 2017 Bauer once again upped-the ante with the introduction of their top-of-theline BG 72 BT 180. Powered by a 709kW diesel, this massive machine weighs in at 236t. Equipped with twin 600kN winches, the BG 72 delivers a maximum torque of 721kNM allowing it to drill piles down to 125m depth and up to 4,600mm diameter.

Compared with lattice boom crawler cranes, the drilling and piling rigs are generally more-compact and readily transportable either complete with their mast and tools in-situ or with the masts and tools separately transported. Upon arrival on site these rigs self-erect, often with just one-man using a remote controller making them ready to work in an hour or less. While specialist foundation and bridge-building contractors purchase the majority of these machines, their transportability and ease of erection and operation have also opened up a significant rental opportunity.

Versatility still key

In discussing the role and merits of heavy duty crawler cranes, we do not mean to imply that conventional ‘standard’ crawler lift cranes are unsuitable for similar work. Obviously, many thousands of standard crawler cranes are working worldwide as grab cranes, pile drivers, and so on. However, for long-term duty cycle work and particularly heavy-duty applications, the strength and power of ‘heavy duty’ crawler cranes will deliver faster cycles, greater productivity and, critically, a much-longer, service life with less wear and tear. Their heavier structural frames and booms are designed to sustain prolonged hard work while the higher installed engine and hydraulic power obviates the need for auxiliary power units.

Even in the 1990s, crawler cranes were still being used in Europe with drop balls for demolishing old and damaged building. The swinging of a heavy ball created massive centrifugal force on the boom, leading manufacturers like Hitachi to reinforce their booms and equip their crawler cranes with special free fall winches. For similar applications the Liebherr HS 832 HD was equipped with extrawide track pads to enhance stability as well as bullet-proof glass and a steel grid over the cab. As larger hydraulic excavators with special long demolition booms emerged, the more dangerous swinging ball approach was widely discontinued.

The dominant application for HD crawler cranes is with diaphragm wall (or slurry) grabs for trenching down to depths of 50m or more. Mechanicallyoperated diaphragm wall grabs were introduced back in the 1960s and by the 1980s the technology had advanced with companies such as FMC SpA (later LBS) selling its crawler cranes with Kelly-bar mounted ‘hydraulic’ slurry grabs for projects as far afield as Cairo and Singapore. However, rope-suspended mechanical slurry wall grabs remained popular due to customer concerns over the potential for oil contamination with hydraulic grabs.

For even deeper digging depths, the hydromill has established itself as a highly efficient tool. The first large-size diaphragm wall trench cutter (or hydromill) was developed by Bauer back in 1984 with Casagrande introducing its own K3L hydromill on its 91t C 90 HD crawler crane in 1985. Since then these tools have facilitated increased wall thicknesses and greater depths using long hoses carried on vertically-mounted hose reels. By the mid-1990s, cutters able to work in extremely hard rock formations had been developed. In market terms, Bauer has led this revolution, having supplied its 300th trench cutter back in 2012. Naturally, due to the weight and power requirements of tool cutters and their hose reels, trench cutters are generally installed on larger-sized crawler cranes with massive installed engine and hydraulic power. To date the greatest depths claimed for trench cutters was achieved by Soilmec in 2012, when they tested one of their hydromills—albeit under favourable conditions—and achieved an astonishing digging depth of 250m on a crane with 900kW diesel installed.

Europe’s leading suppliers

While in a short period of time, Bauer has made a major impact on the market for heavy duty crawler cranes, Liebherr and Sennebogen remain the two most prominent European manufacturers of heavy duty crawler cranes. In recent years both companies have extended their crane lines with the introduction of their largest cranes to-date, both nominally rated 300t capacity. Sennebogen has been extraordinarily active in its new product development.

Sennebogen’s impressive new product development has been across the board capacity-wise but most recently, their line was extended with the introduction of the mid-range 70t capacity 670HD crawler excavator/ crane. Filling the gap between the popular 55t 655E and 90t 690HD the new machine is available with a choice of 261kW and 321kW Tier 4 diesel engines and a choice of pairs of 16t and 20t free fall winches. Main boom lengths of up to 56.9m are available on the new model and Sennebogen will be hoping that this can replicate the market success of its sister machines. The 655E has proven particularly popular as a dragline in markets ranging from the UK and France to as far afield as New Zealand. Most recently Karl Mossandl GmbH based in Dingolfing, northeast of Munich, acquired a new 655E equipped with 30m boom and 2.2m3 dragline bucket for canal work.

Further up the range, Sennebogen’s latest HD model is the 140t capacity 6140E mounted on one of its Starlifter crawler undercarriages offering hydraulic track width adjustment from 4.6–5.5m. The 6140E is available with a choice of 34t and 45t counterweights and either 250kN standard winches or 300kN or 350kN options. Two 6140Es complete with hydromill attacments, delivered to the Spie Fondations subsidiary of Spie Batignolles, and are hard at work on the massive Grand Rapid Express metro project in Paris.

Meanwhile Liebherr Nenzing is benefitting from its fast-expanding line of purpose-designed drilling and boring machines. These machines strongly complement Liebherr’s market-leading heavy duty crawler crane line, allowing the company to provide foundation contractors and renters with a complete product line. In addition, Liebherr has continued to place heavy emphasis on developing its own work tools. After all, these highly-sophisticated and expensive digging attachments (or tools) are fundamental to the overall performance of a machine.

One recent development was the LV 20 Vibrator and last year the company introduced its own-design fully-hydraulic slurry grabs—the HSG 5-18C and HSG 5-18L. While many manufacturers and crane users purchase their grabs from third-party manufacturers, Liebherr is a strong proponent of fully-integrated solutions. They argue that, just like every other element in a machine’s specification, there are distinct benefits in the business-end of the crane being designed and supplied by the crane maker. It makes for a more unified, efficient and integrated product package. To achieve the precision demanded, these new grabs incorporate integrated verticality recording and radio data transmission. According to project requirements, optimal use of these powerful grabs is achieved when installed on the Liebherr HS 8070HD, HS 8100HD or HS 8130HD of 70t, 100t and 130t capacity. All are equipped with synchronized winches that allow high grab weights and optimum lifting capacity. The new grabs feature hydraulic adjustable guide bars and digging widths ranging from 500– 1,800mm. For example, when installed on the HS 8130HD crane powered by a 505kW turbo diesel and equipped with twin 350kN free fall winches and main booms of up to 29m length, trenches to depths of 60–90m can be excavated. Critically, in applications such as this, the grab’s hydraulics are protected from contamination by a highpressure filtration system.

Italy’s Soilmec is known worldwide as a leading manufacturer of rotary drill rigs, having manufactured over 5,000 of its SR series machines alone. However, as crane product manager Andreas di Eugenio said, Soilmec has been putting increased emphasis on its crawler cranes: “Since we began our cooperation with Caterpillar about ten years ago we have completely revised our crawler crane line, incorporating top-quality components and electro-hydraulic controls as well as our DMS (Drilling Mate System).

“Today, the Soilmec crane line consists of HD models of 50t, 70t, 90t and 120t capacity and since starting crane production in the mid-1990s, Soilmec has sold some 550 machines.” Obviously, like Bauer, Soilmec’s equipment sales benefit from the demand generated by its parent company, the large foundation contractor Trevi that takes a healthy share of the Soilmec’s production. Nevertheless, its clear that significant numbers of Soilmec cranes complete with slurry grabs, drill rigs and hydromills are being sold to thirdparty buyers.

Earlier this year a 120t (132USt) capacity Soilmec SC 120HD was supplied to Inland Foundation Specialists by Soilmec distributor Western Equipment Solutions of Boise, Idaho. Operating with a Leffer casing oscillator, its first job was to excavate foundations for a new bridge across the St Joseph River at the south end of Lake Coeur d’Aleve. Being itself the foundation division of Inland Crane Company, with a fleet that includes American Hoist, Link-Belt and Demag lattice cranes as well as Liebherr all terrains, the buyer certainly could draw on extensive crane know-how in making its acquisition.

The Japanese manufacturers

Japan’s crawler crane manufacturers are well-established as major forces in the world market for heavy duty hydraulic crawler cranes and have been responsible for numerous technical breakthroughs. This isn’t surprising given that since the early 1960s Japan has established itself as the world’s largest manufacturer. Although production levels are lower today, during the 1960s and 1970s annual domestic demand alone regularly reached 2,000 crawler cranes.

Several Japanese crane manufacturers including Kobelco, HSC (formerly Hitachi-Sumitomo) and Nissha (Nippon Sharyo) continue to manufacture purpose-designed drill and piling rigs as well as crawler cranes. But the landscape is forever changing. Following Kato Works Ltd.’s acquisition of IHI Construction Machinery Co in October 2016 and the subsequent establishment of Kato HICOM, effective March 1st 2018, Kato Works Ltd has fully absorbed the former IHI business. While continuing to offer its CCH line of hydraulic crawler lift cranes of up to 300t capacity (and supplying Terex-American via its successful OEM agreement), it has been some years now since this manufacturer withdrew the last of its heavy-duty DCH series of duty cycle cranes.

Less well-known outside of Japan and Asia is the Nippon Sharyo Company (known as Nissha) which has been a major force in the foundation machinery market since developing the first three-point piling system in 1963 and entering the heavy-duty crawler crane market in 1970. By 1976 Nissha had transitioned from its early mechanical crawler cranes to fully-hydraulic crawler cranes and subsequently developed a full line of machines of up to 150t capacity. In the mid-1990s Nissha licensed the Chinese company Harbin Sihai to manufacture its heavy-duty crawler cranes and piling rigs. For a period in the 2000s Nissha had a working relationship with Ishikawajima Construction Machinery Co. (IHI) that led to the joint development of a heavy duty telescopic boom crawler crane of 90t capacity. However, today, Nissha—a diversified company that amongst other things builds Shinkansen high-speed trains—is focused on purpose-designed hydraulic crawler-mounted piling rigs and reduced its lattice crawler crane line down to a single HD model—the 90t capacity DH 900-5 heavy duty model of 209kW (284hp) introduced in 2009.

The overall reduction in demand for heavy duty crawler cranes is similarly reflected in the HSC and Kobelco line-ups. As an alternative to true heavy duty crawler cranes, both of these leading manufacturers have enhanced the power and hoist performance of their standard lift cranes to provide improved grab crane and pile driving performance. For their domestic and developing markets, Kobelco offers three BM Series heavy duty models of 80t, 100t, and 120t capacity. The largest of these, the BM1200HD introduced at Bauma 2013, is an impressive unit of 116t operating weight and 634kW installed power delivering 314kN maximum hoist line pull. Although these models are not available in Europe, Kobelco does field one European version of its 80-tonner, the BME 800G powered by a 271kW Euro Stage IV Hino turbo-charged and intercooled diesel. However, demand is limited.

Like Kobelco, HSC (formerly Hitachi Sumitomo Cranes) manufactures a series of heavy duty cycle crawler cranes, but no longer markets these in Europe or North America. The range includes models of 80t, 90t and 120t capacity topped by the SCX 1200HD-2 with 272kW installed and a working weight of 131t. However, as Dave Rees, sales director of HSC’s UK distributor NRC Cranes said: “The latest A-3 series of Cummins-powered Lift Crane models in the 100 to 150t range come as standard with 26mm wire rope giving 117kN (11.5t) pull, but there’s the option of specifying a winch with 28mm rope that increases maximum line pull to 132kN (13.5t) which satisfies most of our customer needs”.

As mentioned in our earlier article (Cranes Today November 2018), duty cycle crawler cranes are regulated by EN 474 parts 1 and 12. These regulations define the minimum number of duty cycles that these machines must be approved to perform during their working lives. These are the standards to which suppliers such as Liebherr Werk Nenzing, Sennebogen and others design and build their duty cycle cranes. It’s a very important distinction between these machines and standard lift cranes such as Liebherr’s LR series and Sennegogen’s Starlifter series which are not designed to not meet such standards.

Dynamic compaction

Amongst the first major projects to employ dynamic compaction was the 1980 construction of the General Motors plant near Cadiz where five American Hoist 150USt capacity mechanical lattice crawler cranes were used to consolidate a 150,000m2 area of ‘swampy’ clay using 14USt and 18USt tamper weights of 4m2 surface area. At the same time, one of the pioneers of dynamic compaction, France’s Techniques Louis Menard, used the technique in the construction of an extension to Nice Airport.

During the past ten years, the Chinese manufacturers Sany, Zoomlion, XCMG and Yutong have sold many hundreds of dynamic compaction-equipped crawler cranes, mostly in the 35–60t classes, both at home and throughout Asia and India. All of Europe’s manufacturers offer dynamic compaction set-ups. Middle Eastern markets have provided demand for Liebherr, Bauer as well as Soilmec which has won business in Kuwait and Saudi Arabia. In these applications, their 120t capacity SC- 120HD is equipped with twin 300kN free-fall winches and an anti-slacking system to counteract the hoist rope slackness that inevitably follows the dropping of the pounder weight. At the same time, Soilmec’s DMS system automatically-manages the dynamic compaction cycle according to operator pre-set parameters such as the number of blows, maximum crater depth, drop release height and height of braking intervention. According to project needs and crane capacity, pounder weights vary between 8t and 35t and can be square or circular in shape and manufactured from concrete or steel.

As a means of compaction this is a very sustainable technique, requiring no additional materials, no cement and no water. It increases the bearing capacity of the site, decreases settlement and liquefaction potential for planned building structures. The impact energy of the pounder is transmitted from the surface of the ground to deeper levels by propogating shear and compressive wave types forcing soil particles into a denser state. These stress waves can penetrate as deep as 10m (33ft). Working radius can be varied, albeit in a limited range.

While dynamic compaction is often a very rough affair, Liebherr, like Soilmec, has gone to great lengths to limit the potential for damage to its cranes and their ropes thanks to a system that they patented back in 1989. Using its Litronic control system, Liebherr HD machines thus equipped are able to operate in automatic mode which allows the pounder (or tamper) to be lifted to a pre-determined height and dropped in free-fall mode. The sequence is repeated over and over as long as the control system is in command.

A global market

For the past 18 months a 90t capacity HD crawler crane supplied by another important Italian foundation equipment manufacturer, MAIT SpA, has been operating on the island of Martinique in the Caribbean. Variously equipped with slurry grab for diaphragm wall construction and vibro equipment, the M90HD is the largest crane in the equipment fleet of Soletanche-Bachy subsidiary Bondy Fondaco SAS, based in Fort-de- France, Martinique, and working on residential foundation works.

Demand for HD crawler cranes is every bit as international as for standard crawler lift cranes. While traditional river and canal maintenance work for draglines has declined, these machines remain popular for winning aggregates in markets across Europe, Oceania and the US. For very deep excavations as well as dredging, high-capacity crawler or ship-mounted grab cranes offer a proven, reliable and highly-productive solution. However, foundation work is the major growth sector. Heavilypopulated regions with soft or reclaimed land have always been key markets for foundation work. Of course, in Europe, the Netherlands came to prominence for land reclamation after the tragic floods of 1953 when 2,000 people were killed. That gave birth to the Delta land reclamation plan fuelling massive demand for draglines and foundation machinery that encouraged Ian Pulleman to start his business that eventually became lattice crane and dredger manufacturer PLM Cranes BV. In addition, the Netherlands is also home to several world-famous foundation equipment manufacturers including ICE, PVE and Woltman.

While China has the world’s greatest area of reclaimed land, this is also a major element in island nations like Japan, the Emirates, Singapore, Hong Kong and Taiwan. The development of newly-reclaimed land such as in Dubai (the Palm), Singapore and Hong Kong (airports) has created massive demand for foundation machines. In addition, the high levels of seismic activity in countries such as Japan, Taiwan, New Zealand, Chile, Italy and Iran, drives demand for ever more effective foundation structures. That’s not to mention San Francisco which, unsurprisingly, is home to several leading foundation contractors, such as Malcolm Drilling.