The Strengths of MIYAJI ENGINEERING GROUP, INC.
Strategic and special equipment holdings for handling any kind of construction
05
The most common type of bridge erection construction work is the crane bent erection method. Segmented blocks are received by a bent (a temporary cradle) and successively erected. For locations that are difficult to shut down for long periods of time, such as when erecting bridges over roads or rail lines, special erection methods such as the launching method must be used. This requires a great deal of special erection equipment along with the erection planning capabilities and worksite management capabilities needed to use them. MEG has worked on many difficult special erection construction projects, so it has an extensive track record of developing the special equipment that is necessary. This includes high speed launching equipment for rapidly erecting bridges over railroads and large unit jacks for erecting multiple large blocks at once. When it comes to special erection, we have some of the finest technical capabilities in the industry. Furthermore, expanding large-scale renovation construction work and large-scale construction work, which are highly technically challenging, an extensive pool of special equipment to be on-hand at all times. That's why MEG has four equipment centers in Japan, where it keeps and updates its extensive strategic and special equipment. MEG also has a long track record of using its rich array of strategic equipment to perform emergency recovery work, rapidly restoring social infrastructure damaged by disasters.
That's why MEG has four equipment centers in Japan, where it keeps and updates its extensive strategic and special equipment. MEG also has a long track record of using its rich array of strategic equipment to perform emergency recovery work, rapidly restoring social infrastructure damaged by disasters.
1 What are special erection methods?
(i) Crane bent erection (introduced as a standard construction method)
The crane bent erection method is one of the most generally-employed methods for erecting a steel bridge. Bridge components manufactured at plants are transported to the site, positioned at their correct locations supported by temporary cradle cranes, and joined together, followed by the removal of the temporary supporting columns.
(ii) Launching erection
This is a method in which a lightweight hand spreader (rear girder at the rear if necessary) is attached to the end of a bridge girder that has been assembled on the ground in the adjacent yard in the direction of the bridge axis between the diameters to be bridged and is fed to its regular position using slide jacks, endless rollers, or other hydraulic equipment. Often the girder is fed over an adjacent girder, in which case it must be jacked down to its regular height.
(iii) Travelling crane erection
This erection method was developed for erecting bridge girders with using a traveller crane installed on the bridge being erected. Weights must be reduced in order to perform erection using a traveller crane installed on top of bridge girders. Normal cranes use counterweights to balance the loads they are lifting. However, with this erection method, special facilities are installed to enable the traveller crane to directly leverage the reaction forces of the bridge girders themselves.
(iv) Batch erection using a self-propelled modular transporter
Bridge girders assembled in a separate assembly yard from the erection point are loaded onto a self-propelled modular transporter, which can drive on regular roads, and transported to the erection point and erected. Selfpropelled modular transporters can turn 360 degrees and drive on certain elevation differences and slopes.
(v) Cable crane erection method
When erecting bridges in areas where cranes have difficulty reaching, such as mountainous areas and river areas, two temporary steel towers are erected, and cables are stretched between them. A crane moves on these cables to assemble bridge girders. When bents cannot be used to support the girders that are being assembled, either the cable crane erection method with vertical suspension cable, which uses wire ropes vertically suspended from cables that are provided separately from the cable crane, or the cable crane erection method with diagonal suspension cable, which uses cables diagonally suspended from the temporary steel towers, is used to support the bridge girders.
(vi) Slide-in bridge construction using sliding jacks
Temporary equipment, such as a sliding jack that is installed on bridge piers, is used to horizontally slide girders that were assembled in a place located at the side of their installation point, and install them in their designated position. The advantages offered by this erection method include that it reduces the impact on traffic caused by the crane's angle of depression during crane erection, and that it saves time in works on roads and railroads.
(vii) Batch large block erection using a floating crane
When the bridge erection point is off-shore where large floating cranes (FCs) can be brought nearby, large blocks that are assembled in a quay yard, such as bridge girders and main towers, are erected all at once by using large FCs in a method called the large block erection method. This erection method minimizes the impact on navigation of ships caused by closing off of water around the construction site. In addition, the assembly carried out at stable land on the shore contributes to the improvement of the bridge's quality.
(viii) Batch erection using a large crane
When a yard can be set up near an erection point where large cranes can be assembled, the large block erection method can be used to erect large bridge girders, which were assembled on the ground, all at once over the course of a night by using large cranes. This erection method can minimize the impact on traffic caused by street closures while the erection work is in progress.
(ix) Other special erection methods
In addition to erection methods (i) to (viii) above, MEG has a track record of using its accumulated erection technologies and a wealth of special equipment in various erection methods that are suitable to the site conditions. These erection technologies are used not only for bridges, but also for other types of architecture.
(x) Removal methods
When removing existing bridges, it is vital to take into consideration the people and traffic that use the bridges. This work requires an equivalent or even higher level of technical capabilities than new bridge erection. MEG uses the erection technologies it has accumulated and a number of special equipment for a wide variety of special removal methods.
(xi) Special building construction methods
In addition to its special bridge erection method technologies, MEG also has special construction technologies that are needed to build structures with large interior spaces and special structures. The following are some examples.
2 Our four equipment centers in Japan
[The positioning of equipment within bridge erection]
In steel bridge erection, bridge girder blocks (weighing over 10 tons) manufactured in plants are assembled on-site to create bridges weighing several hundreds to several thousands of tons. In the course of this construction, blocks are transported to the bridge erection site, assembled, and temporarily supported and moved when necessary, until the bridge is completed. One of the notable features of this construction work is that it involves the on-site handling of materials that weigh far more than the materials used in other common civil engineering work.
General-purpose leased machinery cannot handle this large object transport, assembly, temporary support, or more movement. Instead, specialized equipment that is designed for handling large objects is vital for construction work.
Launching method on the river
Slide-in bridge construction (method)
Swing erection of large block around tower
Hoisting erection method of stiffening girder directly below the position
[The advantages provided by our in-house equipment ownership]
In the typical crane bent erection method, erection work can be performed using just general-purpose cranes and temporary bracing members called bents. However, there are many locations where site conditions prevent the use of the crane bent erection method. This includes erecting bridges over railroads or major intersections, in valleys, or over the sea.
In special environments such as these, in which the ordinary crane bent erection method cannot be used, special erection methods must be chosen based on the specific site conditions. Furthermore, construction requires the use of the special erection equipment used in the selected erection method. Special erection construction is impossible without both the special erection equipment and the ability to use it effectively.
The importance of having in-house special equipment is not limited to bridge construction. It has also been an important part of the plan and work of our tower steel framework construction in projects such as Tokyo Skytree and our construction of steel framework for special buildings such as the Tokyo Aquatics Center and Es Con Field Hokkaido.
MEG maintains and manages a large amount of special equipment in its four equipment centers in Japan. We create construction plans based on a thorough understanding of the capabilities and characteristics of our in-house equipment, and we use these plans to carry out safe, efficient construction work.
Crawler crane erection method with temporary support
Cantilever erection method using traveller cranes
Launching erection method with launching girder
Cable crane erection method with diagonal suspension cable for pipe truss arch deck bridges
Construction of Tokyo Aquatics Center
Construction of Tokyo Skytree
[MEG’s equipment centers]
MEG currently operates four equipment centers.
Kurihashi Equipment Center and Hyogo Equipment Center: operated by MEC
Hiroshima Equipment Center and Nasu Equipment Center: operated by MMB
Below is an overview of each equipment center.
| Operating company | Name | Address |
Area (m2) |
Amount of equipment owned (tons) |
|---|---|---|---|---|
| MEC | Kurihashi Equipment Center | Kuki-shi, Saitama | 46,200 | 16,000 |
| Hyogo Equipment Center | Miki-shi, Hyogo | 12,500 | 6,000 | |
| MMB | Hiroshima Equipment Center | Mihara-shi, Hiroshima | 13,500 | 4,000 |
| Nasu Equipment Center | Nasu-machi, Tochigi | 11,300 | 3,500 |
Each of these centers is located at a key transportation site, extremely close to its nearest expressway interchange (generally within 10 km). This makes it possible for equipment to be transported rapidly anytime to construction sites anywhere in the country.
Furthermore, in the event of a large-scale earthquake such as a Tonankai Earthquake, which has recently come to be seen as an inevitability, having multiple equipment centers will make it possible to rapidly respond to disaster equipment dispatch requests in accordance with agreements we have signed with road operators across the country, while at the same time reducing the risk of concentrated damage at a single site.
MEG’s main equipment
1) Travelling crane equipment
Travelling cranes are primarily used in sites such as over rivers, where self-propelled cranes cannot pass under girders.
They are lightweight cranes that are used for cantilever erection over rivers. MEG has over 10 travelling cranes, from small units to large 650 tm cranes.
2) Cable crane equipment
Cable crane equipment is often used in steep mountainous areas and when it is difficult to bring in self-propelled cranes because there is flowing water under girders. Two steel towers are erected, and then taut wire ropes are stretched between them. Loads are then hung from a carrier that runs along the wire ropes, like a ropeway. Cable cranes can be used to transport and erect bridge girders in distant locations where self-propelled cranes cannot reach.
MEG has a variety of cable crane equipment, large and small.
3) Bent facilities
Bents are large temporary supports used when erecting bridge girders. They are the principal type of equipment used in most construction.
MEG, which excels at special erection methods, therefore has an extremely large number of bents. Different bents are used in different projects, depending on site conditions and the sizes of loads. These include bents with pipe-shaped cross-sections, square bents, high load bearing bents, and more.
4) Construction girders (structure erection girders)
These are beams used to support safely heavy bridge girders by combining bents, etc. H-shaped steel girders between 300 and 912 mm high are also used as rails, etc., in slide-in bridge construction. MEG also has many long span construction girders (1.2 to 3 m high) for supporting heavier bridge girders.
Different lengths and heights of construction girders can be used to meet individual worksite needs, so we can allocate equipment optimally on a per-site basis.
5) Launching girders
Launching girders are attached to the ends of girders to safely perform launching of bridge girders over rail areas, rivers, and the like.
They are lighter than bridge girders themselves, and their lengths are adjusted to prevent toppling during launching.
MEG has over 20 I-type girder launching girders. Combined with construction girders, they can be used for launching 100 m or more.
6) Bogies
MEG has numerous bogies for transporting heavy articles such as bridge girders and construction girders.
Self-propelled bogies use the power of motors or hydraulic jacks to propel themselves along rails or construction girders.
7) Special construction equipment
重い橋桁をベント等と組み合わせて安全に支える為に使用する梁材です。高さ300㎜～912mmのH型鋼の梁材は、横取り架設時の軌条設備等としても使用しています。
また、より重い橋桁を長スパンで支える為の工事桁（高さ1.2m～3m）も数多く保有しています。
現場のニーズに応えるべく、高さや長さの異なる様々な工事桁を組み合わせる事により、各々の現場に最適な設備を配置する事が出来ます。
3 Emergency restoration of social infrastructure damaged in disasters
Emergency restoration of social infrastructure damaged in disasters
MEG is making a major contribution to society by using its accumulated technical capabilities and its abundant special equipment to provide a rapid response for emergency restoration of social infrastructure damaged during disasters.
The following are some examples.
①Disaster recovery work following the Great Hanshin-Awaji Earthquake
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Restoration of JR Rokkomichi Station
In the restoration work of the JR Sanyo Main Line Rokkomichi Station, which was severely damaged by the Great Hanshin-Awaji Earthquake in January 1995, we played a major role in the work of jacking up each concrete slab in one piece. This shortened the construction period, which had been expected to take more than two years, to less than three months.
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Expressway No. 3 Kobe Route restoration work
In the restoration of the Hanshin Expressway No. 3 Kobe Route Zone 7, we mobilized all of our available capital in detailed design, fabrication, and erection work. This section of the restoration involved replacing an RC structure viaduct that had completely collapsed in the earthquake with two nine-span continuous steel deck box girder bridges (approx. 5,400 tons). This greatly contributed to shortening the time required to reopen the entire No. 3 Kobe Route, which had been expected to take several years, to only one year and eight months from the earthquake disaster.
Provided by Hanshin Expressway Co.
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Other earthquake restoration work
The Great Hanshin-Awaji Earthquake was the first major post-war earthquake under the city that triggered a major overhaul of the bridge’s earthquake resistance standards, causing extensive damage to bridges on an unprecedented scale. MEG made many contributions to that restoration work. Among them, in the restoration work of Kobe Port Harbor Highway and Port Liner, where significant damage occurred in several long-span bridges including Kobe Bridge and Rokko Bridge, we moved fast from the outset to properly grasp the situation on the ground. This ensured that the right approach was taken early on, which greatly helped toward ensuring a fast recovery. In addition, in the restoration work of the Hanshin Expressway No. 5 Wangan Route, we not only contributed to the early restoration of many bridges, but also contributed greatly to clarifying the disaster mechanism of the Higashi-Kobe Bridge (a cable-stayed bridge) and the Nishinomiya-Ko Bridge (a Nielsen-Lohse arch bridge) based on field surveys.
②Restoration of Joetsu Shinkansen viaduct piers damaged in the Niigata Chuetsu Earthquake
Emergency installation of temporary receiving brackets to prevent further collapse of the viaduct was carried out at the RC viaduct strut of the Joetsu Shinkansen, which had buckled during the Niigata Chuetsu Earthquake in October 2004.
③Restoration of viaduct piers and other parts of the Tohoku Shinkansen damaged by the Great East Japan Earthquake
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Restoration of Kakyoin Overpass
We were able to complete the restoration of the Kakyoin Overpass on the Tohoku Shinkansen in just one and a half months, which had been damaged by the Great East Japan Earthquake in March 2011. The work was completed in time for the resumption of operations at the end of April.
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Tohoku Shinkansen RC viaduct pillar emergency response construction
We also implemented emergency installation of a temporary receiving bracket to prevent further collapse of the RC viaduct strut of the Tohoku Shinkansen, which had buckled near Morioka Station due to the impact of the earthquake.
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Restoration work of Natori connecting passageway on the JR Senseki Line
We also worked on the restoration of the Natori connecting passageway on the JR Senseki Line, which was severely shifted sideways by the earthquake.
④Restoration of the Sixth Abugawa Bridge damaged by heavy rain in Yamaguchi and Shimane
In the restoration work of the Sixth Abugawa Bridge on the JR Yamaguchi Line, which was swept away by torrential rains in Yamaguchi and Shimane in July 2013, the entire company worked together to achieve early restoration of the bridge. This work would normally have required a construction period of two years or more, but we completed it in less than a year from the start of design to the completion of erection.
⑤Emergency work to prevent collapse of the Kumamoto Castle Iidamaru Gokai-Yagura damaged by the Kumamoto Earthquake
Following the Kumamoto Earthquake in April 2016, the Iidamaru Gokai-Yagura (turret) at Kumamoto Castle was in danger of collapsing. The large-scale equipment installed in emergency work to prevent any further collapse was planned and constructed with the utmost care using MEG’s own machinery. We also carried out replacement work for the Tawarayama Bridge (prefectural road Kumamoto Takamori Line) and the First Shirakawa Bridge (Minamiaso Railway), which were severely damaged by the earthquake.
⑥Restoration work of Kagetsugawa Bridge damaged by a heavy rain in northern Kyushu
In July 2017, the Kagetsukawa Bridge on the JR Kyudai Main Line was swept away due to a heavy rain in northern Kyushu. Our design, production, and construction teams worked closely together to respond to strong local demand for early recovery in the restoration. Their efforts helped achieve an ambitious plan by JR Kyushu to restore the entire line in just one year after the disaster.
⑦Restoration work of Hino Bridge (Tokyo) damaged by the Typhoon Hagibis in 2019
MEG carried out restoration work on the Hino Bridge, which became impassable after its piers sank due to Typhoon Hagibis (Typhoon No. 19) in October 2019. In the project that would normally take more than two years, we completed the design, production, and replacement work in only half a year, enabling passage on the bridge to resume.
Click here to see a video of the Hino Bridge disaster restoration work (Tokyo, Japan)
In addition to the above, MEG rushes to the site immediately after a major disaster occurs. Working in cooperation with the Japan Bridge Association, we voluntarily conduct on-site surveys of bridges constructed by MEG. We also hold discussions with road administrators for various initiatives such as emergency recovery works.