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Roadheaders are gaining widespread acceptance in North America as a means for mechanical tunnel excavation. Until recently, almost all of the large-scale North American tunnel projects were excavated one of two ways ? the tried and true drilland-blast method or with the use of tunnel boring machines (TBM). the hi-tech super-excavators. TBMs enjoyed fast-growing popularity worldwide as TBM manufacturers offered greater technology to meet the demand of the civil tunnel industry in the late 20th century. Recently, though, more tunnel projects, large and small, can thank the brute force of a roadheader for getting the job done.
Brief history
Similar to the TBM, it is not very far back in history that the origin of the roadheader can be found. In 1949, Dr. Z. Ajtay applied for a patent for the first roadheader machine in Hungary. However, there are patents for equipment that looks similar to roadheaders dating back as far as the 1920s. The U.S. patent for the patent for the "Mining Machine" by W.J. Wilson (Fig. 1) is one such example.
The illustration in Fig. 1 looks similar to a current roadheader machine. The roadheader was probably not born a civil tunnel excavator but, instead, as a mining machine. The evolution of the roadheader can almost be seen in Fig.s 2-4 from later U.S. patents (spanning from 1973 to 1978).
The earlier cousin to the roadheader is called the continuous miner. The continuous miner became popular in Europe around 1950 and was probably first introduced in North American coal mines in the mid to late 1950s. Soon, the continuous miner was adapted for civil construction, creating the modern day roadheader. At first, roadheaders were slow to gain popularity among the civil contractors because the early machines were unreliable, often broke down and were difficult to maintain.
Today's roadheaders
Throughout the recent years, roadheader manufactures have come and gone and some have merged as well. FoIlowing is a list of some of the most common names seen on roadheaders:
* Paurat - German manufacturer of heavy duty roadheaders (acquired by Wirth in 1999).
* Dosco - manufactured in the U.K. (affiliated with Meco-Moore). www.dosco.co.uk.
* EBZ - manufactured in China.
* Mitsui Miike - manufactured in Japan since 1 968 (affiliated with SLB roadheaders....