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Modified Bobcat excavator for shaft work

A new Bobcat E88 8.9-tonne mini-excavator has been specially modified in Sweden with a number of features including remote control, for work on building ventilation shafts for the Förbifart Stockholm (Stockholm Bypass) road tunnel project in Stockholm.

Being carried out by main contractor, AF Gruppen, the Stockholm Bypass project is one of Sweden's largest infrastructure projects, to create a series of underground motorway tunnels between the Kungens Kurva interchange in the south of Stockholm and the Häggvik interchange north of Stockholm. Most of this bypass, more than 17 out of 21 kilometres, is being built underground.

The bypass will become the world's third longest road tunnel in the proximity of a city, after the Westconnex Tunnel in Sydney and the Yamate Tunnel in Tokyo. 140,000 vehicles per day are expected to use the bypass.

Created in the north
The Bobcat E88 in Stockholm was originally adapted to meet the special regulations of underground works in the mining region in Kiruna in the north of Sweden. The Bobcat E88 was adapted and supplied by Luleå-based Nordkust Maskin AB, the company responsible for sales and service of the entire Bobcat range in the area from Umeå to Kiruna in northern Sweden. This is in collaboration with Bobcat Sverige AB, the main Authorised Bobcat Dealer for Sweden, with its head office in Kristianstad.

The close proximity of Nordkust Maskin AB was another reason for the choice of the Bobcat E88 excavator, as the company is ideally placed to provide service and support for work in Kiruna. Nordkust Maskin AB managed this project in close collaboration with Bobcat Sverige AB and Bobcat Company and as a result was able to deliver the heavily modified E88 excavator on time for the customer, Bergteamet AB, a specialist shaft and tunnel contractor, based in Boliden in Sweden. Nordkust Maskin is working on another E88 adapted for the mining industry that will also be used for a drilling application.

Bergteamet AB
Founded in 1999, Bergteamet AB brings with it almost a century of mining tradition in northern Sweden. The company developed quickly from offering support services to the local mining industry, to go on to complete major projects both in Sweden and abroad. Today, Bergteamet AB offers a wide scope of expertise and know-how from numerous projects and in a very wide range of geological conditions.

As part of the modifications needed on the E88, it was decided that the ability to remote control the excavator was needed to increase the safety of both the work and the environment. The excavator also needed to be modified to protect it for working in the very harsh environment of the underground vertical shafts.

Bergteamet has been using the Bobcat E88 to sink ventilation shafts for the Stockholm Bypass project. One of the first was at Lovön at Drottningholm outside Stockholm. The process used to construct the shafts begins with making a circular hole at ground level using blasting and hauling the material away.

The next step is to lift the E88 into place in the hole created at the top of the shaft, where the articulated boom allows the machine to fit in the shaft, from where, it can be remote controlled to manoeuvre it into a better position if needed. This includes the use of on-board cameras again driven from a control room, away from any hazardous areas. The E88 is equipped with a tilt-rotator allowing it to be used with a breaker to remove loose material as well as an attachment for rock scaling work. It also has water connections for dust control.

Other attachments/features on the modified E88 include Åkerströms Radio Control, ABL Buckets, Hammerglass explosion proof windows, Lincoln lubrication and a Forrex automatic fire extinguisher. The E88 features a proven, 4-cylinder Bobcat D24 Stage 5 engine with a maximum power output of 48.5kW (65hp). The rear overhang is only 327mm (without an add-on counterweight), allowing this 8.9-tonne machine to be used in confined space areas.

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