The Norwegian Way of Working
The "Norwegian Way of Working" focuses on safe solutions, high cost efficiency in even the most complex situations , through experts available on site with short, clear lines of communication to reach decisions and the unique decision-making involvement of the shift crew. Bonus agreements with the shift crews are frequently an important element to ensure shared priorities.
The main benefit of Norwegian tunneling is; time and cost efficient tunneling while maintaining excellent work safety, and high final quality without compromising required operational standard and design lifetime.
The Q-system Handbook
The development of the NGI Q-system for rock mass classification began in the early 1970's, and was first published in 1974. NGI has continuously improved and updated the system, and produced the Q-system handbook in 2012 as a summery of NGI's Best Practice. This current edition includes NGI developments and experience gained since the publication of the first edition.
Temporary and Permanent Rock Bolts
The bolt types are used for a variety of different ground conditions and practical purposes, produced to standards and requirements implemented for Norwegian projects. The requirements apply both for temporary bolts, permanent bolts and combination type bolts. Acceptable methods of anchorage, corrosion protection, installation procedures and of course strength and ductility of steel used for rock bolts are specified and implemented as relevant.
This report provide specific information about quality requirements and usage strategies in the Norwegian domestic market.
Risk Sharing Tunnel Contracts
Tunnelling and underground excavation involves handling of uncertainties and the risks associated with the geology frequently lead to claims for "unexpected geological conditions". It may therefore seem favourable to the Client side to use the model of an ECP contract. However, the idea that all risk can be transferred to the contractor, as demonstrated by a lot of failed contracts of this type, shows that it often is wishful thinking. The normal Norwegian approach of unit rate contracts with contractual mechanisms for adjustment of compensation based on actual quantities for rock support and pre-excavation grouting, offers a better alternative. Significant variation of quantities may even lead to contractually regulated adjustment of construction time
Sprayed concrete in tunnelling
The background of this article is underground construction of caverns and tunnels in hard rock, primarily by the drill and blast method and in this field, state-of-the-art means placement by robotic equipment, use of the wet-mix method and mostly with fibre reinforcement. The article is outlining the main parts of the subject, to provide an overview and to present what is considered the right approach for the prospective user of sprayed concrete in hard rock D&B tunnelling.
Water and frost protection in tunnels..
Traffic tunnels in hard rock may be permanently supported by sprayed concrete and rock bolts (see other articles on this Site), but water drips onto roads or rail tracks are normally not acceptable. The standard solution is frequently to install PVC or HDPE welded membrane (inside of a smoothening layer of sprayed concrete and geo-textile roughness protection), supported by cast-in-place concrete lining. When the concrete is not structurally needed for support, then a free-standing sprayed concrete shield ("umbrella") may be used to prevent drips , which can also be frost protection if that is necessary. The overall consumption of concrete can be reduced by 1/2 to 2/3 compared with the standard solution and the carbon footprint of the tunnel improves substantially along with reduced cost.
Digitalisation in Norwegian Tunnelling
This publication describes the current Norwegian use of Building Information Modelling (BIM) with a practical approach. Disciplines like geology, machine operation, Measurement While Drilling (MWD) data utilisation, rock bolting, technical installations and environmental monitoring are included. The major tunnel clients have been nominated as the main contributors to standardisation and future development of the digital processes. By including a chapter for three of the main clients for tunnelling projects in Norway, the publication also provides a wider perspective with regards to future visions and development within the industry. To demonstrate and illustrate successful implementations of digital processes, relevant case-studies are presented.
Sustainability of the inner lining ..
A distinctive feature of Norwegian road tunnels is their inner lining layout in case water or water and frost protection is required. This slender lining detached from the permanent rock support is held by fixation bolts to the rock mass. Apart from material differences, this solution layout has not changed since their first implementations in the early 70’s. This short document aims to reflect the carbon footprint of a typical Norwegian inner lining compared to the traditional double shell lining.