Skanska was commissioned by Jämtkraft Elnät AB to construct a weatherproof power grid and lay Optoslang conduits to enable a broadband expansion. On January 1, 2011, a new law took effect prohibiting power outages lasting more than 24 hours. Serious consequences as a result of prolonged power outages are to be avoided.
Power outages due to weather are mainly caused by heavy wet snow or severe storms. Tree branches or entire trees falling onto electric cables can cause a short circuit. The power grid was weatherproofed by burying cables underground and replacing overhead lines with durable insulated lines that can withstand falling trees.
The number of power outages has been significantly reduced and Jämtkraft’s maintenance costs have decreased.
Preparations were made to expand the broadband network to more rural areas in conjunction with the development of the weatherproof power grid. We buried a conduit in the ground that could later be filled with fiber optic cables. A reliable broadband connection renders geographic distance less important.
Jämtkraft Elnät AB was the client for the project and Skanska served as the contractor. The project was carried out as a joint venture between Skanska and Jämtkraft. Most decisions were made jointly, including decisions regarding the procurement of subcontractors. Examples of tasks to be performed by subcontractors included the actual laying of cables and line replacement, controlled drilling, felling and bridge assembly.
All parties participated in the project on equal terms, which meant that everyone was working toward the same goals and that decisions could be made more rapidly. The client, contractor and subcontractors shared any profit or loss.
Skanska’s assignment started in 2006 and was completed in 2011.
Skanska, Jämtkraft and certain external consultants shared an onsite office. Matsola Vestin, Production Manager at Skanska, explained the advantages, “Being under one roof enables us to make important decisions instantly. The client and contractor have the opportunity to discuss various issues and arrive at the best solution simply and quickly. We can look at a drawing together and instantly discuss an alternative solution. Normally, people work in different offices – sometimes in different parts of Sweden.”
The unique skills and expertise of each party were utilized in the project. Skanska has extensive experience of conducting projects and financial reporting. Jämtkraft is an expert in the construction of power grids and possesses local knowledge of its electric cables, connections and customers. Jämtkraft was also responsible for preparatory work, surveying and the supply of materials, as well as obtaining the necessary permits from various municipalities and county administrative boards.
Logistics – one giant puzzle
The logistics involved in a project of this magnitude are like a giant puzzle. The cable trenches were excavated in the summer, the power lines replaced and old lines dismantled in the winter and so on. Skanska’s job was to ensure that the right people were working at the right place at the right time. We were also responsible for making sure that the right machinery and materials were in place so the subcontractors could perform their work and for ensuring that all quality, environmental and work environment goals were fulfilled.
The area in which we were working is as large as the regions of Sörmland and Uppland combined. The large geographic distances involved entailed extremely rigorous logistical demands. Sound planning was key: we always needed to be a few steps ahead. Flexibility was also crucial, since we were sometimes forced to find alternative solutions.
Examples of good planning included ensuring that clearing and felling, drilling under watercourses, bridge assembly and material transportation were all completed before the cable trench subcontractors arrived to bury the cables. No one should have to wait to perform their work.
The project comprised some 300 subprojects, including the laying of cable, replacement of power lines, dismantling, felling and many other tasks, each of which contributed to the overall result. In addition to the actual task of laying cable, which involved burying approximately 1,500 kilometers of electric cable, we also switched to an insulated overhead line stretching some 750 kilometers, dismantled the old power lines and cleared trees along approximately 600 kilometers of power-line paths, which involved the felling of some 40,000 cubic meters of forest.
One way of ensuring that all parties were working toward the same goal was to use checklists that could be filled in by each work group. These lists provided a tool to ensure that the work groups were doing everything correctly, which in turn provided a sense of security and source of support. This boosted our team spirit and solidarity, while improving the quality of our work.
The experience we gained during earlier stages was utilized throughout the project. For example, ground thawing caused problems with limited accessibility on certain roads, forcing us to have materials delivered ahead of schedule.
Project in figures
- Total investment of SEK 1,000,000,000
- 1,540 kilometers of medium and low-voltage cable buried
- 725 transformer stations
- 750 kilometers of power line replaced
- 900 kilometers of cable and power line
- 2,000 kilometers of Optoslang conduit
- About 300 subprojects included in the project