Hungary has started on an ambitious highway building programme to improve its infrastructure, but the programme faces considerable cost and time problems because of inherent geological problems with weak soils and high water tables. With Tensar SS biaxial geogrids the contractors have been able to gain full access to the sites, and progress with construction despite unfavourable weather and saturated soil conditions at the beginning of the construction season.
The majority of the land area of Hungary comprises flat, fertile plain, composed mostly of loess loams over glacial clay; the country also has a weather-dictated construction season from spring through to autumn. With 220km of new highway – M6, M7 and M35 – due to be built in 2005, heavier-than-usual spring rains threatened costly delays to progress.
In the autumn of 2004, several trial sections of highway had shown that Tensar SS geogrids with granular fill solved many problems faced by the contractors. The geogrids gave constructors full access to the site for heavy plant, provided a stable working platform for the drain installation rigs, enabled vertical drains to be installed and ensured a fully-reinforced base for the embankment on which the highway is constructed.
The layers of Tensar geogrid and fill created an efficiently-drained stiff platform, which allowed work to continue as if on dry load-bearing ground. Some two million square metres are scheduled to be laid for the road programme in 2005. Light geotextiles were also installed over the sub-base in some areas to prevent fines migration into the granular fill.
Use of Tensar SS geogrid solutions offers time and cost savings compared to conventional methods of providing stable soil conditions for construction and infrastructure projects. In addition, the solutions can often be achieved with poor quality or local fill materials, minimising the amount of high-quality, granular fills that may have to be extracted and transported considerable distances.