Challenge

A2 (the Sun Motorway) is a major motorway project in Romania between Bucharest and Constanta on the Black Sea. The 50 km Medgidia–Constanta section is currently under construction by the Max Bögl and Astaldi construction groups.

With considerable cut and fill earth moving operations, significant sections of the roadway require very steep slope protection and erosion control, up to a 55 degree inclination.

Faced with the challenge of developing a modern road infrastructure in Romania on limited budgets, the national road authorities require cost-effective, reliable and sustainable construction solutions.

Cellular confinement systems were chosen by the highway planners in advance and specified in the project specs due to their effective erosion control and efficacy in promoting green roadscapes.

Conventional Solution

Conventional slope erosion control methods such as erosion control blankets and mats or geotextiles are not as effective or reliable as geocell systems, while stone, concrete blocks and gabions are much more expensive solutions.

Neoloy Tough-Cell Solution

Neoloy Tough-Cells were selected by the Max Bögl group for erosion protection due to their lightweight strength, durability, and competitive price. Neoloy Geocells sized 356 x 456 (200 mm height) were used for the project, depending on the slope incline.

The 8m Neoloy sections were fastened and cut to the appropriate slope length which ranged between 17-20 meters. After anchoring in the crest shoulder, the sections were opened downslope and anchored with stakes drilled into the hard subgrade with a power hammer.

Due to the hard limestone subgrade, a geotextile separator was unnecessary. Locally available topsoil was used as infill (200 mm height) with an additional 2-5 mm overfill. The slopes were hydro-seeded with wild grass seed. Due to the extreme steepness, straw mulch was applied to enhance seed retention until the grass germinated and rooted.

Some 250,000 square meters of Neoloy were installed in 2011 with a similar amount planned by the end of 2012, the project completion date.