Access Road Widening, Thaioil Plant, Pataya, Thailand

The 3m wide access road in the Thaioil Plant, Pataya, Thailand presented serious traffic difficulties because of its limited capacity. Therefore, the managing authorities issued a road widening project to allow suitable passage of large vehicles and improve the traffic quality in general.

The construction required the access road to be widened using only the limited 3m space between the edge of the road and the property line of the plant. However, the barbed wire fences along the borderline were not to be disturbed and the widened section needed to maintain the same elevation as that of the original pavement. The conventional solution is to build a 5m high cast-in-place retaining wall and then backfill in layers to the height of the original pavement. However, the barbed wire fences would be totally destroyed because of the required space for the foundation installation. The limited proximity and longer construction schedule finally made such a scheme both impractical and unacceptable.

The design engineer contracted representatives of ACE Geosynthetics and provided ACEGrid^® geogrid as the reinforcing material to build a mechanically stabilized earth (MSE) retaining wall. It was constructed with geogrid wrap-around facing backward in a 5m high staged slope shape. A maximum inclined angle of 80° was designed for the MSE wall so that the most possible width of the access road could be maintained. Each layer of the fill material was installed with a vertical spacing of 50cm. In addition, local available recycled PE sacks were used as the facing materials to help with resource recovery for the owner.

The constructions of the MSE walls are very simple and straightforward. Although the site was constrained, the final widened access road presents excellent construction quality and an improved traffic capacity more than had been originally expected. A few months after completion, the face of the wall presents a natural appearance with blooming local vegetation, and is totally integrated into the environment at the site, making it completely unrecognizable as a man-made structure. Moreover, the completed MSE wall has been through a number of typhoons and by far still remains in good condition. Already in use in hundreds of similar projects, MSE walls with ACE Geosynthetics products have been proved to ensure high performance, cost-effectiveness, and eco-friendliness.