2012 – Tonga – Introducing Otta Seals for Low Volume Roads in Tonga

The Kingdom of Tonga’s road network, comprising approximately 640km of public roads, has had minimal road maintenance over the past decade. As a result, the road network is rapidly deteriorating. The World Bank funded Transport Sector Consolidation Project is supporting the Government of Tonga in implementing a road maintenance program to prolong the serviceability of the road network. However, due to the limited capacity of the local contracting industry, and a severe lack of quality road surfacing aggregate, traditional surfacing methods for periodic maintenance and road upgrading are not suitable. Innovative surfacing technologies, such as Otta Seals, were adopted to overcome the local limitations. The main objective of this paper is to document the introduction of Otta Seals to Tonga and the experience to date. It will also briefly capture the applications, benefits and limitations of Otta Seals, and the reasons why they have been considered for Tonga. The paper provides a brief review of the local contracting industry and the availability of locally sourced aggregate in Tonga, and the effects that these have on the choice of pavement surfacing alternatives. The first trial sections were awarded to a local contractor in January 2012, and the works were started after the rainy season in July 2012. The process of introducing the new technology has to date been successful and progress of this project is being monitored by a number of other South Pacific countries that are faced with the similar constraints.