Most potholes and cracks in local roads are a result of trenching joints from the process of laying new underground water, electricity, wastewater or telecommunication networks, or to repair existing ones, an Infrastructure Malta spokesperson told The Malta Independent.
“When roads are dug up for these works, the reinstatement and resurfacing works to completely compact and seal the cuts made in the asphalt surface creates weak points, that may cause the asphalt to crack and break,” the spokesperson said.
The composition of Malta’s road surfaces
Road surfaces normally include two or three layers of asphalt, depending on their traffic volumes, the spokesperson said. “The bottom (base and binder) layers include imported dolomitic limestone which ensures that the asphalt can attain the required mechanical and physical characteristics.”
“These specifications cannot be met with coralline limestone aggregates sourced from Maltese quarries, which are not used in asphalt utilised by Infrastructure Malta. The topmost (wearing) layer is produced using basaltic aggregate, which increases the road surface’s resistance to the polishing effect of traffic, for increased and longer-lasting skid resistance, even in wet conditions.”
What can be done?
Infrastructure Malta has been looking into different solutions for potholes, including the specification of higher concrete grades for the refilling of trenches and the introduction of reinforcement geogrids over trenching joints to reduce the risk of reflective cracking of road surfaces following reinstatement or resurfacing works, the spokesperson said.
What changes have already been made?
“When it was established in 2018, Infrastructure Malta embarked on an upgrade of the national specifications and other technical benchmarks regulating the quality of infrastructural works carried out by road contractors and other public and private entities, so that they are brought in line with the latest European standards (Comité Européen de Normalisation) and international best practices,” the spokesperson added.
Development of Standards
Through its collaboration with Malta Competition and Consumer Affairs Authority (MCCAA) and other testing laboratories, Infrastructure Malta coordinates “a rigorous testing programme to make sure that works carried out by its contractors meet the required technical specifications. The agency’s quality assurance team commissions over 2,500 tests every year, more than six a day, ranging from concrete and asphalt strength to skid resistance and traffic sign retroreflectivity (night visibility).”
The agency said it is supporting MCCAA to acquire and adopt new testing methods and equipment, such as non-destructive technologies to rapidly measure asphalt strength, reducing the quantity of core samples that are normally extracted from completed road surfaces. “These improvements continue to increase the efficiency of testing processes, facilitating quicker and more accurate reporting and swifter implementation of remedial works and other related actions.”