Aaron Percy | Department of State Growth

Aaron_Percy_membership
Aaron Percy
Departement of State Growth
Asset Engineer Bridges

Role

I am a member of the Bridge Asset Management Section within the Department of State Growth. Our small team is responsible for the asset management of the bridges, major culverts and other major road related structures on the State Road Network in Tasmania.

My role includes providing specialist technical and engineering advice on the maintenance and rehabilitation of existing structures as well as ensuring new structures will meet our future requirements.

Favourite Corrosion Project

The Tasman Bridge spans between Hobart’s eastern and western shores and is the largest and most important asset that we manage. Over the last 7 years, in particular, a major inspection and several investigations have been undertaken. This has led to a substantial investment in concrete repairs and painting of steel components as well as the implementation of several preventative maintenance strategies. These include replacement of the existing cathodic protection system on the Western Interchange and application of various protective coatings on the concrete columns
and crossheads.

Most notably, the in-water inspection undertaken by divers identified that some of the non-structural (sacrificial) steel pile casings had undergone significant corrosion in recent years. Further investigation and expert advice revealed that the likely cause was Accelerated Low Water Corrosion (ALWC) which is a form of microbially induced corrosion and occurs below low water level. Protective jackets have been installed on the large diameter steel piles in the tidal zone. The protective jackets have in fact been installed to reduce the corrosion rate of the steel pile casings which provide a barrier to the ingress of chlorides into the concrete beneath the casings.

Issues Facing the Industry

Our team manages many old structures in coastal environments which were designed to standards that were not as prescriptive as the current AS5100 – Bridge Design. Chloride induced corrosion has led to expensive treatments including cathodic protection or ongoing concrete repairs to ensure the structures achieve their expected service life.

Current funding priorities require us to keep our older structures in service for longer and ensure that new structures are durable with a low maintenance cost. As such, specifying the right material or coating for a given environment is important as well as good construction practices to ensure that a high-quality durable product is delivered.

ACA Membership

I have attended many seminars and short courses run by the ACA where I have learnt a great deal of technical knowledge and met some wonderful people as well.