Expressway faces work to fix leaks

The slow lanes on the freshly minted Ka¯piti expressway are leaking, and 14 kilometres of it will need resealing, the NZ Transport Agency has revealed.

Project delivery senior manager Chris Hunt said a fix would require resealing long stretches of the 18km expressway in both directions, and the agency would be footing its share of the bill.

The expressway, through the Ka¯piti Coast, started developing discoloured cracks only months after it opened in February.

In June the agency confirmed work would be needed to address ‘‘pavement issues’’ along about 1.26km around the Ka¯piti Rd interchange in Paraparaumu.

Hunt said the repair method would now ‘‘require around 14km of both the north and southbound slow lanes to be resealed’’.

The members of the expressway Alliance, a consortium of contractors and NZTA, would be sharing the costs of the work.

Hunt said contractors were called in after the expressway showed ‘‘signs of minor fatigue’’ in May.

Water was leaking through a seal between the base – or pavement – and the asphalt.

‘‘This has subsequently loosened small particles in the top of the pavement, which causes the discolouration and texture changes.’’

Hunt said there were 3.2km of affected seal, spread over the expressway’s slow lanes, which experienced the heaviest traffic.

‘‘These areas will be treated by reducing the number of joints in the pavement, and joining sections together to provide a more watertight and smoother surface for motorists.’’

This would amount to about 14km of slow lanes being resealed.

The repairs were expected to be completed by the end of the summer work season, next year.

‘‘Until we’re able to define the exact extent of the issue and the areas for remedial works, the cost is unknown.’’

The expressway, one of the Government’s roads of national significance, was completed months ahead of schedule, but Hunt said the application of the seal was not rushed.

‘‘The issue appears to have been caused by the unexpected penetration of moisture through the membrane seal.’’