Ex­press­way fall­ing to pieces

Waikato Times - - Front Page - Jo Lines-MacKen­zie jo.lines-macken­zie@stuff.co.nz

Brand new sec­tions of the Waikato Ex­press­way are fall­ing to bits and it’s cost­ing tax­pay­ers dearly.

Engi­neers are still try­ing to fig­ure out how to fix it per­ma­nently and in the mean­time it’s a po­ten­tial risk to mo­torists, a road safety cam­paigner says.

Rut­ting has oc­curred at points in Te Rapa and Nga¯ ru­awa¯ hia af­ter the roads opened in 2012 and 2013 re­spec­tively.

Three in­terim rut­ting re­pairs on the Te Rapa sec­tion have cost the New Zealand Trans­port Agency $755,000 and no fi­nal fix has been found.

The Nga¯ ru­awa¯ hia sec­tion has been re­paired nine times with that cost cov­ered by the con­trac­tor.

Clive Matthew-Wil­son, the ed­i­tor of the car re­view web­site do­gan­dle­mon.com, said ruts on New Zealand roads are a se­ri­ous safety is­sue.

‘‘Many ac­ci­dents start with a loss of con­trol.

‘‘A rut­ted road sur­face af­fects the abil­ity of the driver to con­trol a ve­hi­cle.’’

An out­spo­ken road safety cam­paigner, Matthew-Wil­son said the Waikato ex­press­way’s built-in safety fea­tures should pro­tect mo­torists from ac­ci­dents.

‘‘Be­cause most of this high­way has me­dian bar­ri­ers and road­side fenc­ing, ruts on the road are less of a safety is­sue than they would be on a small ru­ral road.

‘‘How­ever, if one lane of the Waikato ex­press­way has an ob­vi­ous de­fect in the road sur­face, on­com­ing driv­ers may see the de­fect then veer over to avoid it, po­ten­tially caus­ing a col­li­sion with the ve­hi­cle in the next lane.’’

He said that it’s con­cern­ing when a rel­a­tively new road starts giv­ing prob­lems so early.

Matthew-Wil­son be­lieves that the in­cor­rect road sur­face was ap­plied to the Waikato ex­press­way when it was first built.

NZTA is work­ing closely with the con­trac­tor to de­ter­mine the root cause of the rut­ting in Nga¯ ru­awa¯ hia, se­nior man­ager Chris Hunt said.

‘‘The sub­grade ma­te­ri­als be­low the pave­ment used to form the road have per­formed poorly and have be­come weaker when mois­ture con­tent in­creases.

‘‘This re­sults in re­duced sup­port for the pave­ment lay­ers and traf­fic load­ing makes the pave­ment sus­cep­ti­ble to rut­ting.

‘‘As rut­ting in­creases, the pave­ment and road sur­face start break­ing up, al­low­ing more mois­ture to en­ter the pave­ment caus­ing fur­ther and rapid de­te­ri­o­ra­tion of the pave­ment,’’ Hunt said.

The rea­son for the rut­ting at Te Rapa dif­fered as the pave­ment is sup­ported by a thick layer of rock-fill over­lay­ing the ex­ist­ing soil.

‘‘It is be­ing con­firmed through on­go­ing in­ves­ti­ga­tions that the rock layer con­sol­i­dated un­der heavy traf­fic cre­at­ing a loss of sup­port for the up­per pave­ment lay­ers which in turn caused rut­ting and crack­ing of the road sur­face.

Crack­ing of the road sur­face al­lows mois­ture to then pen­e­trate and ac­cel­er­ate the dam­age to the pave­ment.

The Trans­port Agency is work­ing with ex­perts on a longterm re­pair so­lu­tion,’’ Hunt said.

He said that when is­sues be­come ap­par­ent with the Te Rapa and Nga¯ ru­awa¯ hia sec­tions, the Trans­port Agency set about de­vel­op­ing a new pave­ment de­sign that could be con­structed suc­cess­fully in sim­i­lar con­di­tions.

This new pave­ment de­sign is cur­rently be­ing con­structed on the Longswamp, Huntly and Hamil­ton sec­tions of the Waikato Ex­press­way.

The Trans­port Agency has re­ceived one of­fi­cial com­plaint due to the rut­ting which was made by email.

‘‘We pro­vided the com­plainant with in­for­ma­tion on both the work to main­tain the road sur­face, in­clud­ing rut­ting re­pairs and the process be­ing un­der­taken to iden­tify a per­ma­nent so­lu­tion to the rut­ting is­sue.’’

NZTA said rut­ting has not been at­trib­uted to any ac­ci­dents.

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