Four years and 21 bridge crashes

Central Leader - - REAL ESTATE - SI­MON MAUDE

The bridge hit by a truck-born digger has an over-sen­si­tive warn­ing sys­tem that is caus­ing false alarms, ex­pe­ri­enced truck­ies claim.

Truck­ies say cer­tain con­di­tions can set off Penrose over­bridge’s sen­sors on slightly un­der-height loads, frus­trat­ing driv­ers and lead­ing some to pos­si­bly ig­nor­ing the warn­ing sys­tem.

De­spite the warn­ing sys­tem on Penrose over­bridge, since 2012, the bridge has been hit 21 times by over height loads.

A truck driver is fac­ing dan­ger­ous driv­ing charges af­ter his truck haul­ing a digger smashed into the Penrose bridge on May 9. The digger and truck blocked three south­bound lanes for sev­eral hours caus­ing af­ter­noon mis­ery for tens of thou­sands of Auck­land mo­torists and an es­ti­mated $9 mil­lion in lost pro­duc­tiv­ity.

New Zealand Trans­port Agency ( NZTA) fig­ures show Penrose’s bridge takes the lion’s share of Auck­land mo­tor­way net­work bridge strikes at 39 per cent.

Over­all, the agency’s 254 Auck­land mo­tor­way over­bridges have been struck 53 times over the four years.

Auck­land truck com­pany own­ers Todd McGlade and Ian Sped­ding, who have 75 years truck driv­ing ex­pe­ri­ence be­tween them, said the over­bridge’s ap­proach warn­ing sys­tem placed sev­eral hun­dred me­tres be­fore north and south bound mo­tor­way lanes, was er­ratic.

‘‘Some­time the signs are flash­ing but there’s no truck in sight,’’ McGlade said.

Speed­ing said it only had to be ‘‘a windy day’’ to trig­ger the warn­ing signs.

Plas­tic sheet­ing cov­er­ing tall loads could come loose and bil­low up trip­ping the sen­sor, Speed­ing said.

McGlade said a truck ac­cel­er­at­ing could cause its sus­pen­sion to rise, el­e­vat­ing a load higher than it re­ally was.

Auck­land Mayor Len Brown said af­ter the bridge strike that Penrose over­bridge was a con­tin­u­ing haz­ard and it should be re­placed.

Sped­ding agreed and said the 63-year-old span was ‘‘com­pletely out of date’’ and should be re­placed with a higher bridge.

But NZTA said it has no plans to re­place the over­bridge.

NZTA’s Auck­land High­way Man­ager Brett Glid­don de­fended Penrose over­bridge’s warn­ing sys­tem call­ing it ‘‘ex­tremely ro­bust’’ and say­ing it ‘‘does not pro­duce false read­ings’’.

Ad­di­tional sen­sors in­stalled two years ago ‘‘val­i­date’’ the main sen­sor’s warn­ings and most days ‘‘real’’ height warn­ings were trig­gered, he said.

Of­ten warn­ings were caused by flap­ping tar­pau­lins or other flex­i­ble items, Glid­don said, but such in­stances were con­sid­ered ‘‘gen­uinely over height’’.

‘‘They of­ten re­sult in the ve­hi­cle pass­ing un­der the bridge with­out strik­ing it be­cause the items are flat­tened as they go un­der­neath.’’

As mo­tor­ways have in­con­sis­tent road sur­face heights, the agency’s Penrose height warn­ing was set to trig­ger ap­prox­i­mately over 4.35 me­tres, a tol­er­ance that also al­lowed for sus­pen­sion bounce and soft trailer cov­ers, Glid­don said.

A new Penrose over-height warn­ing sys­tem with ex­tra warn­ings would be be work­ing by July, he said.

De­spite mis­giv­ings about Penrose over­bridge’s warn­ing sys­tem, truck­ers McGlade and Sped­ding agreed with trans­port body Road Trans­port Fo­rum that fi­nal re­spon­si­bil­ity for check­ing load heights rested with the driver.

Na­tion­wide civil con­tract­ing com­pany Hig­gins Group, whose truck towed the digger in­volved in the Penrose crash, has re­peat­edly re­fused com­ment on the in­ci­dent.


NZTA say their over height warn­ing signs ap­proach­ing Penrose over­bridge work well.

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