wellington northern corridor · a new alignment for them. the form of the bridges also ... legend...

www.nzta.govt.nz/otaki-levin-project

Roads of national significance

Wellington Northern corridorŌtaki to North of Levin section

Whirokino Trestle & Manawatu River BridgeThissectionrelatesspecificallytotheWhirokinoTrestleBridgeandManawatuRiverBridgelocatedalongSH1.

TheWhirokinoTrestleBridgeisan1100mlong,reinforcedconcretebridgeconstructedin1938tocarrytrafficovertheManawatufloodplain.Pedestriansandcyclistsuseaseparatepathwayacrossthefloodplainsatgroundlevelalongsidethestructure.

TheManawatuRiverBridgeisa180mlong,steelplategirderstructureconstructedin1942tocarrytrafficovertheManawatuRiver.Therearecurrentlynodedicatedfacilitiesforcyclistsandpedestrians, therefore they use the existing bridge width.

Why do we need to improve these bridges?Bothbridgeseitherneedtobeupgradedorreplacedatsomepointwithinthenext10yearsas they are old, unsafe and narrow. We currently believe that the costs of either upgrading or replacing the bridges will be similar.

We need to make this an efficient freight route and ensure we provide a safe and secure route overtheMotuaFloodwayforyearstocome.

Key issues include:

• NeitherbridgeisstrongenoughtoprovideforHighProductivityMotorVehicles*,resulting in these vehicles needing to take a longer route to access the Wellington region

• TheManawatuRiverBridgehasalackofsafe,convenientcyclefacilities

• Neitherbridgeprovideswideenoughlanesorroadedges

• TheageandconditionoftheTrestleBridgeincreasestheriskofitbeingaffectedbyanearthquake

• Trafficisdelayedbyregularmaintenance,repairsrequired,andtoallowoverweight/widevehicles to cross

• Thecapacityofthefloodwayiscurrentlyconstrainedbythebridges.

*AHighProductivityMotorVehicleexceedsamassof44,000kgand/orthemaximumlengthdimensionsallowedforstandardvehicles,butmeetshigherindividualaxleandaxlegrouplimitsandisnowiderorhigherthanastandardvehicle.ItoperatesunderaroutespecificpermitissuedbyaRoadControllingAuthority(RCA)onroadsandbridgesthathavebeendeterminedtobeable toaccommodatetheadditionalmassand/orlength.

How do we propose to address these issues? We are considering upgrade and replacement options forbothbridges.Ourinitialinvestigations show that the ManawatuRiverBridgecouldbe upgraded or replaced, but it is more than likely that the Whirokino Trestle will need to be replaced.

Ifbothbridgesarereplaced,we need to consider if we keep them more or less on their existing alignment or choose a new alignment for them. The form of the bridges also needs to be considered further.

Inmoredetailthetwooptionswe have considered are:

• Strengtheningandreplacingbridges on the existing statehighway–thiskeepstheexistingrouteandwouldstrengthentheexistingManawatuRiverBridgeandreplacetheWhirokinoTrestleBridgewithasimilarstructureor

• Replacebothbridgesonanewalignment.

Issuesthatwewillneedtoconsiderwhenmakingadecisionare:

• Propertyimpacts–wewillneedtopurchaseasmallnumberofproperties,particularlyifthebridges are to be replaced

• Roadalignment-wemayneedtoimprovesectionsatthenorthernandsouthernapproachestoanynewbridge(s)

• Short-termplan–ifanewbridgeistobeconstructed,ashort-termstrategyofinstallingedgebarriers on both bridges to improve safety could be considered.

Key questions to consider in your feedbackWhat are your thoughts on replacing the bridges

What potential alignment locations do you think would be suitable if both bridges are replaced?

Is there anything else at this location that we should consider?

To Foxton

To Levin

Newth Rd

Ridge Rd

Hic

kfor

d Rd

Otu

roa R

d

Oturoa Rd

Whirokino Rd

Matakarapa Rd

Moutoa Floodway

Manawatu River Bridge

Whirokino Trestle

N

LEGENDExistingSH1BridgealignmentoptionsLocal RdSectionMarker

ALooking south at Whirokino Trestle, the narrow lanes are evident.

Seen from below, the structure’s age is showing.