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 corridor Ōtaki to North of Levin section Whirokino Trestle & Manawatu River Bridge This section relates specifically to the Whirokino Trestle Bridge and Manawatu River Bridge located along SH1. The Whirokino Trestle Bridge is an 1100m long, reinforced concrete bridge constructed in 1938 to carry traffic over the Manawatu flood plain. Pedestrians and cyclists use a separate pathway across the floodplains at ground level alongside the structure. The Manawatu River Bridge is a 180m long, steel plate girder structure constructed in 1942 to carry traffic over the Manawatu River. There are currently no dedicated facilities for cyclists and pedestrians, therefore they use the existing bridge width. Why do we need to improve these bridges? Both bridges either need to be upgraded or replaced at some point within the next 10 years as 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 over the Motua Floodway for years to come. Key issues include: • Neither bridge is strong enough to provide for High Productivity Motor Vehicles*, resulting in these vehicles needing to take a longer route to access the Wellington region • The Manawatu River Bridge has a lack of safe, convenient cycle facilities • Neither bridge provides wide enough lanes or road edges • The age and condition of the Trestle Bridge increases the risk of it being affected by an earthquake • Traffic is delayed by regular maintenance, repairs required, and to allow overweight/wide vehicles to cross • The capacity of the floodway is currently constrained by the bridges. * A High Productivity Motor Vehicle exceeds a mass of 44,000kg and/or the maximum length dimensions allowed for standard vehicles, but meets higher individual axle and axle group limits and is no wider or higher than a standard vehicle. It operates under a route specific permit issued by a Road Controlling Authority (RCA) on roads and bridges that have been determined to be able to accommodate the additional mass and/or length. How do we propose to address these issues? We are considering upgrade and replacement options for both bridges. Our initial investigations show that the Manawatu River Bridge could be upgraded or replaced, but it is more than likely that the Whirokino Trestle will need to be replaced. If both bridges are replaced, 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. In more detail the two options we have considered are: • Strengthening and replacing bridges on the existing state highway –this keeps the existing route and would strengthen the existing Manawatu River Bridge and replace the Whirokino Trestle Bridge with a similar structure or • Replace both bridges on a new alignment. Issues that we will need to consider when making a decision are: • Property impacts – we will need to purchase a small number of properties, particularly if the bridges are to be replaced • Road alignment - we may need to improve sections at the northern and southern approaches to any new bridge(s) • Short-term plan – if a new bridge is to be constructed, a short-term strategy of installing edge barriers on both bridges to improve safety could be considered. Key questions to consider in your feedback What 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 Hickford Rd Oturoa Rd Oturoa Rd Whirokino R d M a t akarapa Rd Moutoa Floodway Manawatu River Bridge Whirokino Trestle N LEGEND Existing SH1 Bridge alignment options Local Rd Section Marker A Looking south at Whirokino Trestle, the narrow lanes are evident. Seen from below, the structure’s age is showing.

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Page 1: Wellington Northern corridor · a new alignment for them. The form of the bridges also ... LEGEND Existing SH1 Bridge alignment options Local Rd Section Marker A Looking south at

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