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Showing posts with label 1992. Show all posts
Showing posts with label 1992. Show all posts

21 August 2023

The three stages of the Wellington Inner City Bypass towards Tunnellink

 

Tunnellinkage June 1992

Tunnellinkage June 1992

Wellington Inner City Bypass Programme

History of Wellington Inner City Bypass

The origins of Wellington's urban go back to 1963 when following a report by US consultants De Leuw Cather, it was decided that what was then called the "Foothills Motorway" would be built from Ngauranga to Mt Victoria Tunnel following the foot of Tinakori and Kelburn hills. De Leuw Cather recommended it over a waterfront motorway which would have run along the wharves with ramps connecting to the quays, but it also recommended an underground rail extension to Courtenay Place.  The waterfront motorway concept was quickly abandoned, and the underground rail extension left to the Railways Department to abandon due to cost.

The motorway would bypass the intersections on the busy Hutt Road from Ngauranga south, and take traffic away from the waterfront to bypass the city towards the southern and eastern suburbs.  The motorway was built almost entirely in full as far as Bowen Street, but budgetary constraints saw it curtailed at Willis Street in 1978, with only one of the proposed two Terrace Tunnels built, and with no connection to Ngauranga Gorge. However, the land necessary for the motorway was designated and progressively acquired in the following decades.

With the Ngauranga Interchange opened in 1984, traffic at the end of the motorway at Ghuznee Street started to become a problem, as it now carried both the SH2 and SH1 traffic into Wellington (previously SH1 was the Hutt Road south of Ngauranga to Aotea Quay and then the Quays as far as Taranaki Street.  However funding was not available to complete the motorway (by then scaled down to a grade-separated arterial extension with a 70km/h design speed) throughout the 1980s.  The reforms of 1989 which saw Transit New Zealand set up as a separate state highway manager and land transport funding agency (replacing the National Roads Board and Urban Transport Council) saw revival in interest in progressing the work, but the 1980 design which included severing Cuba Street and an elevated route over Taranaki Street fell out of favour due to concern over aesthetics, noise and severance, which resulted in a cut-and-cover trenched tunnel being the preferred solution by 1992.  This was known as Tunnellink as it was designed to link the Terrace Tunnel and Mt Victoria Tunnel (without duplicating either, as that was not seen as necessary at the time).

Above is one of the newsletters issued by Transit New Zealand about Tunnellink which clearly depicts the route, and the street hierarchy for central Wellington. It also describes clearly how Wellington City Council at the time integrated the proposal into its transport strategy.  At the time it was not clear that Tunnellink would be entirely a state highway project, as SH1 terminated at Willis Street and did not continue to the airport, but that would be changed in the 1995 State Highway Review whereby Transit New Zealand included connections to airports as being of national importance (as seen by the designation of George Bolt Memorial Drive in Auckland as SH20A after the Mangere motorway extension was completed). 

The newsletter clearly shows how Tunnellink was seen was part of a wider transport strategy that was about removing traffic from inner city streets, containing growth of the central city within the boundaries of Tunnellink and the arterial routes along the waterfront, enhancing the "Golden Mile" and integrating the waterfront with the city. It was also seen as critical in enabling improved access for public transport, cyclists and pedestrians. Parking in the inner city was to be constrained, with public transport priority given and even consideration of converting the Johnsonville rail line to a guided busway (subsequently abandoned in favour of lowering the height of the railway tunnels to enable use by new rolling stock).  Integrated ticketing was also part of the strategy, along with footpath widening and cycleways.  It may be worth recalling in 2023 how much thinking in the 1990s was not out of alignment with current trends.

However, funding for road capital spending was severely constrained in the early-mid 1990s and there was little sign that it would be expanded sufficiently or quickly enough to enable Tunnellink to be funded, so in 1995 it was decided to make the Wellington Inner City Bypass (as it had been renamed) coined as a three stage project to achieve short, medium and long-term improvements.

The second leaflet summarises those stages:
  1. Convert Buckle Street westbound and Vivian Street (east of Taranaki Street) eastbound into a one-way pair, to relieve Buckle Street and remove the dangerous chicane of access from Buckle Street across to Dufferin Street. 
  2. Build a new one-way road adjacent from Taranaki Street, using part of Arthur Street across Cuba, Victoria and Willis Streets to a new motorway on-ramp, and converting all of Vivian Street into a new eastbound one-way street as the end of the motorway, severing the Ghuznee Street offramp
  3. Tunnellink
Stage 1 was meant to provide quick temporary relief whilst Stage 2 was progressed and underway. Stage 2 was forecast in 1995 to be adequate for ten-years, by which time it was seen likely to be able to fund Tunnellink.  

In actuality, Stage 2 took much longer as opposition to the project became a cause celebre for some residents in Te Aro, and the Green Party, and it was not until 2007 that Stage 2 was completed, following legal delays and efforts by the Green Party and opponents to get the Government of the day to stop the project altogether.

As Stage 2 was being progressed, Transit New Zealand quietly ceased further efforts to progress Stage 3, as it was seen as too onerous, so focus changed.  An unrelated project to build a new National War Memorial saw part of the route placed in a cut-and-cover tunnel parallel to Buckle Street (under Tory Street) but with sufficient width to connect to a bridge from Mt Victoria Tunnel.  That bridge itself became controversial with Mt. Victoria residents (the bridge designed to relieve congestion at the Basin Reserve westbound) and was shelved in favour of a wider study of SH1 from Ngauranga to the Airport.  That was subsequently expanded in scope to be a wider central Wellington strategic transport project, which is the genesis for what is now called Let's Get Wellington Moving!

08 August 2023

Wellington Urban Motorway extension - Inner City Bypass - Tunnellink

 

Cut and cover tunnel for Wellington Inner City Bypass

With proposals for a second Mt Victoria Tunnel included under Let's Get Wellington Moving and more recently from the National Party's 2023 transport policy, I thought I'd start a series on the Wellington Urban Motorway, which won't be in any specific order, as I have a lot of material on it.  The first article from July 1992, in the former free newspaper "Contact" about the decision by Wellington City Council and Transit New Zealand to play the motorway extension (technically not a motorway but an arterial extension with a 70km/h design speed) into a cut and cover tunnel.  It was previously proposed to go under Willis and Victoria Streets, be at grade across Cuba Street and elevated over Taranaki Street, under Tory Street and Sussex Street. 1.1km of the road would be underground, enabling use of the land above it (although there appears not to have been much calculation of the benefit of doing this).  The proposal also included a "scrubber" to remove noxious particulates and gases from the tunnel exhaust.

The Cut and cover proposal would be coined "Tunnellink" subsequently (to link Terrace and Mt. Victoria Tunnels), but did not include duplicating either of the tunnels, as it was believed there was adequate capacity with those tunnels for some time (and noting that completing the extension would help improve tunnel traffic flow in one direction at least). 

Note the estimated cost in 1992 was only $135m ($281m in 2023 values) which is a far cry from estimates today for a similar project. Note also the depiction of a park in front of the carillon, which reflects that the Arras Tunnel and War Memorial were built around 15 years later than this proposal, but the Arras Tunnel is around the size of more than half of the cut and cover tunnel depicted above.

Financial headaches along the motorway
Financial headaches along the motorway

This second article from the Dominion on September 1993 focuses on the issues with proceeding with the new proposal, including obtaining planning approvals, and also has a short history about the Wellington Urban Motorway.  This included the redesign to be predominantly trenched and then the cut and cover tunnel.  The report also noted that after the extension gets built, a second Terrace Tunnel would be necessary (as the single lane southbound will remain inadequate, and northbound three lanes merge into two). The price for the second Terrace Tunnel was estimated at $63m ($131m in 2023) which also is significantly cheaper than today's construction costs.

Also reported were variations in BCR calculations. A BCR of 20:1 was estimated in 1992, but that had dropped to 2.33:1.  Bear in mind the funding threshold at the time was a threshold of 5:1. Ultimately it was that funding threshold that saw this proposal deferred in favour of the now built Karo Drive "Stage 2" Inner City Bypass. 

Bypass could cut accidents by a third

This final article  from the Evening Post includes a short piece about Wellington City Council backing the extension, but also a report displaying the entire route and claims it would have significant safety benefits by cutting reported accidents by one-third. Noting the design would have retained Ghuznee St as an offramp and Vivian St as an onramp (one way from Taranaki St only), eastbound onramp from Victoria St and offramp westbound, with an eastbound offramp towards Cambridge Tce and another to Dufferin St (for traffic heading towards Adelaide Rd), an onramp from Sussex St westbound (akin to the Arras Tunnel arrangement) and finally eastbound onramp and westbound offramp from Mt Victoria Tunnel.