Auckland Harbour Bridge

From Wikipedia, the free encyclopedia

Auckland Harbour Bridge
The bridge seen from Watchman Island, west of it.
Carries	Motor vehicles
Crosses	Waitemata Harbour
Locale	Auckland City/North Shore City, New Zealand
Maintained by	New Zealand Transport Agency
Designer	Freeman Fox & Partners[1]
Design	Box truss
Material	Steel
Longest span	243.8 metres (800 ft)
Total length	1,020 metres (3,300 ft)
Load limit	13 tonnes (13 LT; 14 ST) on outside lanes
Vertical clearance	4.8 metres (16 ft)[2]
Clearance below	43.27 metres (142.0 ft) at high tide
AADT	168,754
Beginning date of construction	1954
Completion date	April 1959[3]
Opening date	30 May 1959
Toll	Until 30 March 1984
Coordinates	36°49′52″S 174°44′44″E / 36.830985°S 174.745519°E / -36.830985; 174.745519Coordinates: 36°49′52″S 174°44′44″E / 36.830985°S 174.745519°E / -36.830985; 174.745519

The Auckland Harbour Bridge is an eight-lane box truss motorway bridge over the Waitemata Harbour, joining St Marys Bay in Auckland with Northcote in North Shore City, New Zealand. The bridge is part of State Highway 1 and the Auckland Northern Motorway. It is the second-longest road bridge in New Zealand, and the longest in the North Island.^[4]

The bridge has a length of 1,020 m (3,348 ft), with a main span of 243.8 m, rising 43.27 m above high water^[5] allowing ships access to the deepwater wharf at the Chelsea Sugar Refinery west of it (one of the few wharves needing such access west of the bridge, a proposed Te Atatu port having never been realised).^{[6][citation needed]}

Contents 1 Background 2 Construction 2.1 Initial structure 2.2 'Nippon clip-ons' 3 Traffic management 4 Proposed walk and cycleway 5 Second Harbour Crossing 6 See also 7 References 8 External links

[edit] Background

Prior to construction of the bridge, the quickest way from Auckland to the North Shore was via passenger or vehicular ferry. By road, the shortest route from Auckland to the North Shore was via the Northwestern Motorway (then only completed between Great North Road and Lincoln Road), Massey, Riverhead, and Albany – a distance of approximately 50 kilometres (31 mi).^[7][8]

As early as 1860, engineer Fred Bell, commissioned by North Shore farmers wanting to herd animals to market in Auckland, had proposed a harbour crossing in the general vicinity of the current bridge. It would have used floating pontoons - but the plan failed due to the £16,000 cost estimate, NZ$1.6 million in inflation-adjusted terms (2009).^[8]

At the time of the 1950s, when bridge plans were finally realised, North Shore was still a very rural area of barely 50,000 people, offering relatively few jobs, and its growth rate was half that of the Auckland south of the Waitemata. Opening up the area via a new main road connection was to unlock the potential for further expansion of Auckland.^[8]

[edit] Construction

[edit] Initial structure

Based on recommendations of the design team and the report of the 1946 Royal Commission, the bridge was to have five or six traffic lanes instead of four (with the extra one or two lanes intended to be reversed in direction depending on the flow of traffic), as well as footpaths on both sides of the bridge. However, these features were dropped for cost reasons before construction started, the First National Government of New Zealand opting for the 'austerity' design of four lanes without footpaths, and only including an approach road network after local outcry over traffic effects.^[9] The decision to reduce the concept in this way has been called "a ringing testament to [...] the peril of short-term thinking and penny-pinching".^[9]

The bridge took four years to build, with Dorman Long / Cleveland Bridge Co. being the original contractors.^[1] The large steel girder sections were partially pre-assembled, and then floated into place on construction barges. One of the main spans was almost lost during stormy weather when the barge began to drift, but the tugboat William C Daldy eventually won a 36-hour tug-of-war against the high winds.^[10]

Having been completed in April 1959, three weeks ahead of schedule,^[11] the bridge was officially opened on 30 May 1959 by the Governor-General Lord Cobham,^[12][13]. Previously, an open day had been held during which 106,000 people had been allowed to walk on the bridge.^[3]

According to various sources either three or four men had been killed by accidents during construction, and the names of three of them are recorded on a memorial plaque underneath the bridge at the Northcote end.^[14][15]

Paid for by government-backed loans,^[14] the bridge started out as a toll bridge, the first such facility in New Zealand,.^[9] with toll booths for both north and south-bound traffic located at the northern end. Tolls were originally 2/6 (25 cents) per car but were reduced to 2/- (20 cents) after 15 months of operation. Tolling was later made south-bound only before being discontinued on 30 March 1984, and the booths removed.^[16] This was in line with political commitments that tolls would only be charged until the bridge's construction costs were paid off.

Some critics have also alleged that the rerouting of State Highway 1 over the bridge was motivated by the need to create toll revenue, and led to a decade-long (and ongoing) delay on finishing the Western Ring Route around Auckland. The rerouting is thus alleged to have significantly contributed to the need for a massive motorway through the city centre of Auckland, severely damaging inner city suburbs like Freemans Bay and Grafton.^[17]

[edit] 'Nippon clip-ons'

The bridge was originally built with four lanes for traffic. Owing to the rapid expansion of suburbs on the North Shore and increasing traffic levels it was soon necessary to increase the capacity of the bridge - by 1965, the annual use was about 10 million vehicles, three times the original forecast.^[9]

In 1969, only ten years after opening, two-lane box girder clip-on sections were added to each side, doubling the number of lanes to eight. The sections were manufactured by Ishikawajima-Harima Heavy Industries of Japan, which led to the nickname 'Nippon clip-ons'. The selection of the company was considered a bold move at the time, barely 20 years after WWII and with some considerable anti-Japanese sentiment still existing in the country.^[18] The costs of the additions were noted as having been much higher than had the extra lanes been provided initially.^[9]

While doubling the vehicle lanes of the bridge, the clip-ons have been plagued by significant issues. In 1987 cracks required major repair works,^[19] and in 2006, further cracks and signs of material fatigue were. The clip-ons were originally to have a life expectancy of 50 years.^{[citation needed]} Auckland City Council's Transport Committee requested Transit New Zealand to investigate the future of the clip-on lanes as part of its 10-year plan. Transit noted in this context that the plan already includes some funding for bridge maintenance.^[20]

In May 2007, Transit New Zealand proposed a bylaw change to restrict trucks over 4.5 tonnes from using the outside lane on each clip-on to reduce stress on the aging structure.^[21] This was later changed to a bylaw introduced in July 2007 restricting only vehicles of 13 tonnes or more, based on the high level of voluntary compliance during the previous months.^[22]

In 2007, it was announced that NZ$45 million in maintenance work on the clip-on sections was being pulled ahead as part of good practice. In October 2007 a 2006 report from Beca Group surfaced in the press, noting that the clip-ons were at risk of catastrophic, immediate failure in certain circumstances (such as a traffic jam trapping a large number of trucks on them). Transit New Zealand has noted that the situation described was extremely unlikely, and measures already implemented would prevent it from occurring.^[23] In January 2008, it became known that even after the multi-million dollar maintenance works, a full ban for trucks on all clip-on lanes might be required, or the working life could be reduced to only 10 more years.^[24]

[edit] Traffic management

A "tidal flow" system is in place, where the traffic direction of two of the centre lanes is changed in order to provide an additional lane for peak period traffic. During the morning rush five of the eight lanes are allocated to southbound traffic, heading towards Auckland. This situation is reversed in the afternoon, when five lanes are allocated to northbound traffic. At all other times of the day the lanes are split evenly, and peaks also have grown increasingly evenly distributed (i.e. in 1991 there was often a higher than 3:1 difference in directional traffic, in 2006 this had dropped to around 1.6:1). The bridge has an estimated vehicle capacity of 180,000 per day, and in 2006 had an average volume of 168,754 vehicles per day (up from 122,000 in 1991).^[25]

For many years lane directions were indicated by overhead signals. In the late 1980s a number of fatal head-on accidents occurred when vehicles crossed lane markings into the path of oncoming traffic. In 1990, a movable concrete safety barrier was put in place to separate traffic heading in opposite directions and eliminate head-on accidents. Two specially designed barrier machines moved the barrier by one lane four times a day,^[19] at a speed of 6 km/h. It took 40 minutes to move the entire barrier, which was the first of its kind in the world.^{[citation needed]}

In March 2009 both the barrier transfer machines, which lasted four times their original design life of five years, and the original barrier were replaced. The new barrier transfer machines are capable of moving the barrier in half the time the old machines did. The concrete barrier blocks and the metal expansion blocks have been reduced in width by 20 cm, giving more width in the lanes either side of the barrier.^{[citation needed]}

[edit] Proposed walk and cycleway

Proposal

When the bridge was built the originally envisaged rail lines, walking and cycling paths were dropped for cost reasons,^{[citation needed]} and neither were they included during the clip-on construction (tourists can walk on the span via guided tours). In recent (2007) discussions about the future of the bridge, the addition of a cycle and footpath link between Auckland City and North Shore City has been mooted for the bridge. Transit New Zealand has noted that such a provision would cost between NZ$20 million and $40 million, but public support for such an addition to the bridge has been polled as being very high.^[26] The GetAcross group and Cycle Action Auckland argue that lower-cost options are available, and that provision for a walk- and cycleway could relatively easily be included in the bridge strengthening works currently being planned for the clip-on structure.

The GetAcross group has created a webpage showcasing the proposed walking/cycling solution and invites visitors to sign a petition supporting or opposing the proposal.^[27]

A 2008 proposal to modify the clip-ons and potentially widen them to add walking and cycling paths to the bridge met with different reactions. While Auckland Regional Council and North Shore City Council voted to support it (under certain conditions), Auckland City Council considered the costs associated with the proposal as too high. Other stakeholders such as the New Zealand Transport Agency (NZTA) also consider the proposal as not having enough merit for the $22–53 million price tag, though campaigners note that the costs cited for the project include 45% contingencies.^[28] A proposal from the Auckland Regional Council (one of the proponents of the facility) to open up part of the clip-on structure for a walking / cycling trial use during several summer weekends - to show whether it would attract enough users - did not go forward.^[28]

Protests

On Sunday, 24 May 2009, thousands of people, including many families, crossed the bridge as a part of a protest by the GetAcross group against the fact that after 50 years of existence, the bridge still did not provide walking and cycling access, and against what the group perceives to be the authorities' negative and obstructionist attitude towards retrofitting such infrastructure.^[29] A crossing as part of the protest (or as part of the official 50 year anniversary celebrations) had been forbidden by NZTA for safety reasons (respectively because of the costs and traffic difficulties claimed for a managed crossing). However, after several speeches, including by Auckland Regional Council Chairman Mike Lee, several individuals managed to make their way around the edges of the police cordon to walk and cycle onto the bridge. At that stage police saw no choice but to close off the northbound traffic lanes, bringing State Highway 1 to a stop in the northbound direction. This in turn resulted in the remainder of the protesters moving onto the bridge (which was not resisted anymore by the police at that stage). No accidents, violence or arrests were reported,^[29] and protesters left the bridge approximately an hour later, many having crossed all the way to North Shore and then returned.

The protest created a wide spectrum of responses in the media and in public perception, from being labelled a dangerous stunt representative of an increasingly lawless, anarchic society^[30] to being considered a successful signal to authorities to give more weight to the demands and the public backing of the walk and cycleway proponents. Authorities noted that they are investigating whether any of the protesters would face fines or charges.^[31] NZTA representatives noted that they were disappointed at what they considered the broken word of the organisers of the protest, and remarked that it would take 30 more years before walking and cycling could likely be provided on the bridge (see also "Second Harbour Crossing" below).^[29] NZTA were however also criticised as having brought the situation at least partly onto themselves by choosing the easy route of forbidding the protest crossing.^[30] Several political protest marches (especially hikois) had in the past been allowed to cross the bridge.

[edit] Second Harbour Crossing

Almost since the Harbour Bridge reached capacity (i.e. before extension via the clip-ons) a second crossing of the harbour was mooted. The extreme costs and the difficulties of connecting it to the motorway network have however so far caused plans to remain at concept stage. However, in 2008, a study group narrowed down around 160 options to a single recommendation, a multi-tunnel link approximately one km east of the existing bridge, with up to four individual tunnels for motorway and public transport and trains. The proposal however has not continued to a political decision or funding stage.

[edit] See also

General

• Public transport in Auckland
• Transport in Auckland
• Bridges in New Zealand

Specific

• Central Motorway Junction, the major motorway junction connecting southeast of the bridge
• Newmarket Viaduct, similarly important traffic bottleneck on other side of Auckland CBD
• Western Reclamation, large industrial area east of the bridge, possible southern end of second crossing

[edit] References

[edit] External links

Wikimedia Commons has media related to: Auckland Harbour Bridge

• Auckland Harbour Bridge in the Structurae database
• Historical photos (from the Transit New Zealand website)
• Historical photos (from a private website)
• Get Across (Cycle Action Auckland website promoting a Harbour Bridge cycling facility)

Coordinates: 36°49′52″S 174°44′44″E / 36.830985°S 174.745519°E / -36.830985; 174.745519