Kaimai Tunnel
Encyclopedia
The Kaimai Tunnel is a railway
tunnel through the Kaimai Range in the North Island of New Zealand
. Since it was opened in 1978, it has held the title of longest tunnel in New Zealand, assuming this distinction from the previous title holder, the Rimutaka Tunnel
. It is part of the Kaimai Deviation, which was constructed to bypass the old route of the East Coast Main Trunk Railway through the Karangahake Gorge
(part of which has been preserved as the Goldfields Railway
).
The Kaimai Deviation is a 24 km line between Waharoa
and Apata, including several major cuttings, embankments and viaducts, while the tunnel makes up 8.85 km of this distance 5 km from the Apata end of the line.
In 1955, an investigation was made of the possibility of road and rail access to Mt. Maunganui from the Waikato including a 4 km tunnel, an idea that was enthusiastically supported by Federated Farmers, and later local news media. This led to the formation of the Kaimai Tunnel Committee.
Hopes for a timely start on such a line were dashed, when on 14 August 1958 it was announced that the project was to be deferred. A report that had been prepared on the subject stated that there was an insufficient volume of guaranteed traffic then or in the near future to justify the project at that time. Alternatives were mentioned, including a preferred 24 km route between Waharoa and Apata with a 9 km tunnel (essentially what ended up being the Kaimai Deviation). The budget for such an option was expected to be at least NZ$
10.5 million. It was felt that there was still sufficient capacity on the existing line, and that the idea should be reviewed when demand required it.
In conclusion, the commission postulated that freight traffic to the Bay of Plenty would double by 1982, a feat that was actually attained in 1966. It also made the following recommendations:
Following the publication of this report in 1963, the government authorised a survey of the whole deviation route. However, it was not until September 1964 that the project was actually approved at an estimated cost of $11,434,000. In November, construction was further delayed by six months until funding of $710,000 was finally approved in the following years budget for the 1965-1966 financial year. It was expected at the time that the project could be completed by October 1970.
(who was also the MP for the Bay of Plenty) officiated. The Chief Civil Engineer remarked at the time that the deviation would be an advantage to the whole North Island railway system, shortening the rail distance between Tauranga and Hamilton by 51½ km, and the rail distance between Rotorua and Tauranga by 100 km. He expected that the construction costs could be recovered through savings on operational costs once the deviation was completed.
The work was carried out primarily by the Ministry of Works, who were responsible for the drilling of the tunnel. Various other related jobs were handled by private contractors, including the tunnel approaches and the laying of the track bed in the tunnel.
In planning for the construction of the tunnel, the possibility of using a Tunnel Boring Machine
(TBM) was considered in 1966. Discussions were held in Australia with those that had experience with them, or had previously investigated using them, and as a result, it was felt that further investigations into the idea were justified. Rock samples were submitted to the manufacturers (Jarva Company) for an assessment of the suitability of the machines for the tunnel project. It was felt that such a machine would be able to handle the eastern end of the tunnel, but that the western end could pose problems if the rock was found to be too fractured.
The Jarva tunnelling machine was purchased and imported from the United States
in 1970 at a cost of $1.4 million, a decision considered adventurous at the time as a TBM had not been used on this type of geology before. Despite concerns about starting at the western portal with the TBM, it was considered to be the better option to alleviate problems with drainage that would ensue otherwise because of the 1:300 ascending grade from west to east. Also, the tunnel was to terminate at the eastern end on a viaduct over the Whatakao Stream which had yet to be built.
Construction of the tunnel started at the western end on 15 January 1969 with the excavation of the approach cutting which reached 25 m deep at the portal. A layer of alluvial material at the tunnel face meant that this section had to be excavated by hand, first as a small pilot tunnel, later being enlarged to the final size.
It was at this time that the only lives were lost on the project. A cave-in, caused by a high ground water level, resulted in the loss of four lives. The rescue operation was able to save eight other workers who were trapped with those that perished.
Tunnelling resumed after a delay of several months, and by 1971 the TBM was ready to commence work. A three-month trial period had been allocated to assess the suitability of the TBM for work at the western portal. It soon became apparent that the nature of the rock at this end of the tunnel was too fractured for efficient operation of the TBM, resulting in the cutters and fill extraction systems of the machine being continually blocked by rock. By the end of the trial period, the TBM had only advanced 106 m and was wearing out far more quickly than was hoped, so it was decided to dismantle it and move it to the eastern portal.
Work at the western end of the tunnel continued with traditional drill and blast methods. The profile of the western end, which had been round to accommodate the TBM, was changed to a horseshoe shape to better suit conventional tunnelling procedure. By the time the tunnel was finished, around 48% of the length of the tunnel had been bored using conventional methods.
Reasonable progress was made from the eastern end of the tunnel once the TBM had been reassembled there in April 1972. Though the wear on the machine caused by its use at the western end caused some mechanical problems, progress of up to 15 m per 8 hour shift was achieved, though this was considerably reduced in wet areas. With up to 600 m³ of water flowing through the tunnel walls, continuous pumping was required to avoid flooding.
Ducted ventilation was initially sufficient for the machine and the workers in the tunnel, but the closer the excavation got to the midway point, the more the temperature increased. To combat this, the shifts were shortened, though eventually three refrigeration plants had to be installed for the western end and one at the eastern end.
The project plan had called for lining to be done once all excavations had been completed, but deteriorating rock, especially at the western end, meant that the plan had to change. The problem was solved by pumping concrete under high pressure behind steel liners. Once this was finished, the concrete track bed was laid by the private contractor Robert McGregor and Sons of the United Kingdom
. Together with British Rail, they had developed a technique for laying paved concrete track (PACT). This method was chosen rather than the traditional ballast and sleepers to reduce maintenance costs for the track inside the tunnel.
After a lunch stop at Matamata, Prime Minister
Robert Muldoon
greeted the assembled crowd and boarded the train. The next stop was Hemopo, where a crowd had assembled. They were addressed by Piako County Council Chairman Mr. Thomas, the MP for Piako Mr. Jack Luxton
and the Minister of Railways
the Hon. Colin McLachlan
. Then the Prime Minister gave a speech, and unveiled a plaque paying tribute to the four workers who had lost their lives. Finally, he cut a ribbon and declared the tunnel to be open. The train proceeded to Tauranga with the official party and minus the school children where several civic functions were held.
The project ended up running eight years over time, and over budget. The final cost was $43 million for the tunnel and $13 million for the deviation, a total of $56 million.
Traffic on the Kaimai Deviation has been dominated by freight trains for its entire working life. Regular passenger trains to the Bay of Plenty had ceased in 1967 with the final running of a post-Taneatua Express
88 seater railcar
service; the lengthy and time-consuming route that the tunnel replaced was part of the reason this railcar service had ceased to be viable. It was not until 9 December 1991 that a regular service to the Bay of Plenty was re-introduced. Named the Kaimai Express after the tunnel, it ran between Auckland and Tauranga until its cancellation on 7 October 2001. For its entire existence, it was operated with Silver Fern railcars. Since the Railways Corporation relaxed its policy on private use of the national rail network in the 1980s, there have been occasional passenger excursions run on the deviation by organisations such as Mainline Steam
and the Railway Enthusiasts Society
.
A peak of the Kaimai directly above the tunnel, previously unnamed, was named Stokes Peak in 2010 in honour of geographer Evelyn Stokes
.
Rail transport in New Zealand
Rail transport in New Zealand consists of a network of gauge railway lines in both the North and South Islands. Rail services are focused primarily on freight, particularly bulk freight, with limited passenger services on some lines...
tunnel through the Kaimai Range in the North Island of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
. Since it was opened in 1978, it has held the title of longest tunnel in New Zealand, assuming this distinction from the previous title holder, the Rimutaka Tunnel
Rimutaka Tunnel
The Rimutaka Tunnel is a railway tunnel through New Zealand's Rimutaka Ranges, between Maymorn, near Upper Hutt, and Featherston, on the Wairarapa Line.The tunnel, which was opened to traffic on 3 November 1955, is long...
. It is part of the Kaimai Deviation, which was constructed to bypass the old route of the East Coast Main Trunk Railway through the Karangahake Gorge
Karangahake Gorge
The Karangahake Gorge lies between the Coromandel and Kaimai ranges, at the southern end of the Coromandel Peninsula in New Zealand's North Island. A sharply winding canyon, it was formed by the Ohinemuri River. State Highway 2 passes through this gorge between the towns of Paeroa, Waikino and Waihi...
(part of which has been preserved as the Goldfields Railway
Goldfields Railway
The Goldfields Railway is a heritage railway that operates between Waihi and Waikino in the Bay of Plenty region of New Zealand's North Island. It operates over a section of track that was part of the East Coast Main Trunk Railway until the Kaimai Tunnel deviation made it redundant in 1978...
).
The Kaimai Deviation is a 24 km line between Waharoa
Waharoa
Waharoa is a rural community in New Zealand.Waharoa is the railway junction of the Kinleith Branch railway with the East Coast Main Trunk Railway.State Highway 27 runs through the town.-Schools:...
and Apata, including several major cuttings, embankments and viaducts, while the tunnel makes up 8.85 km of this distance 5 km from the Apata end of the line.
History
In the first half of the 20th century, the disadvantages of the East Coast Main Trunk route through the Karangahake and Athenree gorges became starkly apparent. The capacity of the line was constrained by several factors; its length, severe grades of up to 1:50, sharp curves of up to 6 chains radius, and light 55 lb per yard rail which prohibited the use of the more powerful diesel locomotives. It was also an unreliable route, with frequent disruptions caused by slips.Proposals
Proposals to shorten the distance between Auckland and Tauranga were made as far back as the early 20th century. A line over the Kaimai Range was suggested in 1911 but was quickly dismissed as being impractical. In 1913, a 3.2 km tunnel was suggested, and in 1920 a survey was requested for a Kaimai rail route, though it would be many years before this happened.In 1955, an investigation was made of the possibility of road and rail access to Mt. Maunganui from the Waikato including a 4 km tunnel, an idea that was enthusiastically supported by Federated Farmers, and later local news media. This led to the formation of the Kaimai Tunnel Committee.
Hopes for a timely start on such a line were dashed, when on 14 August 1958 it was announced that the project was to be deferred. A report that had been prepared on the subject stated that there was an insufficient volume of guaranteed traffic then or in the near future to justify the project at that time. Alternatives were mentioned, including a preferred 24 km route between Waharoa and Apata with a 9 km tunnel (essentially what ended up being the Kaimai Deviation). The budget for such an option was expected to be at least NZ$
New Zealand dollar
The New Zealand dollar is the currency of New Zealand. It also circulates in the Cook Islands , Niue, Tokelau, and the Pitcairn Islands. It is divided into 100 cents....
10.5 million. It was felt that there was still sufficient capacity on the existing line, and that the idea should be reviewed when demand required it.
Commission of Inquiry
Local interests were not satisfied with the 1958 report, and continued to prevail upon the government for action. In 1960, a deputation met with the Minister of Railways in order to impress upon him the importance of a replacement for the existing route, and as a result, a Commission of Inquiry was established in August 1962 to investigate “Improved Access by Land to the Port of Tauranga and Bay of Plenty”. During the commission’s hearings in October, submissions from 38 individuals and groups were heard and 261 pages of evidence submitted.In conclusion, the commission postulated that freight traffic to the Bay of Plenty would double by 1982, a feat that was actually attained in 1966. It also made the following recommendations:
- The construction of a deviation from Waharoa to Apata through the Kaimai Range, and the closure of the Paeroa to Apata section of the East Coast Main Trunk.
- The construction of a Rotorua to Paengoroa deviation to eliminate the Mamaku Bank on the Rotorua BranchRotorua BranchThe Rotorua Branch is a railway line from Putaruru to Rotorua, in the Waikato and Bay of Plenty regions of the North Island of New Zealand. Construction of the line was commenced by the Thames Valley and Rotorua Railway Company and finished by the Public Works Department...
. - An extension of the Rotorua Branch to the Waipa State Mill.
Following the publication of this report in 1963, the government authorised a survey of the whole deviation route. However, it was not until September 1964 that the project was actually approved at an estimated cost of $11,434,000. In November, construction was further delayed by six months until funding of $710,000 was finally approved in the following years budget for the 1965-1966 financial year. It was expected at the time that the project could be completed by October 1970.
Construction
At the turning-of-the-first-sod ceremony on 2 October 1965, the Minister of Works the Hon. Percy AllenPercy Benjamin Allen
Percy Benjamin Allen was a New Zealand politician of the National Party.He represented the Bay of Plenty electorate in Parliament from 1957, when he won the 1957 by-election after the resignation of William Sullivan, until 1975, when he retired....
(who was also the MP for the Bay of Plenty) officiated. The Chief Civil Engineer remarked at the time that the deviation would be an advantage to the whole North Island railway system, shortening the rail distance between Tauranga and Hamilton by 51½ km, and the rail distance between Rotorua and Tauranga by 100 km. He expected that the construction costs could be recovered through savings on operational costs once the deviation was completed.
The work was carried out primarily by the Ministry of Works, who were responsible for the drilling of the tunnel. Various other related jobs were handled by private contractors, including the tunnel approaches and the laying of the track bed in the tunnel.
In planning for the construction of the tunnel, the possibility of using a Tunnel Boring Machine
Tunnel boring machine
A tunnel boring machine also known as a "mole", is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. They can bore through anything from hard rock to sand. Tunnel diameters can range from a metre to almost 16 metres to date...
(TBM) was considered in 1966. Discussions were held in Australia with those that had experience with them, or had previously investigated using them, and as a result, it was felt that further investigations into the idea were justified. Rock samples were submitted to the manufacturers (Jarva Company) for an assessment of the suitability of the machines for the tunnel project. It was felt that such a machine would be able to handle the eastern end of the tunnel, but that the western end could pose problems if the rock was found to be too fractured.
The Jarva tunnelling machine was purchased and imported from the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in 1970 at a cost of $1.4 million, a decision considered adventurous at the time as a TBM had not been used on this type of geology before. Despite concerns about starting at the western portal with the TBM, it was considered to be the better option to alleviate problems with drainage that would ensue otherwise because of the 1:300 ascending grade from west to east. Also, the tunnel was to terminate at the eastern end on a viaduct over the Whatakao Stream which had yet to be built.
Construction of the tunnel started at the western end on 15 January 1969 with the excavation of the approach cutting which reached 25 m deep at the portal. A layer of alluvial material at the tunnel face meant that this section had to be excavated by hand, first as a small pilot tunnel, later being enlarged to the final size.
It was at this time that the only lives were lost on the project. A cave-in, caused by a high ground water level, resulted in the loss of four lives. The rescue operation was able to save eight other workers who were trapped with those that perished.
Tunnelling resumed after a delay of several months, and by 1971 the TBM was ready to commence work. A three-month trial period had been allocated to assess the suitability of the TBM for work at the western portal. It soon became apparent that the nature of the rock at this end of the tunnel was too fractured for efficient operation of the TBM, resulting in the cutters and fill extraction systems of the machine being continually blocked by rock. By the end of the trial period, the TBM had only advanced 106 m and was wearing out far more quickly than was hoped, so it was decided to dismantle it and move it to the eastern portal.
Work at the western end of the tunnel continued with traditional drill and blast methods. The profile of the western end, which had been round to accommodate the TBM, was changed to a horseshoe shape to better suit conventional tunnelling procedure. By the time the tunnel was finished, around 48% of the length of the tunnel had been bored using conventional methods.
Reasonable progress was made from the eastern end of the tunnel once the TBM had been reassembled there in April 1972. Though the wear on the machine caused by its use at the western end caused some mechanical problems, progress of up to 15 m per 8 hour shift was achieved, though this was considerably reduced in wet areas. With up to 600 m³ of water flowing through the tunnel walls, continuous pumping was required to avoid flooding.
Ducted ventilation was initially sufficient for the machine and the workers in the tunnel, but the closer the excavation got to the midway point, the more the temperature increased. To combat this, the shifts were shortened, though eventually three refrigeration plants had to be installed for the western end and one at the eastern end.
Completion
The two headings of the tunnel workings met on 4 June 1976 when two pilot tunnels were drilled through to the other side to check the alignment. Though the official hole-through ceremony had been planned for 17 June, the dignitaries had to be content with shovelling some of the rubble as the TBM had again jammed with loose rock. Mr. L. Dillon, a project supervisor, became the first person to walk the tunnel end-to-end on 21 June.The project plan had called for lining to be done once all excavations had been completed, but deteriorating rock, especially at the western end, meant that the plan had to change. The problem was solved by pumping concrete under high pressure behind steel liners. Once this was finished, the concrete track bed was laid by the private contractor Robert McGregor and Sons of the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
. Together with British Rail, they had developed a technique for laying paved concrete track (PACT). This method was chosen rather than the traditional ballast and sleepers to reduce maintenance costs for the track inside the tunnel.
Opening
The first official train through the tunnel was the Silver Fern railcar RM 3 which departed Hamilton railway station for Tauranga on 12 September 1978. On board were various railway officials and a party of 50 disabled Waikato school children.After a lunch stop at Matamata, Prime Minister
Prime Minister of New Zealand
The Prime Minister of New Zealand is New Zealand's head of government consequent on being the leader of the party or coalition with majority support in the Parliament of New Zealand...
Robert Muldoon
Robert Muldoon
Sir Robert David "Rob" Muldoon, GCMG, CH served as the 31st Prime Minister of New Zealand from 1975 to 1984, as leader of the governing National Party. Muldoon had been a prominent member of the National party and MP for the Tamaki electorate for some years prior to becoming leader of the party...
greeted the assembled crowd and boarded the train. The next stop was Hemopo, where a crowd had assembled. They were addressed by Piako County Council Chairman Mr. Thomas, the MP for Piako Mr. Jack Luxton
Jack Luxton
John Finlay "Jack" Luxton, QSO was a dairy farmer and New Zealand politician. He entered Parliament in 1966 as the National Party member for Piako and then, after boundary changes, Matamata. He represented the predominantly rural electorate for 21 years, to 1987.Luxton was a dairy farmer in...
and the Minister of Railways
Minister of Railways (New Zealand)
The Minister of Railways was the minister in the government responsible for the New Zealand Railways Department 1895–1981, the New Zealand Railways Corporation 1981–1993, and New Zealand Rail Limited 1990–1993...
the Hon. Colin McLachlan
Colin McLachlan
Colin Campbell Alexander McLachlan was a New Zealand politician of the National Party. A farmer by profession, he was the Member of Parliament for Selwyn 1966–72, Rakaia 1972–78, then Selwyn again 1978–81, when he retired....
. Then the Prime Minister gave a speech, and unveiled a plaque paying tribute to the four workers who had lost their lives. Finally, he cut a ribbon and declared the tunnel to be open. The train proceeded to Tauranga with the official party and minus the school children where several civic functions were held.
The project ended up running eight years over time, and over budget. The final cost was $43 million for the tunnel and $13 million for the deviation, a total of $56 million.
Today
Today, there are up to 22 weekday freight train movements per day through the Kaimai Tunnel, and up to 19 movements per day during the weekends. Freight transported over this route includes inter-port container traffic, timber and timber products, coal, manufactured goods, and petroleum.Traffic on the Kaimai Deviation has been dominated by freight trains for its entire working life. Regular passenger trains to the Bay of Plenty had ceased in 1967 with the final running of a post-Taneatua Express
Taneatua Express
The Taneatua Express was an express passenger train operated by the New Zealand Railways Department that ran between Auckland and Taneatua in the Bay of Plenty, serving centres such as Tauranga and Te Puke...
88 seater railcar
NZR RM class (88 seater)
The NZR RM class 88-seaters were a class of railcar used in New Zealand, known unofficially as 'articulateds', 'twinsets', 'Drewrys' and 'Fiats'. They were purchased to replace steam-hauled provincial passenger trains and mixed trains...
service; the lengthy and time-consuming route that the tunnel replaced was part of the reason this railcar service had ceased to be viable. It was not until 9 December 1991 that a regular service to the Bay of Plenty was re-introduced. Named the Kaimai Express after the tunnel, it ran between Auckland and Tauranga until its cancellation on 7 October 2001. For its entire existence, it was operated with Silver Fern railcars. Since the Railways Corporation relaxed its policy on private use of the national rail network in the 1980s, there have been occasional passenger excursions run on the deviation by organisations such as Mainline Steam
Mainline Steam
Mainline Steam is a New Zealand organisation devoted to the restoration and operation of historic New Zealand Railways mainline steam locomotives. Regular day excursions and multi-day tours are operated over rail lines throughout New Zealand...
and the Railway Enthusiasts Society
Railway Enthusiasts Society
The Railway Enthusiasts Society Incorporated is a New Zealand railway enthusiast society registered under the Incorporated Societies Act 1908 on 17 July 1958.-Objectives:The RES objectives are as follows:...
.
A peak of the Kaimai directly above the tunnel, previously unnamed, was named Stokes Peak in 2010 in honour of geographer Evelyn Stokes
Evelyn Stokes
Dame Evelyn Mary Stokes, DNZM was a professor of geography at the University of Waikato in New Zealand and a member of the New Zealand government's Waitangi Tribunal...
.