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A direct approach to a direct line

Posted: 31 May 2006 | Juha Kansonen, Project Manager, RHK | No comments yet

The major Finnish railway direct line project from Kerava to Lahti will be completed on 3 September 2006.The direct line is the most important railway project in Finland for over two decades and new technical solutions have been introduced with the guidance of the Finnish Rail Administration (RHK),who is responsible for the project.

The major Finnish railway direct line project from Kerava to Lahti will be completed on 3 September 2006.The direct line is the most important railway project in Finland for over two decades and new technical solutions have been introduced with the guidance of the Finnish Rail Administration (RHK),who is responsible for the project.

The major Finnish railway direct line project from Kerava to Lahti will be completed on 3 September 2006.The direct line is the most important railway project in Finland for over two decades and new technical solutions have been introduced with the guidance of the Finnish Rail Administration (RHK),who is responsible for the project.

The Kerava to Lahti direct line is part of the ‘Nordic Triangle’ which is one of the 14 primary TEN projects. The Nordic Triangle is a transport system of different modes which links the capital cities of the Nordic countries to each other and provides connections between the EU and Russia. The direct line will increase rail capacity to eastern Finland and Russia and reduce the traveling time from Helsinki to Lahti from 82 minutes to 44 minutes. The traveling distance is reduced by 26km.

Shifting traffic to this line will also make it possible to make better use of capacity on the main line from Helsinki to the north via Tampere. The line will mostly follow the same route as the Lahti motorway, limiting the environmental effects of transport to a single corridor. The line will diverge from the main line Helsinki-Tampere just after Kerava and connect to the Riihimäki-Lahti line approximately 10km west of Lahti.

The Kerava-Lahti line will be double-track, electrified and equipped with automatic train protection.With a total length of 74km, including 63km of new track, the line will have no level crossings and will be used for both freight and passenger traffic. There will be two intermediate stations at Haarajoki and Mäntsälä. The maximum speed on the direct line will be 220km/h for tilting trains and 160km/h for other passenger trains.

Based on the initial design of 1998, the project budget has been set to !331 million. The main provider of funds is the Finnish government, but the project also receives funding from the EU.Annual funding has been set according to project requirements instead of preallocated annual limits. It is planned that the operator should pay an annual investment fee which would cover a part of the investment costs.

Project management

The direct line has been built using a project management consultant, with design and construction divided into subcontracts. The project management consultant assists RHK to select, supervise and co-ordinate design consultants and contractors.All contracts are concluded directly between RHK and consultants/contractors. The project management consultant is paid by the hour and has no financial risk over the project.Working parallel with the project management consultant is another consultant who is responsible for the design control and technical approval of documents once the project management consultant has focused on costs and schedule.

Procurement is according to directives on public works/service/supply contracts.All public tenders exceeding specific contract values have been published in the supplement of the Official Journal of the European Union and published throughout the EU. The total number of contracts awarded is approximately 320.

Design contracts

The construction of the direct line was preceded by years of planning. The most important studies and decisions related to the project include:

  • A study of rail requirements in eastern Finland (1992)
  • A project decision (1994)
  • A tentative general plan and environmental impact analysis (1996)
  • A general plan for the direct line (1998).

Funding was confirmed in June 2001 and was followed by a permit to start field studies in July 2001. The project management consultant was chosen in September 2001.

The first design task after the project start was to revise the basic design that was completed in 1998. In order to minimise the time required, this task was divided into two sections; the southern section from Kerava-Mäntsälä and the northern section from Mäntsälä-Hakosilta. Revision started in autumn 2001 and was complete in spring 2002. The detailed designs of five major bridges commenced simultaneously in winter 2001-2002.

The revision had three main objectives:

  • To optimise the use of excavation masses
  • Confirm the €331 million budget
  • To determine the number and scope of main contracts.

Special computer programs were used to calculate the most cost effecient elevation for the direct line. Savings were pursued also by changing the position of the direct line’ thus avoiding construction of two bridges.

Schedule and construction

The permit to start redeeming land was granted on 18 April 2002, which was the kick-off for the actual construction works. Clearing of redeemed land began in the summer of 2002 and the first substructure construction contract was signed on 1 November 2002, one year after the revision of the initial design began. During the following year, 19 other substructure and bridge contracts were signed. Most of the early contracts were in the section of Mäntaälä-Hokosilta, since superstructure works were planned to take place in two phases: form Hakosilta to Mäntsälä in 2004 and from Mäntsälä to Kerava in 2005. The Finnish weather has its role in the construction schedule, since works slow down significantly for cold winter months between December and March and begin with full force when ground frost is over.

Other major construction contracts include stations, electrification, interlocking equipment and noise barriers. New techniques and ideas Being the first new railway line in Finland for over two decades some new technical solutions have been introduced on the line:

A new railway junction bridge

The Kytömaa railway junction bridge is located in Tuomala, where the western track of the direct line crosses over the two tracks of the main line Helsinki-Tampere. The surrounding area is flat, open farmland and conventional bridge designs were not approved by local communities or landowners who instead preferred a massive 1,300m long concrete culvert under the main line. The angle of crossing the main line slants significantly, so a particularly long span width of 58m is needed for crossing over two tracks. On the other hand, it was important that in the junction point the level of the crossing line can be taken as low as possible due to the railway line gradient and environmental requirements. A stressed concrete trough bridge was introduced for this purpose. The total height of its superstructure is 3.3m but the structural height below the track only 1.35m. The trough beams constitute 1.95m high noise barriers at both sides of the track.

In order to assist communities´ decision making, a 3Dvirtual model was made of the bridge and of the surrounding farmland. Topography of the direct line was laser scanned from helicopter in the beginning of the project, which made it relatively easy to produce the 3D-model. Using the model, authorities and landowners could virtually move around and above the bridge and even take a look at the bridge from their own home window.With the help of this 3D-model the bridge alternative was chosen. Being €16.5 million cheaper than the culvert, this was one key factor to guarantee that the original budget would be met.

Rail movement joints

When the length of a bridge exceeds 100m and the thermal expansion combined with train braking forces causes movements over 50mm, a rail movement joint is required. Total purchasing and maintenance cost of this equipment is approximately €400,000 over its product life cycle. In three cases this cost could be avoided. Instead of making one long bridge, two smaller bridges were constructed at Rööpakka Railway Bridge.At Lukkokoski, the massive abutment normally at the end of a 150m long bridge was made to the centre of the bridge, thus limiting the movement to two 75m long sections. Thirdly, one 251m long bridge was replaced with piled slab structures and high embankment on top.

Standard underpass design

The increased 35t design requirement for axle loads on bridges and pile plates meant that old standard bridge designs for 25t axle weights could not be utilised. Therefore, the basic design for underpasses and pile-slab foundations started in spring 2002. The same standard slab frame design was then used in all seven detailed design contracts.

Heavy tamping and deep mixing

Two new construction techniques were used for the first time in railway construction in Finland: deep mix-stabilisation and dynamic compaction (‘heavy tamping’) were used instead of pile-slab foundations. Dynamic compaction was used with very deep cut and fill excavations where groundwater level was above the bottom of excavation. The structure is cheaper than the originally planned pile-plate foundation and does not require any maintenance. Since the line had excess rock masses, the use of cut and fill excavations compacted with heavy tamping was also an environmentally friendly solution.

Deep mixing was used for the first time in railway construction in Finland, not for improving stability, but to accelerate the settlement when used with overburden. A new cement type made it possible to achieve sufficient strength to cement pillars to allow the use of required overburden.

Project status: spring 2006

The Kerava-Lahti line is an unusual infrastructure project; since the progress has been according to schedule and the original budget will be met. The most hectic year was 2004, when superstructure works began from Hakosilta, while substructure works were still ongoing in most of the direct line. During 2004, €127 million was paid to contractors and during October 2004, over €1 million was paid to contractors each day.

Commissioning of interlocking equipment, automatic train protection system and electrification started in March 2006 and will be completed by May 2006. That will be followed by high speed tests, load tests, final tamping and grinding of rails which shall all be completed by 3 September 2006, when commercial traffic begins.

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