Vibration and structure-borne noise effects of the Airport Line assessed with unique precision

The planned Airport Line is a new 30-kilometre rail connection from Pasila via Helsinki Airport to Kerava. The Airport Line enables direct long-distance train connections to the airport from large cities in the regions, and it reduces travel time from Helsinki city centre to Helsinki Airport by up to fifteen minutes.

The travel time of long-distance trains coming to the airport from the directions of the main line and Lahti will be reduced by 20–24 minutes. The Airport Line will also increase the rail capacity in the main line, since part of the traffic will be transferred to the Airport Line, improving the flow and reliability of train traffic throughout the country.

The Airport Line project, which has progressed to the general planning stage, is being promoted by Lentorata Oy. The company is owned by the state and the cities of Helsinki, Vantaa and Lahti and tasked to design the new railway connection up to a point where it is ready for construction.

– The Airport Line will bring new urban areas less than three hours away from Helsinki Airport and connections to the world. It reduces the travel time of all trains coming from the main line to the airport, whether departing from Oulu or Tampere. A direct and faster connection to the airport will also be created from the direction of Lahti. With the new track capacity, the Airport Line will also make it possible to increase the number of commuter, urban and long-distance traffic services during peak hours, says Siru Koski, Planning Director at Lentorata Oy.

The new line will mainly run in a tunnel, which will be the longest railway tunnel in Finland at 28 kilometres. The Airport Line is located in four municipalities: Helsinki, Vantaa, Tuusula and Kerava.

Impacts of the line assessed property by property

The effects of the future railway line on the environment and nearby residential areas are studied carefully during the design of the Airport Line. At the moment, soil and bedrock surveys, are being carried out as part of the master plan phase.

– The further the planning progresses, the more we know about the environmental impacts of the line. In the EIA phase, structure-borne noise was identified as the most significant impact during operation, and we are now studying it in more detail with the help of a modelling tool. The area impacted by the Airport Line is large, and it is important for us to know how the different areas are affected, so that we can determine the right technical solutions to reduce the structure-borne noise. Already with the current initial data, the modelling tool has contributed greatly to this, says Koski.

Timo Huhtala from AINS Group and Siru Koski from Airport Line explains how Vibmapper can be used to analyse the effects of structure-borne noise on a property-specific basis.

The impact of structure-borne noise on buildings along the Airport Line is being studied with a digital application, Vibmapper, developed by AINS Group. Globally, the application is unique in rail transport projects. The algorithm-based software models the effects of rail traffic throughout the impacted area very accurately.

– With this technology the effects of structure-borne noise can be assessed separately for each property. This allows us to identify the noise-reduction solutions required for each property and prevent the disturbing effects very cost-effectively, says Timo Huhtala, Business Unit Director at AINS Group.

Rail traffic produces structure-borne noise in the soil and bedrock, i.e. vibration in the soil and building structures. Indoors, it manifests itself as low-frequency noise. Usually, structure-borne noise analysis and assessments is carried out with spot checks. AINS Group's Vibmapper extracts property and soil data from open data, calculates the impacts of rail traffic in different traffic situations and visualises the results on a map template.

With the property-specific results, the measures to prevent and control structure-borne noise can be targeted and selected carefully in relation to costs and benefits.

– For example, in several new railway projects, alternative ways of implementing the railway have resulted in significant savings, says Huhtala.

– The further studies and plans for the Airway Line will be targeted carefully on a resident-oriented basis without forgetting the economic aspect, adds Koski.

Further information:

Siru Koski, Planning Director, Airport Line Ltd
tel. +358 40 723 2044
siru.koski@lentorata.fi

Timo Huhtala, Business Unit Director, Acoustics and AV technology, AINS Group
tel. +358 40 643 3762
timo.huhtala@ains.fi