Lahti is small and green; the city centre is densely built (imperviousness approx. 65%). The current urban structure is largely inherited from the 1950s-1970s. Major transport routes almost cut through the city centre (Fig. A1). A motorway (E75) bypasses the eastern part of Lahti. Several smaller roads and railway routes intersect the city. In 2012, there were 80.4 km of main roads, 29.3 km of railway lines and 63.5 km of larger streets (streets considered in the noise mapping).
The E75 motorway affects the eastern part of Lahti. Traffic volume in Lahti’s city centre is high: about 20 000 – 38 000 cars on Main Road 12 (red square), 24 000 – 31 000 cars on Hollolankatu (left blue line) and 4 000 – 20 000 cars in the centre. The railway route in the city centre is actively used.
Traffic, and especially road traffic, is the most significant noise source (Figs. A2, A3). About 29% of the population is exposed to total noise values of Lden (day, evening and night noise level) above 55 dB(A) due to road traffic and about 4% due to railway traffic (Table A1). Noise pollution from industry is marginal. Only the Kymijärvi power plant causes significant noise pollution (the only IPPC Directive location). According to the noise mapping in 2012, approximately 100 residents were exposed to Lden levels above 55 dB (A) due to industry (Table A1) .
Although the city centre is noisy, many buildings (city blocks) in the centre have quiet courtyards. Excluding buildings that are partially located in more silent areas reduces the figures by approximately 1/3, but the true figures are somewhere in the middle.
There is no comparable earlier data for the 2012 noise mapping. In 2007, noise from the E75 motorway and Main Road 12 was mapped. In 2004, noise levels along the railway route were measured. In 2009, noise levels were measured for railway routes and city roads with traffic levels over 5 000 cars/day (located outside the centre). The latter study was updated in 2010. Based on that, about 1/4 of residents were exposed to noise levels above 55 dB during the daytime, of which half are in the city centre. Nearly 14 km of noise barriers should be built along roads and railways, costing approximately 20 M€. Lahti will receive results from a new noise mapping in late 2017.
Quiet areas were mapped in 2010 , for the Master Plan, and updated in 2016 (Fig. A5). Lahti has many quiet areas with high recreational value (e.g. large near-natural forests). Although the largest areas are located further from the city centre, smaller high-quality areas are easily accessible from the city centre. Since Lahti has abundant quiet areas, sites smaller than 2 ha were excluded from the mapping. A quiet area was defined as an area with noise levels lower than 50 dB during the day or less than 45 dB during the night. Altogether, 56 areas fulfilled the criteria. Essentially, noise levels in these areas are below 45 dB(A) or even < 40 dB(A). Quiet areas were divided into three classes: 1) quiet areas of especially high recreational or ecological value, 2) other quiet areas and 3) special areas. Lahti monitors the coverage of quiet areas every four years, in the master planning process.
Large and continuous forests on the Salpausselkä ridge reach into the centre and act as an important recreational area and quiet area (Fig. A4).
In 2015, 41.4% of the population lived within 300 m of quiet areas, but in reality the figure is much higher. Besides quiet areas smaller than 2 ha, and quiet areas visible on the map, lakes serve as quiet areas (Fig. A5) . During the summer, quiet locations on lakes are accessible by boat. During the winter, they are easily accessible by anyone. Fishing, skiing, skating and walking on ice are popular.
Reducing Noise Pollution and Preserving Quiet Areas
A Noise Abatement Action Plan was adopted in 2013 and is carried out by the Municipal Engineering, Land Use, Building Control and Environmental Services units [4, 16]. Measures for larger motorways and railways are covered in the Finnish Transport Agency Noise Abatement Action Plan . To lower noise levels, reduction of car traffic, in particular, is emphasised. A new Noise Abatement Action Plan will be drafted by July 2018. Noise issues are considered in Lahti’s Master Plan. A continuous, strategic master plan process with four-year cycles [6, 7] enables short-term adjustments to be made, if needed, e.g. in noise reduction.
Reducing Car Traffic
To lessen noise pollution, emphasis is on reducing road traffic, i.e. the source of the noise. The Noise Abatement Action Plan measures include:
Developing the city centre towards a pedestrian zone:
• Car-free zones in the city centre (Lanunaukio in 2007). (Fig B1).
• 2012 Development Plan for Walking and Cycling 2025 .
• In 2013-2015, a parking garage for 600 cars was built underneath Lahti’s market square and a number of parking spaces were removed from the streets. Reducing street parking increases the quality of urban space for pedestrians and enables development of the city centre towards a pedestrian zone (Fig. B2).
• Transformation of Aleksanterinkatu Street to a primarily pedestrian area, completed in November 2016 (cost 3.1 M€).
• Pedestrian paths are widened by taking space from cars (parts of Rautatienkatu and Aleksanterinkatu streets).
• Installation of additional bicycle racks, adding space for up to 1 100 bicycles.
• Speed limits are reduced to 30 and 40 km/h on some streets.
→ At least 4 000 fewer cars compared to the previous 15 000 cars per day (in 2011)
Promoting quiet transport modes and public transportation:
• A bicycle friendly city: 532 km of combined pedestrian and cycling paths (2016) [9, 10].
• In 2014, public transportation was reformed. New routes were added (40% increase in kilometres) and service frequency was increased.
• In 2015, 82.8% of residents lived in the pedestrian/public transportation zone (maximum frequency for public transport: every 30 minutes; maximum distance to a bus stop: 250 m).
• Lahti’s Master Plan concentrates on consolidating land use and ensuring a population density of at least 15 inhab./ha to enable good public transportation.
• A new Travel Centre was built in 2015  that combines the railway and buses for a smooth transition between the different modes, along with parking garages for bicycles and cars (investment 18 M€).
• The City of Lahti owns 3 electric bicycles and 8 electric cars.
• There are about ten public electric car charging outlets, more are planned.
• A test-ride of electric bicycles was arranged by the city, in 2016, for local companies’ workers and for residents (Fig. B3).
• Reducing speed limits close to sensitive areas (schools, residential areas) to decrease noise and increase safety.
As a result of these endeavours, Lahti’s residents are now using fewer cars and more bicycles (Fig. B4). Using public transportation should also increase, thanks to recent reforms.
Besides sound berms, Lahti has approximately 9.9 km of noise walls. These are mostly located by the E75 motorway and Main Road 12. Our Noise Abatement Action Plan includes constructing new noise barriers. New noise barriers are built to protect the most sensitive areas (e.g. kindergartens, schools, hospitals, residential areas) and the most noisy areas, as well as locations benefitting the largest number of residents.
• In 2016, construction of a new noise wall was completed on Tapparakatu Street (cost: 140 000 €), protecting a kindergarten and detached housing area (Fig. B5).
• Other planned noise walls (3 locations) will be constructed in Lahti during 2017-2018; detailed planning is completed or under way (see 6C).
2 in 1: Buildings as Noise Barriers
Constructing new buildings in locations with noise problems can reach two goals at once: 1) consolidating land use and 2) lessening noise levels by using the new buildings as barriers. Buildings are well insulated in Finland, so noise levels inside the buildings are very low. Apartment buildings are long and high, and function as a noise barrier protecting the areas behind it. For example, three long apartment buildings have been planned for Tapparakatu Street, with the first one already under construction. These buildings will reduce noise levels in the residential area.
Constructing in Noisy Areas
Noise issues are carefully considered before constructing. If there is a possibility of high noise levels, noise must be thoroughly mapped. Solutions to achieve noise levels below 55 dB are decided site-specifically, including measures such as soundproof windows, noise walls, and sound berms, or arranging buildings in such a way as to function as noise walls. If the property developer implements appropriate measures, the developer may receive benefits, such as a permit to construct more buildings on the plot. To consolidate land use and rehabilitate old industrial areas, we are developing brownfields, adjacent to the main railway route, as mixed-use/residential areas. These areas are subject to higher noise levels. Hence, noise must be carefully considered.
Noise levels have been modelled for the Hennala area. Due to noise pollution, buildings should be arranged in an L or U shape, to provide quiet areas. High-rise apartment buildings are recommended to protect areas further from the railway. It is advised that buildings closest to the railway be used for businesses. The City of Lahti arranged a competition to find the best planning solution for Hennala. The detailed plan was enforced in January 2017 .
Preserving Quiet Areas
The city is striving to, at least, exclude first class quiet areas from construction. It is possible to construct in other quiet areas, if sufficient quiet areas, in the area in question, are guaranteed to be preserved.
Communication with Residents
The noise mapping (2012) results and the Noise Abatement Plan were presented to residents, at a public event, in March 2013. Quiet area and detailed noise maps, along with the Noise Abatement Plan and noise reports are readily available on our website .
Lahti has been arranging an Environmental Week for 21 years. In 2003, the whole week was devoted to noise issues, and included seminars and walking trips. During the 2016 Environmental Week, a public event was organized where residents were able to learn about quiet areas and noise levels.
Noise Abatement Action Plan 2013-2018
The action plan aims to lessen noise pollution and to especially protect residents from loud noise (> 65 dB), highly populated areas, schools and kindergartens, and quiet areas.
Actions to reduce noise pollution:
A Noise Abatement Group monitors the implementation yearly. The plan is also updated yearly, based on the city’s construction programme and budget for the next year.
New Noise Barriers
Over the next two years, noise barriers will be constructed/improved on Kärpäsenkatu Street (close to Ahjokatu Street; estimated cost 80 000 €), Ahtialantie and Hirsimetsäntie roads (estimated cost 2.4 M€), and Helsingintie Road (estimated cost 100 000 – 175 000 €). Kärpäsenkatu noise barriers already have a detailed plan (Fig. C1). Sound berms are built in Nastola to protect residents from railway noise. All noise barriers will achieve noise levels below 55 dB. About 997 children and 623 residents/students will be protected when these barriers are built.
After constructing the abovementioned noise barriers, new ones are planned for other parts of Kärpäsenkatu Street (close to Kiekkostenkuja Road and Kaivotontinkatu Street costing 157 000 €, close to Harjunalustankatu Street for 179 000 €, and close to Okeroistentie Road for 147 000 €), Ahtialantie Road (close to Purorinteenkatu Street for 190 000 €) and Lahdenkatu - Mukkulankatu (Kivimaa School; 700 000 €). Noise barriers are also planned for the main railway route.
In new detached housing areas, space will be reserved for noise barriers, where excess construction soil can be used. The Noise Abatement Group has selected 10 preliminary sites where noise reduction will be managed through excess soil use, by 2021.
Quieter City Centre
Besides Aleksanterinkatu Street, other streets will also undergo a change (Figs. C2, C3) . Vapaudenkatu Street (adjacent to the market square “Tori” and parallel to Aleksanterinkatu) is being primarily developed for public transportation. Vapaudenkatu’s two-way high quality cycling path will be increased westward. Rautatiekatu Street (not highlighted on the map) will be further developed as a pedestrian zone. Most car traffic will be directed to a city centre outer “circle”, lessening traffic inside the circle. This enables additional cycling paths to be constructed (e.g. along Vesijärvikatu Street).
Noise Reduction in New Developments
The currently enforced detailed plan for a new residential area between the railway and Main Road 12 emphasizes noise control . The plan prevents traffic noise from reaching the south and railway noise the north. Noise protected blocks are placed inside the area.
Lessening Noisy Transportation
Lahti is committed to improving the already very good cycling network (Fig. C3). Campaigns will be organized to advertise cycling. We are currently benchmarking smart bike-sharing concepts and intend to create a sustainable test platform for these new service concepts. Lahti is planning to replace the current bus fleet with electric buses (long-term goal).
Constructing a bypass road (2018) will allow the direction of lorry transports away from the centre. The new road will be partially located in tunnels or below ground level. Noise barriers will be constructed along the rest of the highway in Lahti. Directing the Main Road 12 away from the centre enables Mannerheiminkatu Road (currently Main Road 12) to be developed into a normal city street (e.g. lower speed).
New Noise Mapping and Noise Abatement Action Plan
The new noise mapping will be completed in 2017 and will include the Nastola area. In Nastola, most of the population lives close to the motorways and the railway route. The new Noise Abatement Action Plan (2018) will include measures to reduce the number of Nastola’s residents subjected to high noise values. For example, additional noise barriers will be built by the railway.
A new evaluation on health effects of traffic noise (Case Lahti) is being done by Ramboll Ltd (consultant) in cooperation with the National Institute for Health and Welfare, and the results will be out in 2017.
Active Marketing of Recreational Possibilities of Surrounding Nature
Lahti has a high-quality nature environment with numerous recreational possibilities for enjoying peaceful, quiet time (Fig. C4).