FAQ about the construction site

Work progress

Where can people get current information?

The easiest way is to follow the News page and the project’s Facebook page @laaksonyhteissairaalantyömaa

Where in the tunnel is the crew working at the moment?

You can follow the tunnelling crew’s progress on a map, which is updated weekly. The link to the map can be found at the bottom of the Construction sites page.

How does it look like on the site?

See live camera feed.

Why is it taking so long to build?

A lot of new things are being built in the Laakso hospital area. The new main building is the size of five Helsinki Central Librarys (Oodi). In addition to the main building, we are building a new hospital building for child and adolescent psychiatry, and the alliance is also repairing at least two protected hospital buildings.

Working hours

What are the working hours at the construction site?

See working hours.

We always tell you about changes and new work phases before they start, so that the neighborhood can prepare for the future. For the latest information, see the News on our website and/or our Facebook page.

Do we work at night?

As a general rule, work is not done at night.

Night work is only done if necessary and for justified reasons. Sometimes, for example, work done during the day would be a big inconvenience to traffic, so night work is the most reasonable option to reduce the inconvenience. The LYS project was worked at night, for example in the summer of 2022, when street work was done near the tram tracks.

Maintenance crews in the tunnel sometimes work night shifts, but no noisy works are carried out at night. For more information, see Working hours.

If night work has to be done, it will be announced well in advance on the News page and on our Facebook page (in Finnish).

What is the purpose of the 9-pm underground blasting slot?

The schedule has been designed to give enough time for the toxic fumes that are produced by detonating explosives to evaporate before our tunnelling crew resume work each morning. Late-night underground blasting also helps to speed up our open-face excavation and construction works. To ensure the safety of our crews, we evacuate the open-face excavation site and the construction site every time we detonate a charge. The tunnel also naturally has to be evacuated while blasting is taking place above ground, but the open-face excavation crew are not permitted to detonate explosives after 6 pm.

People notice the 9-pm blast more because there is less traffic in the neighbourhood in the evenings.

Read more: The 9-pm blast is the most noticeable

Disadvantages of construction

Does the construction cause vibration, noise or dust?

Yes it does. However, we do our best to reduce the inconvenience. The environmental authority of the city of Helsinki also issues instructions and regulations, the purpose of which is to regulate construction so that there is no unreasonable harm to neighbors.

Explosives from open pit mining and tunnel mining have different effects on the surrounding environment. In opencast mining, the explosions are fast and protective mats keep the loose rock tightly protected. In tunnel excavation, on the other hand, you have to allow time for the explosion. In a closed space, the stone expands and takes up more space, so it is forced to find its way into the free space of the tunnel. Because of this, the explosion is felt for seconds, even five seconds. An open pit explosion lasts only fractions of a second. Residents will probably notice the bangs of the tunnel excavation through the vibration of the building’s frame.

Read about how noise, dust and vibration are managed:

What noise control measures do you have in place?

The noisiest and most annoying stage of an excavation is the drilling, which is nevertheless crucial for getting the explosives into the rock.

Our crawler drill is fitted with a boom cover that significantly reduces noise levels. Without the cover, the noise from drilling would be many times louder. Most of the noise from drilling originates at the base of the drill where it enters the rock.

Listen to the sound of drilling:

Blasting is actually not a very noisy process. Each blasting operation consists of three steps:

• Each blast is preceded by an intermittent siren to warn our neighbors.
• The blast itself produces little noise – just a sound like a puff of air under the blasting mats.
• A continuous siren tone signals that the blasting operation has been completed.

Loading rock into dump trucks is another noisy process. The sound produced by a load of rocks suddenly hitting the truck bed can be startling. 

Our neighbors are most likely to suffer from noise at the start of the excavation phase. As we get deeper into the rock, the walls of the excavation will begin to act as a noise barrier.

What steps are you taking to reduce dust emissions from excavation works?

Drilling holes for the explosives is what produces the most dust during excavation.

At this stage of the process, we are simply using a dust catcher bag on our crawler drill to reduce emissions.

A vacuum system will be deployed as we get deeper into the rock. Our vacuum system consists of hoses connecting the crawler drill to a vacuum tank where the dust from drilling will collect. The tank will be emptied at regular intervals. The contents will be taken away separately and will not, for example, be dumped with the blasted rock. 

Some dust may escape from the base of the drill suction cup when the crawler drill is being operated. This can happen if the surface of the rock is uneven and it is not possible to achieve a proper seal with the suction cup. Most of the dust will still end up in the vacuum tank, however.

Blasting hardly produces any dust. A puff of air is released with each blast, but the blasting mats effectively contain the dust that this produces.

Dust can be an issue during rock loading. When the weather is particularly dry in the summer, we wet the rocks before loading. Wetting is not necessary in the winter when the rock is naturally damp.

How do you measure and control vibration?

We know from experience that what our neighbors find the most annoying about excavation works is the vibration. The human body is sensitive and notices even the slightest tremor.

Having a regular blasting schedule makes life easier for our neighbors. Blasting works at the Laakso Hospital construction site only ever take place at 9 a.m., 1 p.m., and 4 p.m. from Monday to Friday. There will be no blasting at other times.

We have also taken precautions to limit the inconvenience caused by vibration. The nearby buildings have been surveyed by a vibration measurement and mitigation expert. A risk assessment has been drawn up based on the results of the survey. The volumes of explosives that we use and the sizes of the blasting areas have been carefully measured so as not to damage the neighboring buildings.

We have also installed vibration sensors in the nearest buildings, which allow us to monitor vibration levels in real time after each blast.

The detonators that we use on the Laakso Hospital construction site are ultra-modern digital ones that are accurate to a millisecond. This degree of control over the detonation time significantly reduces vibration. The explosives that we place in the blast holes are not detonated all at once, and instead we deliberately stagger them slightly so as to effectively “slice” the rock. This means that the vibration that our neighbors feel is not from one single explosion but from a series of smaller ones that are staggered at intervals of a few milliseconds. This technique cuts vibration levels to a fraction of the maximum.

You say that there is no danger to buildings, but there seems to be a lot of vibration. Why?

The noise and vibration caused by blasting can travel long distances in the bedrock. The human body is especially sensitive to noises and vibration that are not part of the normal soundscape. People living near railways experience similar noises and vibrations from passing trains. Each individual has a different sensitivity to vibrations. Most people are able to sense even very low levels of vibration and can find these alarming especially when indoors.

We do our best to minimise the inconvenience by, for example, sticking to our carefully thought-out blasting schedule.

Read more: Vibrations and noise from blasting can travel long distances in the bedrock

Neighborhood

How much extra traffic will there be in the neighborhood due to the construction works?

We are building a temporary access road to the construction site from Auroranportti on Nordenskiöldinkatu, which will allow construction vehicles to enter the Laakso Hospital area via the Laakso riding arena. The new site road will reduce traffic volumes on Lääkärinkatu and Urheilukatu and help to alleviate congestion in the Laakso and Töölö neighborhoods.

What is happening with the Laakso riding arena?

The riding arena is part of the construction site. Once the works in the hospital area have been completed, the riding arena will reopen as before.

What is happening with the Auroran kenttä parking lot?

We have unfortunately had to close the Laakso parking lot to make way for the construction works. The developer has provided alternative parking spaces for the general public and especially hospital staff elsewhere.