The renovation of the Balaton water control gate has been recognised with a professional award

The modernisation of Lake Balaton’s drainage system was carried out on behalf of the National Water Authority, based on the VIZITERV Consult Kft. plans; the construction work was carried out by STRABAG Építőipari Zrt. and the Colas Alterra Zrt. consortium.

The project had previously won the jury prize in the public space category at the Archello Awards 2025 international architectural competition, and prior to that, the Hugó Lampl Memorial Plaque was also awarded to Gergely Kiss, the project leader of STRABAG, and his team for their professional work.

A systematic response was required to the extreme water levels

Since the 2000s, water levels in Lake Balaton have become increasingly extreme: both persistently low water levels and periods of heavy rainfall pose a serious challenge to the lake’s environment, the areas along its shores, tourism and water management. The solution has been a comprehensive modernisation of Lake Balaton’s drainage system.

Not one, but three structures play a role in regulating the lake’s water level: a navigation lock, a drainage lock and a weir. These had to be rebuilt in such a way that water level regulation was continuously maintained via at least one lock throughout the construction period.

Not only was a lock built, but the entire water management system has become more flexible

The aim of the project was to make water level regulation in Lake Balaton safer and more flexible. Due to the effects of climate change, it has become a priority to ensure that more water can be stored in the lake during wetter periods, whilst reducing the likelihood of persistently low water levels during drier periods.

Ensuring safe conditions for maintaining a higher water level required not only the replacement of three structures, but also the coordinated development of several sections of the Sió Canal. Water management experts considered it appropriate to raise the previously applied maximum water level of +110 centimetres to +120 centimetres; to achieve this, the sluices had to be adapted to retain an additional 60 million cubic metres of water.

The water level control sluice at Siófok has been completely rebuilt

The main facility for draining water from Lake Balaton is the water level control sluice at Siófok. During the works, the original structure was completely demolished and replaced with a new 2×8-metre open-channel sluice, which is capable of operating at a water conveyance capacity of 80–100 cubic metres per second.

A new navigation lock has been built alongside the water level control lock. Its purpose is to facilitate the passage of vessels between Lake Balaton and the Sió Canal; it can also be used as a secondary discharge lock. As a backup facility, it enhances the operational reliability of the entire system.

A temporary bridge ensured traffic flow

As part of the construction work, the Balatonkiliti weir was also renovated. One of the unique aspects of the project was that the BAHART site could only be accessed via the construction site itself, so a temporary bridge was erected to ensure uninterrupted traffic flow.

The scale of the project is illustrated by the fact that 670,000 cubic metres of earth were moved and 19,000 cubic metres of concrete were used during the works. The project also included the dredging of the riverbed on both the left and right banks of the Sió Lock. At Bogyiszló, near the Keselyűsi navigation lock, a new submerged debris deflector wall was constructed to help divert debris towards the Sió Floodgate.

The embankments have been relocated along a section of the River Sió

As part of the project, the embankments on the left bank of the Sió, upstream of the Kölesdi Bridge, were relocated between kilometre markers 36+190 and 43+670. The main flood defence line was constructed mainly from material from the existing embankment and, to a lesser extent, from material obtained from the restoration and dredging of the Sió riverbed.

Over a 1,020-metre stretch on the right bank of the canal, dredging works were carried out: flood defences were constructed from the material removed during dredging, and existing defences were raised. The restoration of the riverbank on the right bank of the Sió Canal was also completed. This was an urgent task not only from a flood protection perspective, but also because a section of the embankment bordering the public road had collapsed into the canal, and further landslides would have endangered the integrity of the road surface.
The comprehensive renovation also involved seven culverts, as well as a sluice gate and a water lift. The service bridges over the Cinca-Csíkgát and Kiskoppány streams underwent complete reconstruction, whilst the service bridge over the Fenéki-Bozót ditch was demolished.

The development also takes wetland habitats into account

The second phase of the project focused on managing the spring-fed wetlands along the River Sió. River dredging and sedimentation basin construction works took place between Siófok and the mouth of the River Kapos.
Opportunities arose to create approximately 130 hectares of wetland habitat on the outskirts of Balatonszabadi and Siójut. A lake system was created in the deltas of the Sió and Kapos rivers, providing a habitat for numerous rare animal species, such as the black stork.

Drainage had to be ensured even during the construction work

According to Gergely Kiss, project manager of STRABAG, the greatest challenge of the project was the need to maintain the option of draining the water even whilst construction was underway. The work was made more difficult by the presence of water from the outset, whilst it was also necessary to ensure that the water could be drained if required. Drainage was required on five occasions during the construction period; these could not be carried out on a scheduled basis, but were dictated by the current hydrological conditions in each case.

A particular challenge was the need to complete work on the Sió Canal and the lock six months ahead of schedule, so that BAHART’s new catamarans and ferries could be launched via the canal. At that time, the manoeuvrability of the lock’s moving mechanisms was ensured by a temporary control system, and, unusually, the operation had to be carried out using only the ship lock.

For the specialists at STRABAG, the experience gained in detailed solutions relating to hydraulic engineering was one of the project’s most significant benefits. These included the design and construction of work area boundaries within the riverbed, the dewatering of work pits, the construction of sluices and sluice-operating equipment, and the installation of a complex control system.

It took two thousand working hours to create the special exposed concrete finish

Looking at the project as a whole, Gergely Kiss highlighted the new operations building as a successfully completed technical challenge. Among the many construction challenges, one of the most interesting was the creation of the pigmented concrete façade with a hairline texture.

According to him, producing the approximately 40 cubic metres of exposed concrete took around 2,000 working hours. This included sample preparation, trial mixing, selecting the colour and finish, developing the concrete technology, the involvement of the mixers and the batching plant, as well as the formwork and concreting work.

The contractors also visited Krisna Valley after learning from one of the concrete manufacturers that they had produced similar concrete there. In the end, only Frissbeton’s concrete plant in Székesfehérvár agreed to take on this unusual task.

The award also highlights the role of engineering in the public interest

The plaque for the Construction Industry Quality Award commemorates this superbly executed project. At the unveiling ceremony, Ernő Wagner, President of the Hungarian Chamber of Engineers, emphasised that the world of water management infrastructure has finally received the attention it deserves from a wider public, beyond the professional community. As he put it, the Sió Lock project has an impact on the water systems, economy and life of an entire region, which also demonstrates that engineering work is in the public interest. He emphasised that the engineering profession must speak out much more forcefully on issues of environmental protection and water management, and make it clear that technical interventions are carried out with respect for nature. The organisation’s president highlighted:

„A good work of art is not a foreign object in the landscape, but a meaningful part of it. It is through such works that we can restore the prestige of the engineering profession and demonstrate that their work serves the public interest.”

Sándor Vermesy, curator of the Construction Industry Master’s Award Foundation, said in his speech: “This award is presented by the profession to the profession, which is why it is a particularly significant honour.” He recalled the history of the Construction Industry Quality Award and the Construction Industry Master Award, spanning more than three decades, emphasising that the award has managed to remain free from political influence and does not come with a cash prize. He concluded his speech with best wishes, expressing his hope that sufficient rainfall would reach the Lake Balaton catchment area. He also expressed his hope that the changes currently taking place in the country would once again enable the success of those in the construction industry to depend primarily on competitive and high-quality work.

During the ceremony, the subcontractors involved in the project were also welcomed and presented with awards. At the event, Antal Piukovics, CEO of Colas Alterra, and Kornél Csordás, project manager at Colas Alterra, received commemorative medals.

A modern solution to the water management challenges of the future

József Gacsályi, Deputy Director-General for Technical Affairs at the National Water Authority, says that the award recognises professional achievement that is deeply rooted in the traditions of Hungarian water management, whilst also providing modern solutions to the challenges of the future.

He emphasised that the regulation of Lake Balaton’s water system, which began in the second half of the 19th century, has undergone significant changes to the present day. Instead of rapid and controlled drainage, an integrated approach is now the norm. Extreme hydrological conditions, which are becoming increasingly common as a result of climate change, demand flexibility and foresight, and this requires reliable infrastructure.

Imre Etl, head of the STRABAG division, recalled that the work was hampered by the Covid-19 pandemic and supply chain issues caused by the Russia–Ukraine war. Ensuring transport for BAHART posed a challenge, as did the fact that part of the work site had to be handed over earlier than planned due to the arrival of the new ferries. Transporting the 27-tonne lock section from Debrecen to Siófok was also a complex task.

He emphasised that Colas, STRABAG and the investor had carried out this complex project through exemplary cooperation, drawing on their own value-creating capabilities. Imre Etl also expressed his special thanks to the manual workers. As he put it:

„The Quality Award is not a cash prize, but rather a reward for the high-quality work carried out by everyone involved.”