A canal built in 1908 is renewed under a busy road in the centre of Budapest

On behalf of Fővárosi Csatornázási Művek Zrt., Colas Alterra Zrt. is carrying out the reconstruction of a 117-year-old sewer pipeline in the heart of Budapest, along a 225.5 m long stretch in Városligeti fasor from the Bajza Street manhole to the Lövölde Square manhole No. 4537144.

The pipeline served the area for nearly 120 years

According to Colas Alterra, the trunk canal on the border of districts VI and VII was built before the First World War, in 1908, during the Austro-Hungarian Empire. The blockages are the reason for the reconstruction of the Városligeti fasori network between the end of Lövölde tér Felsőerdősor utca and Bajza utca.
During the preparation of the project, with the help of the operator, the condition of the network was assessed - where the pollution allowed - mainly by means of cameras at the connections and by lighting the backbone lines with lamps.

The Wesselényi method to renovate the trunk canal

According to information from the contractor, the Wesselényi method will be used: the upper part of the existing sewer pipe will be demolished and the new, modern, 50.8/100 cm diameter, glass fibre reinforced polyester egg-section pipes will be inserted. This is because the narrower cross-section at the bottom of the pipe ensures good flow conditions for the drainage of waste water. While the wider, upper part of the pipe is able to quickly absorb large amounts of rainwater run-off.
This process allows the new pipeline to be built on the original track, while minimising
the environmental impact and the risk of utility collisions.

No-dig technology is used for work under the service roads

The laying of the pipe will be divided into three major sections - 40.5 m + 82.7 m + 65.4 m - for a total of 188.6 m with a gradient of 2.9‰.
As part of the construction, three monolithic shafts will be built, and a receiving shaft and the junctions will be upgraded.
Part of the works will be carried out using the open trench method, while the house connections under the service roads will be carried out using the "no-dig" method, i.e. without excavation, and partially soft lining.

How can all this be done in the middle of the city centre?

The Városligeti fasor is a busy traffic corridor with many schools and institutions, so the contractors had to work out a tight schedule and a traffic restriction plan consisting of several steps - especially during the summer school holidays.
The City League fascia was first completely closed for the asphalt milling work, then work will proceed in lanes, with the ridge line work first, followed by the odd- and then even-sided house
connections. Weather factors have also been taken into account in the planning, so that reserve times have been calculated.

Services will not be restricted during the works

For the people and institutions in the area, the key issue was not only the timing of the works, but also the need to avoid interrupting services during the reconstruction period.
In order to ensure continuous sewage disposal, the contractor will use a temporary transfer of the sewage via a fly line,
so that no restrictions are necessary.

Challenges above and below the surface

The project poses many challenges for the contractor's professionals. One of these is the constant traffic around the work site. The narrow working pit, barely 1.5 metres wide, where the 2.3 metre long pipe elements are lifted by the operators, an operation that tests their precision and concentration. All this with the trolleybus's flight line only one metre long, which they have to protect and pay particular attention to the safety of their colleagues.
Another difficulty is the presence of many inaccurately registered old utilities, which also poses a challenge for the contractors.

Work will be completed by the end of the summer

As a result of the reconstruction, the utility supply in the area will become more reliable and sustainable in the long term, while modern materials and technologies will reduce the need for future maintenance. The project is a good example of the importance of renewing the urban utility network, not only from a technical point of view, but also from a social and environmental point of view. The works are scheduled to be completed by the handover deadline of 31 August.