Comparison: concrete vs. polycarbonate manholes

Occupational safety, installation time, operational organisation and resistance to environmental influences 

Polycarbonate manholes offer modern, efficient, and workable solutions for the cable infrastructure. They stand out in particular on account of their ease of use, excellent resistance, and versatility. They also provide for more efficient construction processes and reduced overall costs, particularly when compared with concrete manholes.

Weight and transport – quantitative comparison

A typical concrete manhole with clear dimensions of 800 x 800 mm and a height of 1000 mm weighs around 1500 kg (lower part + cover plate). By contrast, the weight of a Langmatz QaBo manhole with similar dimensions – QaBo 800 x 800 EK328, height 1060 mm – is just 91 kg for the manhole body and 241.5 kg for the concrete-lined steel cover, making a total of 332.5 kg. This equates to a weight reduction of approx. 75–80 % compared to concrete with the identical load class D400.

Installation consequences:

  • Installation is possible without the need for a heavy-duty crane; all that is required is a mini-digger and simple lifting equipment
  • More manholes can be installed by the same team each day
  • Lower risk of injury due to manual loads

An empirical study* on the installation of inspection manholes in sewer construction (211 daily data sets) showed significantly higher work productivity with polycarbonate manholes compared to traditional concrete and masonry models.

* Rezende Neto, O. S.; Souza, U. E. L. de; Sautchuk, C. A.: The Comparison between Plastic and Traditional Inspection Chambers under Labor Productivity Evaluation. São Paulo: Universidade de São Paulo, Escola Politécnica, 2004.

Predetermined breaking points – the straightforward way of dealing with pipes

  • The simplest and most professional pipe opening on the market, without adversely affecting the structural integrity
  • Prefabricated predetermined breaking points simplify installation, with fast and easy handling for all fitters
  • Predetermined breaking points are factory sealed – and are simply punched open on site
  • Standard predetermined breaking points are possible for pipes with DN 50, DN 110, and DN 160 mm

Overbuild frame – existing systems do not present a problem

  • Simply install manholes over existing systems
  • Frames with rectangular openings are used for the later installation of manholes on existing cable routes
  • Corresponding adapter plates are used to integrate media cables, as well as pipes and pipe bundles
  • Unused openings can be closed with closing plates

Occupational safety

  • Lower lifting loads reduce the risk of musculoskeletal disorders and accidents
  • Non-slip base plates (R10) improve safety inside the manhole
  • No need to drill the pipe openings
  • Optional, individual locking and closing systems prevent unauthorised opening and improve operational security

Benefits of polycarbonate manholes

  • Lightweight & easy-to-install – simple to transport and fast to install without the need for heavy equipment
  • Time- & cost-efficient – reduced construction times and lower overall project costs
  • Resistant – resistant to corrosion, chemicals, and moisture
  • Air-tight & secure – reliable protection against water and foreign bodies
  • Versatile – modular, simple to adapt and rework
  • Durable & low-maintenance – long service life with minimal maintenance
  • Technically beneficial – good insulation properties for additional cable protection
  • Sustainable – resource-conserving and frequently recyclable

Life-cycle costs – transferable knowledge

As there are no comparative studies for cable draw manholes, we are using the work of Shrestha et al. to assess the use of polycarbonate manholes compared to concrete manholes in the expansion of energy and data networks based on a life-cycle cost analysis. The following was derived:

  • The tested polycarbonate manholes have an average service life of over 50 years, while cement concrete manholes in the field often have to be replaced after approx. 20–25 years.
  • Life-Cycle Unit Costs (LCUC) of the tested polycarbonate manholes are significantly lower (approx. 10–20 % lower in a study*) because:
    • There is less damage
    • There is less need for renovation and replacement
    • Construction and waiting times are reduced

If you then transfer these findings to polycarbonate manholes (similar: highly resistant, factory prefabricated manhole body), it is technically feasible that, despite their higher procurement costs, PC systems are cheaper than concrete manholes over their service life, especially in networks with busy traffic where stoppages are extremely expensive.

* Shrestha, Keshav; Shrestha, Pramen P.; Batista, José: Evaluating Life-Cycle Unit Costs of Traditional Cement Concrete and New Polymer Concrete Manholes in Wastewater Systems. In: Buildings, Jg. 14, Nr. 9, 2024, Art. 2835. DOI: 10.3390/buildings14092835.