Culverts: an integral component for water, road and mining infrastructure projects

Culverts: an integral component for water, road and mining infrastructure projects

3 000 x 3 000 Rocla culverts in operation at the new Life style shopping centre in Wilgeheuwel

The main function of culverts is to manage the flow of water from one side to the other of an ‘obstruction’. This can be a road, railway track, trail or other structure constructed in either the natural or designed flow path of the water.

Factors to be considered before design and installation are the site specific application, environmental impact ensuring that erosion is minimised and structural damage avoided. Incorrectly placed or designed culverts can result in culverts failing, becoming dislodged and in extreme pollution cases being clogged with vegetation and sediment.

Rocla, one of South Africa’s leading precast concrete product manufacturers, is a supplier of a wide range of culverts for infrastructure and other water flow related projects. Their production experience and quality controls along with technical design expertise in project assessment and product design has been successfully utilised for custom designed culverts as well as many major infrastructure developments such as Polokwane Eastern Ring Road and the rehabilitation of the D528 in George’s Valley, Limpopo.

Culvert range

Along with custom designed culverts for once-off projects, Rocla offers two distinct ranges of culverts, differentiated by the type of loading requirements, both available with associated precast base slabs.

For heavy loading applications, such as to provide a waterway below railway tracks, Rocla’s SATS SAR Rectangular Portal Culverts can be used. These, or custom units are also utilised in any application with excessive fill requirements with the culvert tunnel at the base of the fill zone, allowing either conveyor or vehicle access.

The standard SAR culverts are supplied in lengths of 1,22 m and designed for up to 10 m of fill. Culverts required for loading heights greater than 10 m are handled individually and designed in-house at Rocla Head Office.

For traditional loading applications, creating waterways below roads, trails or even drainage channels, Rocla’s Standard Rectangular Portal Culverts are the preferred solution.

These standard culverts range in size from a span of 450 mm to 3 600 mm, and heights from 300 mm to 3 000 mm. The strength classes for these culverts are 75S, 100S, 150S, 175S and 200S.

If time constraints are a factor for any project, the precast culvert option, along with the precast base, as opposed to casting in-situ, will save on project duration and provide quality assurances on final product.

Wingwall units for culverts

Rocla’s precast Wingwall units can be used at both the inlet and outlet of any channelled system making use of circular or rectangular portal culverts for stormwater applications. The natural flow path of water upstream of a construction is often wider than the culvert or pipe structure. Transition sections are then required to receive and direct the flow of this upstream water through the culvert/pipe. The same is true of the downstream end of the culvert/pipe section. The precast concrete Wingwall unit is the most effective structure to use for the effective transfer of this water, eliminating erosion and creating a smoother flow of water.

Rocla manufactures a wide range of precast concrete products that are effective and cost efficient for all infrastructure and general construction projects requirements. The company has representation in Namibia and Botswana in addition to their South African presence.

Rocla is part of the ISG which also includes Technicrete

Efficient stormwater drainage solutions

Efficient stormwater drainage solutions

The Beany Block

Ineffective drainage causes a multitude of issues when areas such as roadways, parking lots, walkways and areas around buildings become swamped with large volumes of non-dispersing water. The Beany Block from Technicrete – a member of the ISG Group- is an efficient and practical solution for effective drainage due to its large flow capacity/unit weight ratio, making it a more cost-effective solution than conventional kerbing and drainage offerings.

The Beany Block system comprises a series of base blocks of standard channel section and Top Blocks of inverted channel section with an opening in one side face. When laid end to end they form a combined kerb and surface water drainage unit that is strong enough to withstand normal traffic loading.

Each standard top and base block is 500 mm in length and weighs approximately 85 kg.They have also been designed to withstand accidental 80KN axle loading. The top block oval openings provide for greater inlet capacities compared to conventional kerb inlets. Standard blocks can be used for curve radii of 30 mm or more. ‘Splay’ blocks are available to meet specific requirements with a radius of between 6 m and 30 m.


When the Beany Block system is utilised no long drainage sections are required to be specified in contractual documents. The system can be substituted for kerbs, stormwater pipework, kerb inlets and parts of footways. Damaged services are less likely to occur when installing the Beany Block due to its simple and practical design and installation.

Some of the traditional problems experienced with conventional drainage that the Beany Block system eliminates include: insufficient fall; conflicting levels of service mains and cables; ponding adjacent to low points; traffic safety and control on existing freeways.

Additional cost savings can be achieved on projects that have wide freeways and footways; freeways that have ‘flat’ longitudinal falls; rock in sub-grade; shallow outfall and existing services or foul drainage at conflicting levels.


The Beany Block has been designed for use in conjunction with SABS Fig. 3 and Fig.4 Barrier Kerbs. The Beany produces 400 mm length of inlet opening for every 1 m of kerb. The system can be used in any application where high inlet capacity is required; wide freeways; parking areas; taxi ranks and bus depots; wash bays and vehicle service areas; median islands; industrial areas; drainage around buildings and walkways and toll plazas.

Rocla’s Stormwater pipes

Effective stormwater management can prevent pollution, flooding, erosion and damage to the environment and infrastructure. Therefore, it makes financial sense for local municipalities to invest in products and technologies to ensure that the quality of infrastructure, be it stability and sustainability of both the built and natural environments is not compromised.

Within its range of products, Rocla – also a member of the ISG Group, manufactures stormwater pipes with both interlocking and spigot and socket joints in a range of strength ratings. The spigot and socket joints utilise the rolling rubber ring principal where no installation lubricant is required. All pipes conform to the SANS 677 standard.

After consultations with Rocla’s technical team, interlocking joint pipes were selected for installation at the Great North Plaza in Limpopo, whilst the Borwa project in Westonaria selected Rocla spigot and socket joint storm water pipes. Technical support from Rocla ensures that correct product and technology is selected with consideration for the financial constraints of each project.

Technicrete is part of the IS Group of companies which includes Ocon Brick and Rocla.