SANRAL poor culvert maintenance that cost 6 innocent lives

10 October 2017

The fatal storm that killed six people on the N3 in November 2016 was exacerbated by a blockage at one of the culvert inlets. A culvert is a structure that allows water to flow under a road. It led to water overtopping the embankments and spilling onto the N3, costing innocent lives. This was revealed in reply to a written Parliamentary question.

This incident is an indictment on SANRAL who are responsible for the maintenance of the culverts and our highways. Despite the already poor condition of the culverts, some of them have become living quarters for vagrants and were partitioned off and divided into rooms.

It is totally unacceptable that the situation was allowed to deteriorate to such an extent that it led to lives being lost.
I am calling for an investigation into this matter and ensuring that the person(s) responsible for the maintenance of the culverts face criminal charges. I have written to the South African Human Rights Commission requesting that they do an investigation into the matter.

According to the Parliamentary reply, SANRAL commissioned an investigation into the deadly floods which looked into the meteorological, hydrological and hydraulic assessment of the R24/N12, Linksfield and Gillooly’s interchanges to understand the underlying causes of the flooding. A final report was tabled on 12 September 2017 by the Investigating Specialist.

Emanating form the report is that the R24/N12 culvert system is inadequate to handle the recommended design of one in eighty year flood (1:80). The questions that I will be asking in Parliament is how was this allowed to happen and why the culverts were not upgraded at the time of the highway network upgrades, ahead of the 2010 world cup?
The report reflects on the event of 9 November 2016 and explores reasons for the flooding which occurred at specifically three sites:

- R24/N12 interchange

- Linksfield Road interchange

- Gillooly’s Interchange

From the conducted hydrological and hydraulic analyses the following can be concluded:

- The Linksfield interchange flooding can be attributed to the excessive high rainfall resulting in peak floods exceeding the hydraulic capacity of the drainage systems. A blockage at one of the culvert inlets further exacerbated the problem resulting in water overtopping the embankments and spilling onto the N3.The flow phenomenon was interesting and unexpected. In cases where debris however blocks a hydraulic structure flooding can occur.

- The median barrier in the case of the N3 flooding probably prevented further loss of life as it prohibited water from crossing the N3 which would have washed vehicles into the Little Jukskei River. It further resulted in the N3 north bound being accessible during the event and providing an escape route.

- The R24/N12 culvert system is inadequate to handle the recommended design flood (1:80). The inlet configuration, changes in catchment area and proximity of the commercial developments all played a role in the problems experienced at this site.

- Various scenarios have been analysed to find a workable solution for conveyance of the floods downstream. The suggested solution would be to provide an additional four 3 X 1.8m culverts underneath the R24/N12 and create a retention/stilling pond upstream, linking the existing channel to the new culvert system. The existing structure underneath the N12 consists of two 1.2 x 3.1m culverts. The situation here is that if the capacity of the culverts under the N12 is increased the houses on the northern side of the N12 is flooded. A rough estimate of the cost of these works is R30 to R40 million.

- Increasing of the capacity of stormwater conduits and the inlets at the Gillooly’s interchange is required to drain water from the freeway. The existing pipe system is made of 600mm diameter pipes and it is proposed to supplement them with a 900mm pipe. This needs to be jacked and a rough estimate of the cost is R4 to R5 million.

The recommendations of this report need to be further detailed and the proposed improvements need to be further developed, including detailed designs before it can be implemented. These improvements should be able to handle a 1:80 year rainstorm.

SANRAL needs to explain why the maintenance of their infrastructure was not done as a matter of urgency and they must also explain their plans to implement the recommendations of this report.

Issued by Michael Waters, DA Deputy Chief Whip in the National Assembly and Lethabong Constituency Head, 10 October 2017