Humps too high?

Sybil Nieuwoudt and Johan du Preez measuring the humps
Sybil Nieuwoudt and Johan du Preez measuring the humps

Leoni Kruger
LEPHALALE — Following a previous article in the Mogol Post “Speed bumps (humps) too high?” in the 12 February 2016 edition, Mogol Post received an overwhelming amount of calls from motorists complaining that the municipality is providing an incorrect information regarding the speed humps in Lephalale.
The height and length of the speed humps in Lephalale are not according to the dimensions as indicated in the Department of Transport’s COD report, CR-97/038: Design and Implementation of speed humps: Supplement to National Guidelines for Traffic Calming.
The mentioned report states that local and overseas research has indicated that the ideal speed hump should be approximately 3.7 m in length and between 7cm and 12cm in height. If shorter, they are too severe and if longer they are too easily negotiated by typical passenger cars.
Mogol Post took to the streets of Lephalale, together with Sybil Nieuwoudt in order to measure the humps which some motorists are unhappy about.
In Waterbok Street in Onverwacht one of the humps was 14 cm high on the one side and 10 cm high on the other side. The length of this hump was 1.56 m.
In Walter Sisulu Ave one of the humps measured 6 – 7 cm in height and 2 m in length. In Gruis Avenue, a hump measured 7-8 cm in height and 1 m in length.
According to the above mentioned COD report, speeds humps, particularly in isolation, are not suitable on roads carrying high volumes of traffic. “One of the main problems associated with speed humps is their varied effect on various sized vehicles. For instance, a normal 3.7 metre long 100 mm high round top speed hump will be far more severe on a bus or a service delivery vehicle than on a passenger car, having the equivalent effect of a smaller speed bump on a normal passenger car” the document stated.
The document furthermore states that careful attention should be paid to motorists regarding the presence of speed humps. The warning signs are provided by the SA Road Traffic Signs Manual. “Road markings should be with high quality retro-reflective paint with good skid resistance properties. It is also recommended that the speed hump warning sign be used in combination with an Advisory speed sign (mounted immediately below the warning sign), showing the appropriate speed for the specific hump. The traffic sign should be placed 30 metres ahead of the speed hump. Mogol Post could not see any warning signs or speed advisory signs placed 30 metres ahead of any of the mentioned speed humps in Lephalale.
It is essential that motorists are able to see the speed humps well in advance and it is also essential that adequate lighting is provided so that the speed humps are sufficiently visible at night. Some of the hump’s paint is so faded that it can not be distinguished from the rest of the road.
Regarding the construction of the speed humps, the document stated that it is “essential during the construction phase that adequate inspections of the works are carried out to ensure that the speed humps are accurately constructed to the correct dimensions and spacing. Particular attention must be paid to signing, marking and drainage”.
Then it is important to monitor the effects of the speed humps on traffic flow characteristics, whether to see if the implementation of the humps achieved the desired objectives.
According to Johan du Preez, a resident of Lephalale, he cannot cross a speed hump in Lephalale without damaging his car. According to research done, he says that the ground clearance of every single car differs. For example, the ground clearance of a Jaguar is 110 mm compared to a Volvo 560’s ground clearance of 136 mm. The ground clearance of a VW Jetta is 159 mm. These are only examples to prove his statement. The grooves on all the mentioned speed humps are a clear indication that many cars battle to cross most speed humps in Lephalale.
Mogol Post asked the following questions to Rudzani Ngobeli, Manager Public Works at Lephalale Municipality:
MP: Does the municipality have technical designs for the construction of the speed humps?
LM: Yes, we are using standard designs as set out by the Road Agency Limpopo.
Our speed humps are generally the right height (between 7 and 12 cm). The reason why speed humps in Lephalale are 2 m in length has to do with the amount of material needed to construct a speed hump with a length of 3 m. The material is earmarked for the patching of pot holes and what is left will be used for speed humps.
MP: Is there a mould or something that they use to ensure that the humps are constructed according to the regulations supplied by the COD report? And all of them are the same height and length?
LM: No we are not using a mould.
MP: Do they work according to a traffic calming master plan?
LM: We do not currently have a traffic calming master plan in place. We are however guided by national as well as provincial standards which stipulates that speed humps be erected at school crossings, hospitals etc. We also take into cognisance complaints by the community relating to safety of residential areas, the rate of accidents also play a part.
MP: What is the extent of public participation in this regard?
LM: We invite comment from the public even though this is not done during a formalised public participation meeting. Members of the public will request a speed hump in a certain area and the Municipality will investigate the viability of such.
MP: Why are there no advisory speed signs?
LM: When we erect a new speed hump accompanying advisory speed signs are also erected. Over time these signs are either vandalised or damaged. We do realise that there are areas where we need to replace advisory speed signs and will do so in due course.

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