MOSSEL BAY NEWS - Scant regard seems to have been given to the environment and to the effect of air pollution when additional speed bumps were built on roads in Mossel Bay neighbourhoods.
Research by Lethabo Air Quality Specialists (LAQS) indicates that road calming measures such as speed bumps negatively impact the ambient air quality.
Chemical engineer Chris Albertyn is the owner of LAQS, the consultants appointed to review the air quality management plan of the Garden Route District Municipality and the B-municipalities in its jurisdiction.
Stop/start effect
Based on European Union Standards, research results by Albertyn indicate the stop/start effect of speed bumps on vehicle emissions may result in unnecessarily higher - and largely avoidable - levels of air pollution in residential areas.
Albertyn argues that several other mitigating traffic calming measures are available that result in much less of an effect on the environment.
The EU Emission Factors indicate the emissions of slow moving vehicles are generally higher than when at speed. This is due to internal engine combustion efficiencies which result in more efficient fuel combustion at higher speeds.
The problem is exacerbated during stop-start driving conditions, which are enforced by speed bumps. Vehicle emissions typically consist of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM), carbon dioxide (CO2) and Methane (CH4).
The levels differ for the various types of vehicles, the type of fuel and the speed travelled.
Most notably the emission levels at low speeds such as five km/h - such as when motorists stop at or accelerate from speed bumps - far exceed those at higher speeds, typically the 60km/h speed limits in residential suburbs.
Speed bumps versus stop streets
Stop and yield signs are obvious and important traffic regulators necessary for order and traffic control. The question is whether copious numbers of traffic bumps in specific streets are the most desired traffic calming measures in residential areas, and especially in conservancies, where the emphasis is specifically placed on the wellbeing and vitality of residents and a balanced ecosystem. Are mini-circles and stricter speed enforcement not more effective countermeasures, even if more costly in the short term?
In an interview with the Mossel Bay Advertiser, Albertyn emphasised the pollution effect of petrol versus diesel sports utility vehicles (SUVs). The emission levels of carbon monoxide, for example, are markedly higher at very low speed for all petrol SUVs compared to diesel SUVs - both increasingly popular types of vehicles.
Diesel light motor vehicles have by far the least level of CO emissions. Likewise, diesel delivery vehicles travelling at a slow speed have an even more pronounced effect on air pollution.
Recent research by the Automobile Association suggests that 37% of South African motorists indicated they still prefer diesel vehicles over petrol vehicles despite recent studies showing that thousands of people die prematurely as a result of diesel engines exceeding their stated emissions standards.
Carbon monoxide (CO) is a colourless, odourless toxic flammable gas formed by the incomplete combustion of carbon. The natural concentration of carbon monoxide in air is around 0.2 parts per million (ppm), and that amount is not harmful to humans. As CO levels increase and remain above 70 ppm, symptoms (headache, fatigue, nausea) may become more noticeable.
Like carbon monoxide, hydrocarbon vapours may have negative health effects.
Carbon dioxide is always released when hydrocarbons are burned. Carbon dioxide is especially high in slow-moving petrol light vehicles, petrol SUVs and diesel SUVs.
At normal environmental concentrations, carbon dioxide has no impact on humans. The effect of CO2 emission is a well-debated topic, with its contribution to the greenhouse effect being well documented.
Nitrogen dioxide is an irritant gas, which at high concentrations causes inflammation of the airways.
NOx gases react to form smog and acid rain as well as being central to the formation of fine particles (PM) and ground-level ozone, both of which are associated with adverse health effects.
Methane is a colourless odourless gas emitted from burning gasoline and fossil fuels. Vehicles are a potent polluting force in bulk. The amount of greenhouse and poisonous gases released into the atmosphere endanger the environment and cause severe health consequences in humans.
Residents question whether the resultant air pollution from speed bumps at the insistence of a few activists are warranted, especially when - as in the recent case - the community at large was not consulted prior to the installation thereof. Traffic calming was originally devised and justified to increase pedestrian safety and to reduce noise, which are obvious side effects of traffic, especially in residential areas. Residents living in close proximity of speed bumps, especially in Dana Bay, complained to the Advertiser of increased road noise due to vehicles coming to a shrieking halt, pulling away, and the concomitant noise of vehicles travelling over the bumps.
Fuel consumption
Also relevant to the air quality considerations are the effect of speed bumps on fuel consumption. Traveling at low speeds, or stop/start traveling as required by the multitude of speed bumps in certain roads has a vastly detrimental effect on fuel consumption of all classes of vehicles.
Often in Mossel Bay, it is residents most concerned about the environment who advocate for speed bumps. Evidence - according to European Union standards as South African standards are lacking - indicates that traffic calming measures such as speed bumps are specifically detrimental to air quality.
Albertyn is registered as a Professional Engineer (PrEng) by the Engineering Council of South Africa (ECSA), a Chartered Engineer (CEng) by the Engineering Council in the UK, and is certified as a Qualified Environmental Professional (QEP) under the Institute of Professional Environmental Practice in the USA, a certification that is awarded for multidisciplinary environmental management expertise.
The Qualified Environmental Professional (QEP) certification was initiated in the USA with the aim of improving environmental management in general and is an international programme.
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