http://www.engineeringnews.co.za
  SEARCH
Login
R/€ = 13.93Change: 0.00
R/$ = 12.67Change: -0.01
Au 1095.49 $/ozChange: 0.31
Pt 984.00 $/ozChange: 2.00
 
 
Note: Search is limited to the most recent 250 articles. Set date range to access earlier articles.
Where? With... When?








Start
 
End
 
 
And must exclude these words...
Close Main Search
Close Main Login
My Profile News Alerts Newsletters Logout Close Main Profile
 
Agriculture   Automotive   Chemicals   Competition Policy   Construction   Defence   Economy   Electricity   Energy   Environment   ICT   Metals   Mining   Science and Technology   Services   Trade   Transport & Logistics   Water  
What's On Press Office Tenders Suppliers Directory Research Jobs Announcements Letters Contact Us
 
 
 
RSS Feed
Article   Comments   Other News   Research   Magazine  
 
 
Aug 09, 2012

Variable speed limits not always effective, study shows

Back
Engineering|Road|Roads|Safety|transport|Trucks|Stellenbosch University|Western Cape|Christo Bester|Electronic Stability Control
Engineering|Road|Roads|Safety|transport|Trucks||||
engineering|road|roads|safety|transport|trucks|stellenbosch-university-facility|western-cape|christo-bester|electronic-stability-control
© Reuse this



There is no reliable evidence of the safety benefits of buses and heavy trucks adhering to lower speed limits than passenger cars, suggests new research by Stellenbosch University (SU).

In 1999, following a fatal bus collision involving British tourists, the then Minister of Transport reduced the maximum speed limit for public transport vehicles (buses and minibus taxis) to 100 km/h. Heavy vehicles were already limited to 80 km/h.

SU civil engineering professor Christo Bester says there are a number of safety-related reasons why different speed limits could be applied to different types of vehicle.

For example, because of the differences in mass, different vehicles have different stopping distances. And, related to the inter- action between the tyres and the road surface is the ability of a vehicle to negotiate a horizontal curve. Excessive speeds can lead to a vehicle slipping, or overturning on a sharp curve.

Different vehicles also have different safety features, such as crumple zones, passenger restraints and electronic stability control.

However, despite these benefits, the application of variable speed limits is not without problems, with the most important of these being the ability to effectively enforce different limits on the same road, says Bester.

Variable speed limits are only regarded as effective when 85% of drivers keep to the designated limit. However, from studies carried out in the Eastern and Western Cape, 60% of minibus taxis did not comply with the speed limit, with the same being true for 64% of heavy goods vehicles.

Bester says automatic speed cameras cannot differentiate between vehicle types, which is why only the highest limit can be enforced.

Speed cameras that are manually operated or sophisticated apparatus with access to the South African vehicle database (such as the speed-over-distance camera) is necessary.

“It is clear, however,” emphasises Bester, “that minibus taxis and heavy vehicles do not adhere to their maximum speed limits. It is clear that these [variable speed] limits should be reconsidered or at least enforced on a larger scale than is currently the case. If the limits are not enforced, there is clearly no justification for having them.”

Bester also questions why legislation regarding the 80 km/h speed limit refers to heavy goods vehicles only.

“Why allow a higher speed limit for buses than for other heavy vehicles? Or vice versa – why force drivers of heavy goods vehicles to travel slower than heavy passenger vehicles?

“Some reason that the value of time is higher for passengers than it is for freight and, therefore, buses should be allowed higher speeds, but this is an economic decision and not one that relates to safety – the main reason given for speed limits. Economic decisions regarding vehicle travel should be taken by operators and not legislators.”

Another problem is that international research has shown that increased differ- ences in speed also result in higher crash rates, as faster and slower drivers have to be accommodated in the same road space. Particularly in two-lane, two-way roads, differentiated speed limits can result in reckless driving behaviour.

Bester says research has shown that the chance of being involved in a road acci- dent is lowest when the vehicle is travelling around the average speed of the surrounding traffic.

In the end, argues Bester, there is no reliable evidence of the safety benefits of variable speed limits. However, there is a concern that by increasing the speed variance, differential speed limits may increase overall accident rates.

“This is a solid argument against a differentiated speed limit between heavy vehicles and other road vehicles, and in favour of a standard speed limit for all vehicles.”

Bester then also suggests the introduction of a lower maximum speed limit for all vehicles, as proposed by the former Minister of Transport, as well as the further reduction of maximum speed limits on single lane roads, in line with international practice.

Edited by: Martin Zhuwakinyu
Creamer Media Senior Deputy Editor
© Reuse this Comment Guidelines (150 word limit)
 
 
 
 
 
 
 
 
Other Automotive News
Daimler truck test engineer Dirk Stranz pushes one button and then retracts his hands from the steering wheel of the Mercedes-Benz Future Truck 2025. “And now the truck is driving itself.” It is unsettling to see the steering wheel move unaided as the truck gently...
Hino has embarked on a strategy to become the number one truck brand in South Africa by 2020, says Hino South Africa (SA) VP Ernie Trautmann. Hino is currently placed third in the market, trailing Mercedes-Benz and Isuzu Trucks.
Article contains comments
More
 
 
Latest News
Embattled South African steel producer ArcelorMittal South Africa (AMSA) has offered insight into the “fair pricing model” it has tabled before government in return for tariff protection and a government stipulation that locally manufactured steel be designated for...
Telecommunications group Telkom on Friday said it had posted a 1.7% uptick in net revenue for the three months to June 30, on the back of a strong performance by mobile on data revenue and higher fixed-line subscription revenue. Mobile net revenue for the first three...
Dangote Cement revised its 2015 spending plans to $1-billion from the $700-million estimated nine months ago after it commissioned two new African plants this June, Nigeria's biggest listed company said on Friday. The company, majority owned by billionaire Aliko...
More
 
 
Recent Research Reports
Real Economy Year Book 2015 (PDF Report)
There are very few beacons of hope on South Africa’s economic horizon. Economic growth is weak, unemployment is rising, electricity supply is insufficient to meet demand and/or spur growth, with poor prospects for many of the commodities mined and exported. However,...
Real Economy Insight: Automotive 2015 (PDF Report)
Creamer Media’s Real Economy Year Book comprises separate reports under the banner Real Economy Insight and investigates key developments in the automotive, construction, electricity, road and rail, steel, water, gold, iron-ore and platinum sectors.
Real Economy Insight: Water 2015 (PDF Report)
Creamer Media’s Real Economy Year Book has been divided into individual reports under the banner Real Economy Insight and investigates key developments in the automotive, construction, electricity, road and rail, steel, water, coal, gold, iron-ore and platinum sectors.
Real Economy Insight: Construction 2015 (PDF Report)
Creamer Media’s Real Economy Year Book has been divided into individual reports under the banner Real Economy Insight and investigates key developments in the automotive, construction, electricity, road and rail, steel, water, coal, gold, iron-ore and platinum sectors.
Real Economy Insight: Electricity 2015 (PDF Report)
Creamer Media’s Real Economy Year Book has been divided into individual reports under the banner Real Economy Insight and investigates key developments in the automotive, construction, electricity, road and rail, steel, water, coal, gold, iron-ore and platinum sectors.
Real Economy Insight: Road and Rail 2015 (PDF Report)
Creamer Media’s Real Economy Year Book has been divided into individual reports under the banner Real Economy Insight and investigates key developments in the automotive, construction, electricity, road and rail, steel, water, coal, gold, iron-ore and platinum sectors.
 
 
 
 
 
This Week's Magazine
Daimler truck test engineer Dirk Stranz pushes one button, and then retracts his hands from the steering wheel of the Mercedes-Benz Future Truck 2025. “And now the truck is driving itself.”
The statutory body responsible for skills development and support in the banking sector, BANKSETA, was investing R68-million in the capacity building project of the University of Venda (UniVen), announced Bankseta company secretary Caroline King at a media event in...
LIONEL MOYAL Cloud services providers must compete against other cloud services providers for business by providing up-to-date systems and services
Legacy information technology (IT) systems are becoming increasingly obsolete because of the maturity, efficiencies and cost effectiveness of cloud-based IT services, says information and communication technology major T-Systems subsidiary Intervate head Lionel...
ARMANDÉ KRUGER Balancing the collection and processing of data must be aligned to strategy
Many complementary services enable companies to derive broad value from data inside and outside them. The complexity of data management means that companies’ strategies determine the various data systems and functions they will use, says PBT Group regional sales...
The South African Civil Aviation Authority (SACAA) has announced that it had awarded the country’s first remotely piloted aircraft systems (RPAS) pilot’s licence. It was issued on Friday, July 10, to SACAA employee and qualified commercial pilot Nicole Swart,...
 
 
 
 
 
 
 
 
 
Alert Close
Embed Code Close
content
Research Reports Close
Research Reports are a product of the
Research Channel Africa. Reports can be bought individually or you can gain full access to all reports as part of a Research Channel Africa subscription.
Find Out More Buy Report
 
 
Close
Engineering News
Completely Re-Engineered
Experience it now. Click here
*website to launch in a few weeks
Subscribe Now for $96 Close
Subscribe Now for $96