See below for explanation
Peter W Jones MInstP
See also
www.schoolminibusaccidents.wordpress.com
SECTION 1 ANEMOMETERS
Peter W Jones MInstP
GCSE. Physics. Single Subject
Anemometers.
It has been suggested that caravans/trailers (including HGV trailers) would be much safer if tow vehicle drivers were aware of the velocity of the wind blowing at them from the side which tends to make the trailer snake or jack knife.
As the faster the trailer goes the more likely it is to snake, it would help if the tow vehicle driver knew the trailer air velocity.
A normal anemometer ( used on sailing cruisers for instance) gives a read out of wind speed and direction ( ie velocity).
The diagram on Page 185 of OCR Gateway “Science for OCR GCSE Biology, Chemistry and Physics B” shows how the writer calculates the resultant of two velocities. A similar thing can be done in reverse. Starting off with V (the wind velocity acting on the trailer), the wind velocity acting on the side of the trailer would then be Vh and Vv would be the trailer air velocity.
The wind velocity acting on the trailer has been “resolved” into two components at right angles to each other to better understand the effect of the wind on the trailer.
If the diagram shown in the text book were drawn to scale the two resolved velocities could be found from the diagram. See also the above diagram.
As shown in the text book these values can be calculated.
If the ordinary anemometers had their software modified they would in effect do this calculation and the revised anemometers would then give a read out of air velocity and side wind velocity.
The company in the UK that manufactures a suitable anemometer has already confirmed that the above proposal could be acted on.
Trains also need this type of anemometer to improve safety on our railway net work, particularly if they are “high speed trains.” At the time of writing anemometers modified as above would be prohibitively expensive for recreational trailer towers, but for railway trains and HGV trailer towing vehicles the cost would be more in line with that of the rolling stock. In addition, when Governments catch up with their knowledge of Physics/aerodynamics they will legislate to make these anemometers compulsary.
If the Met Office improved the availability of their excellent wind forecasts on the internet, by making them available via telephone, there would be far fewer accidents and recreational towers would also benefit in this case.
The above needs a brief mention to GCSE Physics classes. It is the type of item which shows the relevance of Physics to current problems and is likely to generate interest in studying Physics for “A” level.
Advice for HGV Articulated Lorry Drivers.
See above diagram
This topic could also be revisited in either “A” level Maths or Physics classes. From the above diagram it can be seen how the HGV tractor plus trailer is subject to an air speed of 80mph and 56mph of this is contributed by the forward motion of the HGV. HGV’s are currently restricted to 56mph road speed, but year 12/13 students will understand that, as with air craft, the critical speed is the air speed.
Currently accidents arising from this type of problem are not investigated with anything like the rigour applied to aircraft accidents. In my opinion this is one of the reasons why air travel is the safest.
The Select Committee on Transport of the House of Commons have recently produced a very long report containing numerous suggestions for improving road safety, one of which is that the investigation of road accidents needs to be more transparent.
This means ( in my opinion) that results of road accident investigations which reveal important new information should be published on the internet as they are for air accidents.
This is much more likely to happen if the Select Committee on Transport are supplied with extra evidence to support their requests to the DfT. It is the job of the Select Committee to criticise the Government. Year 12 and 13 students in particular (if supported by appropriately qualified physics/mechanical engineering teachers), could provide some of this extra evidence.
In the past such activities would have required enormous effort to write every thing in good handwriting and illustrate same with immaculate diagrams. Today it should be possible to use work done with the aid of a computer as part of normal course work for exams. It would just need to be printed so that teachers and students could sign the documents and send them off by post.
As local councils in the UK control the Police Authorities via nominated councillors who are members of these authorities, the details mentioned above should be sent to these councillors.
Physics extra curricular activities.
Most insurance companies advise that drivers should never admit liability for an accident; lorry drivers can not therefore be expected to divulge details of a jack kifing /snaking hgv trailer accidents.
There are virtually no anemometers at the side of roads or railway tracks in the UK and currently no advice is issued by manufacturers concerning critical air speeds and side wind speeds for road trailers and trains. However, there are always many other witnesses of accidents who will be only too willing to assist in any enquiries which may lead to a better understanding of the science which could produce a reduction in accidents.
When an accident is reported via the media students can ascertain from
the likely wind gusting velocities for the region and add this information to the eye witness accounts. I am sure that local media will assist with such activities carried out by schools/colleges.
The above procedures would need the approval of Governors, Head Teachers, and Parents.
See www.caravanaccidents3.wordpress.com
Scroll down to item on “Air Speed Indicators” for further information
see further items on gcse/gce “A” level in www.schoolminibusaccidents.wordpress.com
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