See also 


Paragraph 33 


Air Speed Indicators


Peter W Jones MInstP


.In drawing attention to the need for the above I am suggesting a change that has not, as far as I know, been proposed elsewhere.The Caravan Industry and the Caravan Clubs have regrettably resisted the use of safer technology for some years and have left the EU/UK very much in a technological backwater, whilst the air craft industry (Air Bus) are now amongst the world leaders.As Standen’s 1999 Bath University Phd thesis (Towed Vehicle Aerodynamics) still only resides in the British Library on microfiche, few people are aware of the fact that he proved in wind tunnel tests (with scale models) that an HGV could destabilise a car/caravan combination and aerofoils improved the stability of a caravan.In 2003 when I was using the Road Traffic Accident Investigators private Yahoo e mail system and circulated the above and other details of the Bath University research I discovered that the aerodynamic research mentioned above was quite unique far beyond the EU, and the fact that it must also at least apply to some HGV trailers ( the need for aerofoils) was also not known.

However, it may well be that research has been done that has not been published.
Even with aerofoils and electronic brakes there will still be an upper speed limit for all vehicles, particularly trailers, which must be decided on the basis of the Laws of Physics and then enshrined in Government regulations as is already done in a similar manner for the air craft industry.
I do not think it will ever be necessary to take as many precautions for solo vehicles as if you cannot sense yourself the effect of the wind on the vehicle you are driving, you should not be in charge on the road. When towing a trailer there is another vehicle to be considered with very different characteristics, and an electronic system is needed to give information about the forces on the trailer as well as an air speed indicator.
Designing a suitable air speed indicator for use by road and rail vehicles will be comparatively easy once the need for same has been accepted. All that is required is a “weather vane” (to sense direction) and rotating parts ( to sense speed)   


The direction that the “weather vane” would point is determined by the wind produced by the forward motion of the vehicle and the wind ( if any) resulting from natural weather fluctuations. The software would then convert this into a “Head wind” component (in mph) and a “side wind” component. The two speeds would be displayed for the driver to read.
The maximum safe air speed ( road speed plus head wind component) must be established for each vehicle, but this as with aircraft will vary depending on the load being carried.
Similarly the side wind component will vary, but for the driver (as with the pilot) this only has to be looked up once in a set of tables for each journey. There would have to be anemometers in exposed places at the side of major roads to send out details of side wind speeds by radio ( information is currently transmitted by the RAC that determines “congestion points” by measuring traffic speed at many points on all major roads in the UK).
For minor roads drivers would still have to depend on the wind speed forecasts given by the met office, as we shall still have to do for some time in all cases.
Even if there are no fatalities or serious injuries every time an HGV trailer over turns or otherwise gets out of control we have a major problem as it takes some hours to get a crane to the site which is capable of lifting up the wreckage. A caravan is easily pushed out of the way by a Police Land Rover.
When considering the costs of my proposals the lost productive hours of the many thousands of people caught up in resulting traffic jams should be taken into account.
Currently I do not think the DfT have any records concerning HGV or caravan accidents resulting from the effects of the wind, as this in the past has not been properly recognised as a serious problem.  



Addendum 5-11-08.

It seems that I was seeking information concerning currently available anemometers for road and rail vehicles in the wrong place. I should have used Google !

There are suitable appliances on the market that will only need a comparatively minor modification ( to the software only in some cases) to meet the requirements of locomotives and road trailers.

It is most probable that suitable hardware already exists and the only remaining task is to programme same so that the “air speed” and “side wind component” can be displayed.

I have also recently realised that I have failed to draw attention to another aspect of this matter. Formula 1 racing cars and HGV’s with trailers frequently travel at about 100mph air speed, but only the former have the benefit of aerofoils to help keep them in good contact with the road and more able to resist any side forces from the wind. Racing cars are viewed by thousands of spectators and officials are prompt in their control of the situation when extreme weather conditions apply. On the motorways little can currently be done by traffic police in the same situation as critical air speeds and side wind components need to be known for each type of vehicle, as is the case for air craft.

However as I feel certain that the anemometers/air speed indicators that I have outlined above could be produced at a reasonable price and even if they were only half as popular as GPS navigation ( and I feel certain they would cost much less), a considerable contribution could be made towards reducing accidents because drivers would use their own judgement. Governments would then eventually legislate to ensure that ( as with the air craft industry) the critical speeds for each type of vehicle were stated in the manufacturers’ manuals for drivers.


ADDENDUM  22-11-08

I have now written to several manufacturers of anemometers and had one positive reply.    of Portishead, Bristol, UK  sell a suitable anemometer which only needs extra software to be written to convert to my above mentioned specifications.

edit 30-09-09

I received a quote from of around 1500 pounds sterling (UK) for the above during the Summer.

This type of cost will be considered reasonable when more people become aware of the reduction in accidents that would result. However, Governments would have to legislate before the HGV industry would install these devices.

For recreational trailer towers like myself  the cost would be unacceptable at present and I shall continue pestering our Met Office to make more widely available their internet wind speed forecasts. I can always use the internet beore I leave home, but this Summer found myself having to restrict my speed considerably on one journey because I failed to get to an internet cafe before setting out. In another instance I made a detour to avoid the M5 bridge over the river Avon when it may not have been necessary. However, I have lived to start my 34th year of receational towing if the cancer clinic eventually discharge me tomorrow after 5 years of “monitoring.”



Tags: , , , , , , ,

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: