Archive for October, 2008

October 28, 2008

 

 

 PARAGRAPH 32

 

SNAKING CARAVANS AND TRAILERS (INCLUDING HGV TRAILERS

 

Peter W Jones  MInstP

Retired Head of Science in a Birmingham Comprehensive School ( 20 years)

Currently, “Consultant for Towed Vehicle Accidents” (5 years)

Apart from 19 months national service ( ie conscripton) in the RAF my entire career (almost) has been as a full time teacher. I was a comprehensive school Head of Science for 20 years, but I also spent 7 years as a full time lecturer in a Birmingham Technical College (Further Education Sector).

This blog, and the two linked to it, have therefore turned out to be an untidy set of notes and resource material for teachers/lecturers. After 41 years as a teacher I have difficulty switching to the right mode when writing.

I started advising on oscillating trailer accidents in 2003 (after I had been retired  for 10 years) when I became an Affiliate of the Institute of Traffic Accident Investigators. I had no desire to become an “Accident Investigator” but learned a great deal by reading their journals,  attending some of their meetings/courses, and particularly by exchanging scientfic information concerning road traffic accidents via a private internet site which was used by many ITAI members.

I was also an Associate Member of the Society of Expert Witnesses for a further 12 months and derived great benefit from their extensive written legal advice for “expert witnesses,” and their “mentoring support.”

I am not allowing a direct connection with myself via the web as I was originally  (in 2007) almost put out of action by “comments” to my blog on 20six.co.uk which were mainly pornographic. I am currently relying on private contacts and exploring other means of advertising at low cost as I am working on a charitable basis in support of road safety. My blog details have been circulated by a group of interested solicitors and I am always available to give advice by telephone, particularly as most questions can be answered by reference to items I have written and published on the net. If the solicitors have a problem with passing on technical information I am prepared also to discuss the matter by telephone with the Accident Investigators.

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Addendum Oct 2009

Technorati/Wordpress, as you will see on the internet, have from the beginning of October 2009, started to give more prominence to my blogs. They are keen to promote blogs of a Scientific/Technological nature.

A feature of the new system is that comments are allowed, but these will be carefully screened to eliminate spam.

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VOCATIONAL COURSES FOR TRAFFIC ACCIDENT INVESTIGATORS, ROAD SAFETY OFFICIALS, AND HGV drivers.

Leaving out my “political” offerings most of the items I have written about should  be considered for inclusion in the above courses.

SCHOOL LEVEL WORK

GCSE Physics;  The effect of the centre of Mass of a vehicle on its stability is one item I have taught at this level.

I expect that there is at least one of the many courses for GCSE which contain some Physics for which my lever test for friction based caravan/trailer stabilisers would be a good “practical application.”

I have used Newton’s First Law of Motion to explain why it is very foolish of us to allow unbraked trailers (up to 0.75 tonnes) to be used on our motor ways.

Vectors using scale diagrams

 

GCE “A” level Maths (Theoretical Mechanics/Applied Maths) and GCE “A” level Physics

I have made use of Vectors in writing about the effect of the wind on high aspect vehicles and although I later had the better idea above I originally used some equations of motion to show very approximately that friction based stabilisers could not make any significant contribution to bringing a snaking trailer under control.

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October 23, 2008

EDIT 19/04/12
THE OPINIONS EXPRESSED IN THIS BLOG ARE MINE AND ARE NOT NECESSARILY THE SAME AS THOSE OF THE INSTITUTE OF PHYSICS

For more recent material concerning the serious deficiency I have discovered in the C&G Police Syllabus for trainee Police Accident Invesigators see my blog:-
http://www.westmidlandspoliceauthority.wordpress.com

GCSE MATHS/STATISTICS (HGV accidents)

Peter Jones MInstP
Edit Feb 2011

These statistics are to be read in conjunction with those in Para 44 below and further results for LGV’s in my WMPA blog.

http://www.hgvaccidentstatistics.wordpress.com

The errors in the compilation of the HGV statistics should be easily understood by GCSE students and it would therefore be appropriate if teachers sought the permission of Head Teachers and Governors to send a representative sample of students’ comments to the West Midlands Police Authority. This type of activity provides a valuable link between school and the real world.

It is to be hoped that the WMPA ( and other police authorities) should in future ask the police to display their accident statistics on line so that students and the public can monitor the situation.

The HGV Industry has been concerned for many years over the safety of Articulated Lorries. This is revealed by the fact that they have had Articulated Lorries researched at Bath University, but not rigid HGV’s towing a trailer ( as far as I am aware).
(Put “The Dynamics of Towed Vehicles Killer CJ 2003” in to Google to see a M Eng project report. Page 9 end of para 2 justifies my above comment, and elsewhere in the same document is a description of the testing of the ALKO caravan/trailer stabiliser which I have previously written about in my blogs [para 31a and 36 below])

It can now be seen why we need to have three categories in the accident statistics for HGV’s:- (1) HGV’s (2) Rigid HGV’s towing a trailer and (3) Articulated Lorries.

HGV ACCIDENT STATISTICS

I must emphasise that these statistics contain the last public information (to the best of my knowledge) that the West Midlands Police issued on HGV accidents in their area.
These show that there were 2153 HGV accidents in the West Midlands Police area in the 5 years to 1994.
This gives an average of 8 HGV accidents per week ( national average for all Police forces = 5 per week in the same period) in the West Midlands and according to current DfT statistics more HGV accidents happen on motorways than class “A” roads.
No information was given as to whether the HGV’s were towing a trailer or whether the HGV was a “rigid” or an Articulated Lorry.

Academic entry requirements for police constables to transfer to accident investigation have never been published (as far as I can establish). It is my understanding that there are no entry requirements. Further more I have seen no evidence to show that there is a professional engineer (at least C Eng level) to advise the accident investigators.

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Due to problems with the blog software I have pasted these statistics in to a new blog

http://www.hgvaccidentstatistics.wordpress.com

Peter W Jones  MInstP

I REGRET THAT THE BLOG SOFTWARE HAS PLACED THE NEW

                                              INTRODUCTION

          A  FEW PARAGRAPHS BELOW  AFTER PARA 31

 See also
www.improvingroadsafety.wordpress.com      the most rcent blog

plus

www.caravanaccidents2.wordpress.com    

www.caravanaccidents.wordpress.com 

www.20six.co.uk/roadtrafficaccidents

Advice for Physics and Maths teachers and the Younger Generation  (GCSE and GCE “A” level)

www.schoolminibusaccidents.wordpress.com     and

www.schoolminibustrailers.wordpress.com

Index

31  Highways Agency Fit to Tow Video

31a   Bath University Caravan Research

32  Summary of ideas behind Blogs by Peter W Jones

33  Air Speed Indicators

34  Lobbying Parliament

35  Letter to Dr Tony Wright MP

36  Bath University on Stabilisers (cont)

37  Stabilisers; further details

38  Letter to Mrs Dunwoody  MP

39  Caravan Stabilisers explained for

        non caravanners

40  IVRA Conversion Kit for Over run Brakes

41   History of New ALKO electronic conversion kit

42  USA Electric Brakes

43  Stabiliser test by Peter W Jones

44   HGV Trailers ( includes accident statistics)

45   Wind induced Road Accident

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Paragraph 31

THE HIGHWAYS AGENCY FIT TO TOW VIDEO (see their web site)

Peter W Jones  MInstP

The Highways Agency “Fit to Tow” video, presented by Carol Smillie, has been available for viewing on the inter net for some time.

I welcome the fact that the HA have now modified the DfT presentation of Caravan and Trailer accident statistics. (see my 2006 paper published by the HoC Select Committee on Transport by putting “Caravan and HGV trailer accidents” in to the search engine of www.parliament.uk )  

It is well known that the Caravan Club/Caravan Industry policy is that incorrect “load distribution” is  the main cause of towing accidents. I do not think it appropriate that this video, with a contribution from ACPO, should promote this viewpoint.  Bath University Research has proved that friction based stabilisers do not improve safety and  hgv’s can destabilise caravans. The HA in other published items is also now warning caravanners of the effects of strong cross winds and these factors will cause problems even when your caravan is correctly loaded and you are towing with a suitable tow car.

With regard to the towing of trailers with no brakes the HA is assuming that the tow car brakes will be adequate to stop a 0.75 tonne trailer. However, this will not be the case if sharp braking is used at normal motor way speeds. When the tow car brakes sharply, If the trailer is directly in line with the tow car the trailer will rise and smash into the back of the car or pass right over the top if the HA suggested safety chain is unable to prevent this taking place. When the trailer and tow car are not in line the trailer will jack knife, and if the latter is much greater in weight than 50% of the tow car weight ( the legal limit ?) there is a high probability of the tow car being destabilised.

All this follows directly from Newton’s First Law of Motion.

The Institute of Traffic Accident Investigators reported in 2002 in their Journal that they had tested braking a tow car with an unbraked trailer at 40 mph and found that the trailer jack knifed every time.

Also see para 3a of my blog www.caravanaccidents2.wordpress.com  for an account of a related accident when the “over run” brakes failed to function.

 
 
 
 
 

 

 
 
 
 THERE IS A GAP HERE CAUSED BY THE REMOVAL OF THE DFT CARAVAN ACCIDENT STATISTICS AS PRESENTED BY CAROL SMILIE.
 

 

WORDPRESS DOES NOT SEEM TO BE ABLE TO REPEL ALL HACKERS, but the section copied from the Highways
Agency is also in
  
  
Scroll down to line in bold type starting
“THE ANNUAL AVERAGE NUMBER OF  MILES
COVERED………”
 

12/12/09

see www.20six.co.uk/roadtrafficaccidents  

I WAS WARNED BY THE AUTOMATIC SYSTEM SOME TIME AGO THAT AN ATTEMPT HAD BEEN MADE TO BREAK IN