Magnetic roof signs and motorway tuition.

10/09/2019

With impending changes in legislation we have had an increasing number of driving instructors asking about the suitability of magnetic roof signs for motorway tuition.

The questions that we get asked are:

‘What is the speed rating for the sign?’, ‘What speed are they guaranteed to stay on at?’ ‘How fast can we go before they come off?’ etc. Applying some common sense we give the following answers:

First of all if you have been teaching to the national standard your client will have had experience of higher speed roads and dual carriageways. The latter of course have the same speed limit as motorways so neither you nor your client should really be worrying that motorway tuition will affect your use of a roof sign.

Of course, NO professional manufacturer can in all honesty give a speed rating for a sign: It would be impossible to assess that without testing to destruction every sign, on every type of car used for tuition, in every possible position on the car roof and in all weather conditions! Furthermore, you can’t ask for a removeable sign and then demand a guarantee it will not come off!

What we can tell you is that the signs we supply at G6S have the strongest magnet assembly available in the UK market. Like all manufacturers we caution that the signs should not be used beyond the maximum speed limit in the UK. That is 70mph and is the same on motorways and dual carriageways. Like all manufacturers we also caution that the signs should not be used in extreme winds. Think about it – if you are driving at 70mph into a headwind gusting up to 60 mph then you are expecting the sign to cope with a net speed of 130mph. Even without the drag of a conventional roof sign, there are very few tuition vehicles out there that we could possibly use to test these signs to destruction – we would never achieve the speed!

The driver is responsible for the vehicle and any load on it so the driver (or instructor teaching a client) is responsible for taking the decision as to whether a roof sign can be safely used for the proposed lesson in the prevailing conditions. Common sense is required and what instructors should do is make sure they have spare L-plates in their vehicle should they feel conditions are too severe to risk using their roof sign.

Air resistance increases with the square of speed so the traditional roof sign becomes a real drag as speed increases and the forces on it are substantial. Consider using one of our aero signs which are designed for reduced drag! Whichever sign you use, keep it in tiptop condition – check regularly that the base is securely attached to the hood and that the magnet assemblies are secure.