Construction
A mobile warning device 16.There was disagreement about the central term ‘a mobile warning device’. Mr Keay submitted that it was a term of art, meaning a vehicle mounted sign which is used on a vehicle in motion behind a mobile work site. His point was that the vehicle must be in motion during use of the device and therefore claim 1 excludes a device which is merely mobile in the sense that it can be moved from place to place or in the sense that it can be used while on a stationary vehicle. 17.Mr Keay said that this definition emerges from the Patent specification and was confirmed by expert evidence. He relied in particular on Figure 3 of the Patent and submitted that it would be immediately clear to a skilled person looking at it that this is a vehicle mounted sign which is used on a live carriageway behind a mobile work site. This is Figure 3:
18.The description of Figure 3 in the specification states only that it shows the arrangement of lights of an embodiment of the invention. I do not find any support for Mr Keay’s definition in Figure 3 or elsewhere in the Patent. 19.Dr Meseberg addressed his understanding of the term ‘mobile warning device’ in his report (where he used the abbreviation MWD): “[39] [The skilled person] would know that a MWD is necessarily mobile. It will be mounted on a trailer for a work vehicle itself so that it can serve its warning purpose while actually being driven slowly along a live lane of carriageway …” 20.He was not cross-examined on this statement. Mr Knight was cross-examined on the subject and said that ‘mobile warning device’ was neither a term of art nor even a term which was ever used by those in this field. ‘Advance warning sign’ or ‘chapter 8’ are terms used. (There is a regulatory explanation for ‘chapter 8’ which doesn’t matter.) Mr Knight agreed that in the context of traffic management a mobile sign is one that is used when mounted on a vehicle, but not that the vehicle must be in motion when the sign is used. 21.Even though Dr Meseberg was not challenged on his understanding of the term ‘mobile warning sign’, I cannot rely on that evidence because he is not familiar with practice in the UK and the terms used in this country. He gave no reason for the assertion in his paragraph 39 quoted above. I think it was just that – an assertion without any basis of knowledge about what those in the field in the UK say. I accept Mr Knight’s evidence that the UK-based skilled person would not ever have used the term ‘mobile warning sign’. I also accept that the word ‘mobile’ in this context would be taken to mean that the device is vehicle-mounted when in use, but the vehicle need not necessarily be in motion during use of the device. 22.I also find that the conventional understanding of ‘for’ would apply to a ‘mobile warning device for road traffic’. The device must be suitable for directing road traffic.