UK Traffic Signs Manual - Chapter 7 The Design of Traffic Signs. 2013-
Figure 5-39; Fira Sans substituted for proprietary font used for text in the original
Source file supplied as EPS to uploader from Department for Transport; 

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/203668/traffic-signs-manual-chapter-07.pdf
Department for Transport (United Kingdom)
Department for Regional Development (Northern Ireland)
Scottish Executive
Welsh Assembly Government