Police are warning truck drivers about rising levels of lorry crime in the West Midlands.
Valuable loads from lorries are being stolen
Figures suggest 19 lorries have been "hijacked" across the UK in the past three months and 13 of these incidents have been in the West Midlands.
Some of the lorry thefts have involved violence against drivers.
Police are now putting lorries in the worst-hit lay-bys which display signs warning drivers that parking up could leave them in danger of being robbed.
The signs have translations in numerous languages to warn foreign drivers working in the UK.
The information about which lay-bys have been worst-hit across the country is being collected and analysed at a Coventry-based police intelligence service.
Police say one method used to hijack lorries is when a person in an official looking high-visibility jacket persuades the driver to leave the vehicle, and then an unseen accomplice drives off with the lorry and its goods.