VMS Application 

Generally speaking, VMS is used to communicate in real-time with motorists.  VMS messages must address current conditions on the roadway by being dynamic, accurate, timely and understandable. When there are multiple requests to post VMS messages simultaneously, messages will be prioritized in the following order of importance: 
1. Incident Management/Public Safety 
2. Congestion Management/Motorist Guidance 
3. Construction/Maintenance Activity  
4. Special Events 
5. Environmental  
6. Law Enforcement Message 
7. Public Service Campaign

VMS Small Knowledge:
When using text, care should be taken that the text can be read at a sufficient distance. One rule of thumb is that the minimum reading distance (in metres) is about 5 to 6 times the letter height (in cm). For example: a 36-cm high letter can be read at a distance of about 200 m from the sign. 
When planning to install new VMS, authorities should know that the European VMS standard (EN 12966) is obligatory for all fixed VMS signs used in traffic applications. This is not yet the case for temporary or mobile VMS because the Construction Products Directive (CPD) is only valid for products that are in permanent use. An informative appendix of the European VMS standard (EN 12966) provides guidance in choosing the correct combination of the various items mentioned above.