In many auto injury related casualty claims, an injured (and sometimes allegedly injured) claimant will utilize a medical transportation company to get around. Even when they are not using a transportation company regularly, we often find the they do so specifically when attending a medical appointment, legal appointment or independent medical evaluation. What many claims examiner and defense attorneys do not consider is that the transportation drives can often get in the way. Many of these drivers only provide transportation for claimants and they know how claims work. This same group is also aware that some of their passengers are placed under surveillance by the carrier and they love this counter surveillance part of the game. 
These drivers will often look for surveillance of the claimant they are transporting and will clue the claimant in on their presence. During some private investigator trade association meetings, the topic of drivers not only looking for surveillance, but of instances where they have tried to actively get a picture of the investigator or get his or her license plate are discussed.
Just as carriers monitor questionable physicians and treatment facilities, it is a great idea to keep track of instances with problem transportation service providers. This information will help your surveillance investigators to remain unnoticed and produce better surveillance results for you.