This report describes a number of tests of the readability of variable message traffic signs that were carried out in a period from the spring of 2008 until the autumn of 2009. An even earlier test is not mentioned. A variable message traffic sign is called VMS in the following. The tests are described approximately in the sequence they were carried out. To some degree the sequence describes a "learning by doing" process in which later tests were based on earlier tests. All the tests involve presentation of a number of prearranged messages on a VMS, representing variation of some parameters supposedly related to the readability of the messages, to a group of test persons. In the early tests, the criterion for the readability was the reading distance of each of the messages for each of the test persons. In the later tests the criterion was rating of the readability at predetermined distances.