T (Thymus Derived) Lymphocyte Count. Definition. T cells are a type of white blood cells (lymphocytes). They make up part of the immune system. T cells help the body fight diseases or harmful substances. A test can be done to measure the number of T cells in your blood. Thymus derived lymphocyte count; T-lymphocyte count.
The road test generally takes 15 to 20 minutes. 1  If you fail the road test you must wait a minimum of two weeks (14 days) before taking the road test again and must pay another $40 testing fee. 2  Test results are valid for 2 years. If you fail the road test you must wait a minimum of two weeks (14 days) before taking the road test again and must pay another $40 testing fee. 2  Test results are valid for 2 years.
The depending on your vehicle, the test should take between 15 to 30 minutes to be complete. The Test Center is required to begin the test within twenty (20) minutes of your arrival and end within ten (10) minutes of the initiation of the test.