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Studies were conducted with a driving simulator to determine the effects of displaying changeable-message-sign messages with dynamic features consisting of (a) flashing all lines simultaneously in a one-phase, three-line message and (b) flashing one line (top line) of a one-phase, three-line message. In the first dynamic feature, all three lines were flashed. Only the top line was flashed for the second dynamic feature. Messages with these two dynamic features were compared with comparable static messages. No differences in average reading time were found between the messages in which all three lines flashed and static messages. However, the results suggest that flashing an entire one-phase message may have adverse effects on message understanding for drivers who are unfamiliar with this dynamic mode of display. A significant percentage of the subjects preferred the static display. The average reading time for the flashing line (top line) messages was significantly longer than for the static messages. The results also suggest that unfamiliar drivers will be adversely affected by this particular display feature, relative to comprehension of the entire message. The subjects liked the flashing line and static messages equally well. No differences were found by age, education, and gender among the three dynamic message modes and their alternatives. In addition, no differences were noticed in driving performance.

The accuracy and precision of five common portable speed measurement systems were evaluated in a controlled field evaluation. The following systems were evaluated: traffic classifier with pneumatic tubes, traffic classifier with piezoelectric sensors, tape switches, radar, and lidar (i.e., police laser). A test vehicle with a calibrated Nitestar distancemeasuring instrument (DMI) made 100 passes through the test site at two speed levels (50 passes at 55 mph, 50 passes at 35 mph), and speed was recorded by each device for each pass. DMI speed was deemed the "true" speed for each pass, and deviations from the DMI speed for a given device were considered errors. Paired t-tests were performed on the speed data measured by each device versus the DMI. The following conclusions were drawn: ( a) All devices performed equally well for the 35-mph trials. ( b) Lidar and radar were the most accurate and precise devices for the 55-mph trials. ( c) For all devices, any errors that occurred for a single speed measurement were relatively small (less than ±1.5 mph). ( d) With the exception of radar, all devices were slightly less accurate and less precise at higher speeds. ( e) There was little difference in performance between on-pavement devices (i.e., tubes, piezoelectric sensors, and tape switches). ( f) Inaccuracies observed in on-pavement equipment likely were caused by slight measurement errors during placement of the sensors or movement of the sensors resulting from repeated tire hits. Because all devices were relatively accurate, the researchers recommended that portable speed measurement equipment be selected to suit the characteristics of a given data collection situation.