In this study the following photometric aspects of the Dutch technical specifications for traffic signalling (TSV) and dynamic route information panels (TSD) were compared with the European (draft) standard for variable message signs (CEN (European Committee for Standardization)): (1) symbol luminance; (2) contrast; (3) colour; (4) uniformity; and (5) angularity. Possible suggestions for improving the TSV, TSD and CEN requirements are also given. The differences in measurement methods and test conditions between these three standards are briefly described.he photometric aspects of the Dutch technical specifications for traffic signalling (TSV) and dynamic route information panels (TSD) were compared with the European (draft) standard for variable message signs (CEN). The results have led to the following conclusions and recommendations. The requirements for the symbol luminance of traffic signalling of the TSV and the TSD comply reasonably well with the CEN. However, the TSV requirements for tunnel signalling and special signs are less compliant. It is recommended to revise the luminous intensity requirements of the TSV conform the symbol luminance limits of the CEN. In addition, switching regimes are recommended for the TSV and TSD. The minimum symbol luminance of the TSD, at maximum illuminance, should be lowered to 6200 cd/m². The illuminance/angle combinations, as used by the CEN and TSD for the measurement of contrast are realistic. The angle of 0°, prescribed by the TSV, is not realistic and could better be changed in 5°. It is recommended to conform the CEN requirements for colour to the international requirements and to skip the colour yellow. It is also recommended to use the same colours for the TSV as those prescribed for class Dl of the CEN. Also, and the colour area for text information of the TSD should be enlarged according to the white/yellow area of the class D2 of CEN. The requirements for uniformity show large differences, within as well as between the various specifications. The TSD is the most strict and the CEN is the least strict. The two TSV requirements are not matched, which implies that complying to the most strict one obviates the need for complying with the other one. Since the TSV does not specify how the two groups of 9 light points should be sampled, there is a risk that the test results can be manipulated by selective sampling. It is possible to harmonize the uniformity specifications on basis of the standard deviation of the logarithm of the luminous intensity of the light points. Although, the TSV, TSD, and CEN requirements for the angularity are formulated differently, there is already a reasonable degree of concordance of the TSV and TSD with level A and B of the CEN, respectively. For a still better fit the requirements of the TSV and TSD should be adjusted in such a way that the light bundle is wider and flatter. The "small model" of a DRIP prescribed by the TSD does not comply with the CEN requirements for test modules. To simplify the laboratory measurements it is recommended to adapt the dimensions of the small models to the CEN requirements. Further research is recommended, as to arrive at less arbitrary requirements for the uniformity and to gain an insight into the legibility of symbols and letter types used for traffic signalling and DRIP's. (A)
Samenvatting