also been suggested that the luminance variation ratios allowed in the British Standard are too high and that greater uniformity of brightness should be specified.
Regarding (ii) we are aware that much thought and care has been taken in the design of sign lighting lanterns to meet the requirements of the British Standard, but we are not satisfied that the requirements are always being met, even with newly erected equipment. We appreciate that the problem is not an easy one and that the mounting of the lantern in relation to the sign plays an important part in the final result. We suggest that a much improved light distribution would result from the more widespread use of tubular fluorescent lamps in suitably designed trough reflector lanterns, particularly for the larger signs. Functionally, the best position for the lanterns is below the sign so as to avoid shadows being cast on the sign face in sunlight. But we realise that on all-purpose roads there tends to be a risk of malicious interference where the lanterns are mounted below the sign, and we recommend that where this risk exists the lanterns be placed above the sign.
As regards (iii) we cannot stress too strongly the importance of adequate maintenance of lighting equipment and we refer to this in paragraphs 286 and 287.
In view of the general inadequacy of the present sign lighting arrangements, and signs above the maximum size of 6 × 6 ft. quoted in the Standard are likely to be more common in the future, we recommend that the Standard be reviewed without further delay, and that emphasis be given to the points mentioned above.
263. Care needs to be taken in the mounting of sign lighting lanterns to ensure that no distracting stray light is shed in directions behind the sign and that the lanterns do not obstruct any part of the sign face. The former is particularly objectionable on unlighted roads where the stray light may mislead drivers approaching from the opposite direction. Careful adjustment of the brackets supporting the lanterns and the provision, where necessary, of suitable screens should overcome these defects . Shadows cast by the lanterns in strong sunlight can also be troublesome . This needs to be borne in mind in the design and mounting of the lantern if this shadowing is to be kept to a minimum.
264. Roadside signs should be so placed that a driver is able to read their message in sufficient time to take any necessary action safely. The correct distance between the sign and the junction or hazard to which it relates depends on the average speed of traffic on the road and on road conditions . The increased speed of modern vehicles has tended to result in many signs (perticularly advance direction signs) erected some years ago now being too near the junction or hazard to which they relate. When existing signs are replaced by new types it is important that they should be sited at correct distances from the junction and these are indicated in Appendix VII.
265. Lane indication signs (figure 133) on the approaches to signal controlled
junctions should be sufficiently far back to enable all drivers to take the correct
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