Lichtdoorlating van stuurhuisruiten
report
Purpose : According to international legislation pilothouse windows of inland vessels should have a minimum light transmission of 75%. The shipping sector is wondering whether this requirement can be reduced since a large portion of the fleet is equipped with green tinted windows panes with a lower light transmission. In this study, we answer the question whether the minimum allowable light transmission of pilothouse windows of inland vessels can be reduced from 75% to lower values of green and bronze tinted windows. Furthermore, a protocol is proposed for the measurement of light transmittance of pilothouse windows in practice.
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Methods : In order gain insight of the visual task of the skipper and to perform photometric measurements we visited eleven inland vessels. We determined a set of light technical parameters such as, window pane type (color, number of layers), light transmission and tilt angle of the window pane, ceiling reflection. Using a visual model the detection distances were calculated for a navigation light at night and an unlit buoy during the daytime, for various light transmissions of the pilothouse window. This was based on the parameters measured on the vessels, standard lighting conditions and the prescribed intensities of signal lights. A proposal for the measurement protocol is made on the basis of market research, modeling and analysis.
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Results : The measurements on the vessels showed that white, green and bronze window panes have an average light transmission of 82%, 64% and 47%. Thus, the green and bronze tinted panes do not meet the current requirement of 75%. The average reflectance of the pilothouse ceiling was 0.555.
The model calculations show that the visibility of objects at daytime hardly is affected by pane transmission provide that the transmission is more than 20%. Compared with a normal window pane (75%) the detection distance for bronze and green tinted windows reduces with 0.7% and 0.2%. At night, the detection distance decreases with decreasing transmission and is also affected by the reflection of the ceiling and the internal lighting of the pilothouse. Compared with a normal window pane the detection distance for bronze and green-tinted windows reduces with 17% and 6%. The negative influence of green tinted windows on the detection distance at night can be compensated by modifications of the interior of pilothouse.
This compensation is not possible for bronze tinted window panes.
For measuring light transmission in the pilothouse window panes in practice, the hand-held measuring devices for car windows can be used provided that the instrument is calibrated for the larger thickness of the pilothouse windows and is equipped with a good shielding for stray light. In addition, a correction for the inclined windows should be applied.
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Conclusion : At daytime tinted pilothouse window panes have a negligible adverse influence the visual perception of objects outside. At nighttime, this influence is larger but for green tinted windows it can compensated by modifying the pilothouse interior. Measurement of light transmission of pilothouse windows in practice with existing measuring devices is only possible if these devices are modified and calibrated for this purpose.
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Methods : In order gain insight of the visual task of the skipper and to perform photometric measurements we visited eleven inland vessels. We determined a set of light technical parameters such as, window pane type (color, number of layers), light transmission and tilt angle of the window pane, ceiling reflection. Using a visual model the detection distances were calculated for a navigation light at night and an unlit buoy during the daytime, for various light transmissions of the pilothouse window. This was based on the parameters measured on the vessels, standard lighting conditions and the prescribed intensities of signal lights. A proposal for the measurement protocol is made on the basis of market research, modeling and analysis.
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Results : The measurements on the vessels showed that white, green and bronze window panes have an average light transmission of 82%, 64% and 47%. Thus, the green and bronze tinted panes do not meet the current requirement of 75%. The average reflectance of the pilothouse ceiling was 0.555.
The model calculations show that the visibility of objects at daytime hardly is affected by pane transmission provide that the transmission is more than 20%. Compared with a normal window pane (75%) the detection distance for bronze and green tinted windows reduces with 0.7% and 0.2%. At night, the detection distance decreases with decreasing transmission and is also affected by the reflection of the ceiling and the internal lighting of the pilothouse. Compared with a normal window pane the detection distance for bronze and green-tinted windows reduces with 17% and 6%. The negative influence of green tinted windows on the detection distance at night can be compensated by modifications of the interior of pilothouse.
This compensation is not possible for bronze tinted window panes.
For measuring light transmission in the pilothouse window panes in practice, the hand-held measuring devices for car windows can be used provided that the instrument is calibrated for the larger thickness of the pilothouse windows and is equipped with a good shielding for stray light. In addition, a correction for the inclined windows should be applied.
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Conclusion : At daytime tinted pilothouse window panes have a negligible adverse influence the visual perception of objects outside. At nighttime, this influence is larger but for green tinted windows it can compensated by modifying the pilothouse interior. Measurement of light transmission of pilothouse windows in practice with existing measuring devices is only possible if these devices are modified and calibrated for this purpose.
TNO Identifier
506783
Publisher
TNO
Collation
30 p. (incl. bijlage)
Place of publication
Soesterberg