Artificial illumination plays an important role in a movement safety issue in tunnels. The probability of road accident during the day is high at the expense of a difference in levels of brightness of a daylight and rather dark space of a tunnel. Such readaptation of sight demands the big visual pressure. The return process which is taking place on departure from a tunnel, is not less important, no less than the moment of entrance to the shined tunnel at night. Thus, illumination of these constructions should consider adaptive abilities of a human eye.
Outside entrance to a tunnel looks as a black hole. To rectify situation it is possible by means of the intensive external illumination smoothly decreasing in a transitive zone of entrance. For other tunnel low light exposure is enough. Nevertheless it should be a little above, than from usual street illumination, for decrease in pressing action of underground space. It is recommended before departure from a tunnel to raise light exposure for more safe transition to a daylight. On all length of pedestrian crossings it is recommended to support constant high light exposure, horizontal and vertical. Even short foot tunnels require intensive artificial illumination as they have small cross-section section and a daylight in them quickly falls down. Large transitions to territories of shopping centres or underground do not concern objects of external illumination. Requirements to tunnel illumination contain in document DIN 67524, a part 1 and 2. For automobile tunnels brightness depending on intensity and speed of movement is normalized: from 100 to 250 kd/m2 at 50 km/h, from 160 to 320 kd/m2 at 80 km/h and from 250 to 400 kd/m2 at 100 km/h. These parameters concern the road and walls in height of 2 m from the earth. Change of brightness from entrance to a tunnel to departure should be coordinated with adaptive abilities of eyes. The regulation of brightness of a zone of entrance depending on natural external light exposure is provided with special control systems with photo gauges. Illumination of tunnels should be carried out professional lighting engineers. As each object is unique, requirements to illumination systems considerably differ.
Average horizontal light exposure of a road covering trafficway more than 60 m should be accepted parts of city transport tunnels in length in a day mode on tab. 1., and in evening and night modes equal 50 лк. At length of a tunnel to 60 m., average light exposure of a road covering should be 50 лк in all modes.
|
Длина тоннеля, м |
Наличие уклона спуска к |
Ориентация въездного портала |
Средняя горизонтальная освещенность, лк, на расстоянии от начала въездного портала, м |
|
|
порталу |
|
5 |
25 |
50 |
75 |
100 |
125 |
150 и более |
|
От 1 до 100
Более 100 |
Не учитывается
Без уклона
С уклоном |
Любая
Северная
Южная
Любая |
750
750
1000
1250 |
750
750
1000
1000 |
400
400
550
650 |
150
150
250
350 |
60
75
100
125 |
—
60
60
60 |
—
50
50
50 |
The note is in tab. 1. The course of decrease in levels of light exposure of consecutive sites of an entrance zone corresponds to requirements of creation of necessary conditions of adaptation of the driver driving to a tunnel.
Average horizontal light exposure of a covering passages under overpasses and bridges in a night-time should be not less than 30 лк at length of journey to 40 m, and at more length is accepted on norms of illumination of tunnels agrees tab. 1.
In transport tunnels fixtures with a protective corner not less than 10 ° should be applied. The height of their arrangement should be not less than 4 m.
For illumination of tunnels we recommend use of light-emitting diode fixture Sveteco 48 and L-INDUSTRY 36 (depending on a type of tunnel).
Sveteco 48 L-INDUSTRY 36
