JP4400359B2 - Road lighting system, road lighting method and road lighting device - Google Patents

Description

  The present invention relates to a road lighting system, a road lighting method, and a road lighting device in road lighting.

  Conventionally, in road lighting, a road lighting device in which a lamp is supported on the top of a pole has been used as a road lighting device (see, for example, Patent Document 1). Are arranged at predetermined intervals.

By the way, in road lighting, in general, in order to realize a sufficient visual recognition environment for an automobile driver, as an index value to be achieved, an average luminance L _AVE ≧ 1 cd / m ² and a total uniformity U _O ≧ 0. 4. An index value such as the axle line uniformity U ₁ ≧ 0.7 is set.
JP 2000-222911 A

  However, in the conventional road lighting device, it was not possible to reduce the number of lights of the road lighting device installed on the road while maintaining sufficient visibility for the driver. In detail, for example, when using a road lighting device of a conventional configuration, if the number of lights is reduced, the vicinity of the approximate center between the road lighting devices becomes darker, the average brightness and overall uniformity on the road, A value such as lane axis uniformity decreases, and sufficient visibility cannot be maintained.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a road lighting system, a road lighting method method, and a road lighting device that can reduce the number of lights while maintaining sufficient visibility. To do.

In order to achieve the above object, the present invention provides a road lighting device in which a road lighting device having a lamp attached to the top of a pole is arranged on the shoulder of the road at predetermined intervals along the road, and continuously illuminates the road. In the system, the lamp is configured to have a maximum luminous intensity vertical angle of about 70 ° to 75 °, and a midpoint of a transverse line that crosses a substantially middle point between adjacent road lighting devices in the width direction of the road. The luminance on the crossing line is reduced along the width direction with respect to the side on which the road lighting device is disposed, and the driving direction of the automobile is based on the crossing line. The lamp is configured to decrease the road surface brightness along the direction opposite to the road surface and increase the road surface brightness along the traveling direction.

  Further, the present invention is the above invention, wherein each of the road lighting devices is set such that a ratio of a height H of the pole and an arrangement interval S of the road lighting devices is S / H = 4.5-5. It is arranged along the road.

The present invention is characterized in that, in the above invention, the overall uniformity on the crossing line is 0.4 or more, and the lane axis uniformity of the road is 0.7 or more.

  Further, the present invention is the above invention, wherein the lamp includes a light source and a cup-shaped reflecting plate in which the light source is disposed, and the light source is disposed inside the reflecting plate so that the optical center is deep. It is arranged.

  Moreover, the present invention is characterized in that, in the above-mentioned invention, an undercut shape having a diameter reduced toward the inside is provided at an opening end of the reflecting plate.

In order to achieve the above object, the present invention continuously illuminates the road by arranging a road lighting device having a lamp attached to the top of the pole at a predetermined interval along the road on the shoulder of the road. In the road lighting method, the maximum luminous intensity vertical angle of the lamp is set to about 70 ° to 75 °, and the light distribution of the lamp is traversed in the width direction of the road at a substantially middle point between adjacent road lighting devices. The brightness at the midpoint of the crossing line is the average brightness to be achieved, the brightness on the crossing line is reduced along the width direction with respect to the side where the road lighting device is disposed, and the crossing line is used as a reference. The road surface brightness is gradually decreased along the direction opposite to the traveling direction of the automobile, and the road surface brightness is gradually increased along the traveling direction.

  According to the present invention, it is possible to reduce the number of lamps while maintaining sufficient visibility.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a road lighting device 1 according to the present embodiment and a road 2 on which the road lighting device 1 is installed. As shown in FIG. 1, the road lighting system 100 includes a plurality of road lights arranged at predetermined intervals (spans) S along the road 2 on the shoulder of one side of the road 2 having a road width B of 7 meters, for example. The apparatus 1 is provided, and the road 2 is continuously illuminated by these road illumination apparatuses 1. The road lighting device 1 is configured by fixing a lamp 3 to the top of a pole (post) 4, and a lamp as a light source provided in the lamp 3 is the same as a conventional lamp. In addition, a reflector having a light distribution characteristic that is symmetrical about the lamp 3 in the traveling direction of the road 2 is used for the reflector of the lamp 3. Specific configurations of these lamps and reflectors will be described in detail later.

In the present embodiment, each of the road lighting devices 1 is set so that the S / H ratio is about 5 while the height H of the pole 4 (the arrangement height of the lamp 3) H of the road lighting device 1 is 10 meters, for example. With a span S of about 50 meters. That is, in the present embodiment, the road lighting device 1 is arranged with a wider span than conventional general road lighting having an S / H ratio of about 3.5. As described above, when the road lighting device 1 is arranged with a wide span, an automobile such as an average luminance L _AVE ≧ 1 cd / m ² , an overall uniformity U ₀ ≧ 0.4, and an axle line uniformity U ₁ ≧ 0.7. However, in the present embodiment, the light distribution of the road lighting device 1 is set as follows by maintaining the index value for ensuring sufficient visibility for the driver of the vehicle. It is possible to maintain the index value.

That is, as the first point, the maximum luminous intensity vertical angle θ of the lamp 3 is made larger than the conventional one, and as the second point, the middle of the two adjacent road lighting devices 1 is arranged in the width direction of the road 2. On the crossing line C (see FIG. 2) that traverses, the light distribution is determined so as to achieve the above average luminance L _AVE and overall uniformity U ₀ , and the direction of travel of the vehicle with respect to the crossing line C as a reference. The road surface brightness is gently decreased along the facing direction (indicated by the arrow X in the figure), and the road surface brightness is gently increased in the direction along the vehicle traveling direction (indicated by the arrow Y in the figure). (See FIG. 4).

  The first point will be described in detail. Generally, when the span S of the road lighting device 1 is widened, the road surface brightness near the crossing line C is reduced, and the overall uniformity and the lane axis uniformity are reduced. Become. Therefore, the maximum luminous intensity angle vertical angle θ of the lamp 3 is set to about 70 ° to 75 °, and the maximum luminous intensity angle vertical angle is made larger than that of the conventional one, so that the irradiation light is further increased along the running direction of the road 2. By making it reach far, irradiation light can reach the crossing line C, and the road surface brightness near the crossing line C can be improved. At this time, the light intensity assigned to the maximum light intensity angle vertical angle θ is defined by the road surface brightness at the transverse line C to be realized.

By the way, although the illuminance near the transverse line C can be increased by increasing the maximum luminous intensity angle vertical angle θ of the lamp 3 as described above, especially when the maximum luminous intensity angle vertical angle θ is increased, When the luminous intensity at the maximum luminous intensity angle vertical angle θ is increased, the luminance distribution of the road 2 becomes inappropriate and the glare (TI value) increases accordingly. Further, the index values such as the average luminance L _AVE , the overall uniformity U ₀ , and the axle line uniformity U ₁ are not always achieved by the configuration described in the first point.

Therefore, in order to achieve the index values such as the above average luminance L _AVE , total uniformity U ₀ , and axle line uniformity U _l while suppressing glare, the luminance distribution in the road section between the adjacent road lighting devices 1 is described above. The light distribution of each lamp 3 of the road lighting device 1 is controlled so that the luminance distribution described in the second point is obtained.

The configuration of the second point will be described in detail. As shown in FIG. 2, the road section between two adjacent road lighting devices 1 is divided into 10 equal intervals with a width h along the traveling direction, and is equally spaced with a width i along the width direction. Consider the luminance at each dividing point when the number is divided into ten. At this time, a location where the middle of the two road lighting devices 1 crosses the width direction of the road 2 is defined as the crossing line C described above. In addition, m = −1, m = −2,..., M in order with respect to the transverse line C with respect to each transverse line located in the direction opposite to the traveling direction (arrow X) as viewed from the transverse line C. = -5 and numbers are assigned to each transverse line located in the traveling direction (arrow Y) when viewed from the transverse line C, in order, m = 1, m = 2,..., M = 5. I will attach it. In addition, the dividing lines that divide the width direction of the road 2 are numbered n = 1, n = 2,..., N = 10 in order from the side where the road lighting device 1 is arranged. To. The coordinates of each dividing point are expressed as (m, n), and the luminance at the dividing point (m, n) is expressed as L _{m, n} .

First, the luminance is determined so as to achieve the above average luminance L _AVE and overall uniformity U ₀ on the transverse line C, which is the midpoint of the road section between two adjacent road lighting devices 1. . That is, the distribution of the road lighting device 1 is set so that the luminance L _{0, n} at each dividing point (0, n) on the transverse line C becomes a luminance distribution according to the following equations (1) and (2). Control the light.

L _{0, n} = a (n × i−0.5B) + L _ave (1)
a = (U ₀ −1) L _ave /0.45B (2)

The expression (1) will be described. Generally, on the crossing line C, the distance decreases from the starting point C ₀ (n = 0) on the side where the road illumination device 1 is arranged toward the ending point C _e (n = 10). . Therefore, in the present embodiment, as shown in FIG. 3, the brightness L ₀ and ₅ at the center point C _c (n = 5) in the width direction on the transverse line C is set to the average brightness L to be achieved. _The linear expression of the expression (1) is determined so as to have the same value as _ave, and thereby the overall average brightness in the transverse line C becomes the average brightness L _ave .

Further, the expression (2) will be described. Generally, the total uniformity is obtained by (average luminance in the area) / (minimum luminance in the area). That is, in order to set the overall uniformity on the transverse line C to the above-described overall uniformity U ₀ , the minimum luminance on the transverse line C may be set to the overall uniformity U ₀ × average luminance L _ave . As described above, the luminance becomes the minimum in the transverse line C, and an endpoint C _e of the transverse line C (n = 10), when calculating the overall uniformity of a certain area, in the area It is common to calculate without including the edge. Therefore, in the present embodiment, the overall uniformity U ₀ is achieved in the range of n = 1 to 9 on the transverse line C, and n = 9.5 where the luminance is minimum at n = 1 to 9. At this point, the luminances L _{0 and 9.5} are U ₀ × average luminance L _ave . From the above, on the transverse line C, the luminance L _0,5 at the point of n = 5 (0.5B) is the average luminance L _ave , and the luminance L at the point of n = 9.5 (0.95B). _{When the} luminance distribution on the transverse line C is expressed by a linear expression so that _{0 and 9.5} are U ₀ × average luminance L _ave , the slope a is (U ₀ −1) L _ave /0.45B.

In this way, if the light distribution is controlled so that the luminance distribution L _0n on the transverse line C follows the equations (1) and (2), the average luminance and the total uniformity on the transverse C are set to the average luminance L described above. It is possible to set _ave and total uniformity U ₀ .

In addition, after determining the luminance distribution on the crossing line C as described above, the road surface luminance is gently reduced along the direction (indicated by an arrow X in the figure) opposite to the traveling direction of the vehicle with respect to the crossing line C. The lane axis uniformity U _l can be achieved by decreasing the luminance and increasing the luminance gently in the direction along the traveling direction of the vehicle (indicated by an arrow Y in the figure).

More specifically, with respect to the brightness L _{0, n} of the point n on the transverse line C, each division point (m, n) along the direction (indicated by the arrow X in the figure) opposite to the traveling direction of the automobile is shown. Luminance L _{m, n}
L _{m-1, n} = K _L × L _{m, n} (m = 0, -1,... -5)
K _L is a constant satisfying 0 <K _L <1 (for example, K _L = 0.8 to 0.9)
And the brightness L _m , _{n of} each dividing point (m, n) along the traveling direction of the vehicle (indicated by arrow Y in the figure) with respect to the brightness L _{0, n} of the point n on the transverse line C The
L _{m + 1, n} = K _R × L _{m, n} (where m = 0, 1,..., 5)
K _R is a constant satisfying 1 <K _R (for example, K _R = 1.2 to 1.3)
It is said. As a result, the luminance along the lane axis of the road 2 gradually increases from the left side to the right side of the road 2 with the transverse line C as the center, and the above-described total uniformity U ₁ is achieved.

As described above, the luminance distribution in the road section between the two adjacent road lighting devices 1 is determined, and for example, the light distribution of the road lighting device 1 so as to form the luminance distribution as shown in FIG. By controlling the above, the road illumination device 1 is arranged with a wide span S, and the index values such as the average luminance L _AVE , the overall uniformity U ₀ , and the axle line uniformity U ₁ are achieved. It becomes possible to suppress it.

  Next, the configuration of the lamp 3 of the road lighting device 1 will be described with reference to FIGS. As shown in these drawings, the lamp 3 includes a reflecting mirror 30 disposed inside a lamp main body (not shown) and a lamp 40 as a light source disposed inside the reflecting mirror 30. The reflection plate 30 has a lower surface (a surface that faces the ground when the lamp is installed) opened, and is configured in a bilaterally symmetric shape in the traveling direction as a whole.

  The reflecting plate 30 will be described in more detail. The reflecting plate 30 is formed of a metal plate (for example, an aluminum plate) having a predetermined reflectance with respect to the light of the lamp 40, is formed in a cup shape that covers the lamp 40, and has an internal structure. The light of the lamp 40 arranged at the position is reflected toward the road 2. Specifically, the reflecting plate 30 includes a reflecting surface 31A formed on the rear side of the lamp 40, that is, on the socket side to which the lamp 40 is connected, a reflecting surface 31B formed along the circumferential direction of the lamp 40, the lamp 40 in the direction of the front end of the vertical axis, that is, the reflecting surface 31C formed on the surface facing the reflecting surface 31A is integrally connected, and is reflected toward the width direction of the road 2 by the reflecting surfaces 31A and 31C. Light is irradiated, and irradiation light is irradiated toward the running direction of the road 2 by the reflecting surface 31B.

The lamp 40 has a substantially cylindrical arc tube 41, and is arranged so that the vertical axis 42 of the lamp 40 overlaps the left-right symmetric axis of the reflector 30. Thereby, the illumination light of the lamp 3 is irradiated symmetrically about the lamp 3 in the traveling direction of the road 2. In the present embodiment, for example, a 180 watt (1900 lumen) sodium lamp, which is a lamp having a wattage substantially the same as that of the conventional lamp, is used as the lamp 40. Thus, when the wattage of the lamp of the lamp 3 is not changed from the conventional one, when the span S of the road lighting device 1 is widened, sufficient brightness to achieve the above average brightness _Lave is obtained. However, in this embodiment, sufficient luminance is obtained as follows. That is, in the present embodiment, as shown in FIG. 9, the lamp 40 is arranged in the reflector 30 so that the lamp 40 is directed toward the bottom of the reflector 30 so that the optical center is deeper than the conventional arrangement position 32A. Thus, the arrangement position 32B is changed by a predetermined distance d. As a result, more luminous flux is reflected by the reflector 30 and the illumination efficiency is improved. Therefore, even when the road illumination device 1 is arranged with a wide span, the wattage of the lamp 40 is not increased. High brightness can be secured.

  As described above, the traveling direction of the road 2 is irradiated with the reflected light reflected by the reflecting surface 31B. Specifically, as shown in FIGS. 6 to 8, the inner surface of the reflecting surface 31B is formed in a shape in which a plurality of reflecting portions 31B1... 31Bn are connected in a stepped manner, and each reflecting portion 31B1. At 31 Bn, the light from the lamp 40 is reflected and irradiated toward the direction of travel of the road 2. At this time, the reflecting portion 31Bn located on the opening end 33A side reflects light farther in the running direction than the reflecting portion 31B1 located on the bottom portion 33B side. That is, the maximum luminous intensity angle vertical angle θ is defined by the reflecting portion 31Bn located at the opening end 33A.

  In general, as shown in FIG. 10, the reflecting surface 31B is formed in a shape that gradually widens from the bottom 33B to the opening end 33A, but in this shape, the maximum luminous intensity angle vertical angle θ is about 60 °. In this embodiment, the maximum luminous intensity angle vertical angle θ of 70 ° to 75 ° cannot be achieved.

  Therefore, in the present embodiment, for example, as shown in FIG. 8, a shape in which the reflecting portion 31Bn located at the opening end 33A of the reflecting surface 31B is bent inward and the opening end 33A of the reflecting plate 30 is reduced in diameter. As a so-called undercut shape, the maximum light intensity angle vertical angle θ is expanded to approximately 70 ° to 75 ° by widening the incident angle of light from the lamp 40 to the opening end 33A. Thereby, reflected light can be made to reach | attain far from the running direction of the road 2, and it becomes possible to arrange | position the road illuminating device 1 by the wider span S than before.

Moreover, in this Embodiment, the reflective area of each reflection part 31B, ..., 31Bn of the reflective surface 31B of the reflecting plate 30 is adjusted, and each division | segmentation point (m, n) (refer FIG. 2) of the road 2 is adjusted. By adjusting the amount of light to be irradiated, the average luminance and the overall uniformity on the transverse line C are set to the above-described average luminance L _ave and the overall uniformity U _0, and the automobile is based on the transverse line C. The light distribution characteristic is formed such that the road surface luminance is gently decreased along the direction opposite to the traveling direction of the vehicle and the road surface luminance is gently increased along the traveling direction.

  The manufacturing process of such a reflecting plate 30 will be described. First, a cup shape is formed by performing deep drawing on a flat plate serving as a base material of the reflecting plate 30, and the reflecting surfaces 31A to 31C are formed. At this time, in order to prevent breakage or the like from occurring at the joint portions of the reflecting portions 31B1... 31Bn, the plurality of molds are sequentially formed so as to form a relatively deep cup shape from a relatively shallow cup shape first. Use to form in steps. In this deep drawing, the shape of the cup portion is such that the diameter gradually increases from the bottom 33B to the opening end 33A without reducing the diameter of the opening end 33A as shown in FIG. To form.

  Next, in order to make the opening end 33A of the reflecting surface 31B into an undercut shape, an inner frame for reducing diameter configured to be disassembled is disposed inside the cup portion, and the opening end 33A is pressed from the outside of the cup portion. The diameter of the opening end 33A is reduced. After the diameter of the opening end 33A is reduced, the reduced diameter inner frame is disassembled and taken out from the cup portion. Through the above steps, the reflecting plate 30 in which the open end 33A of the reflecting surface B is formed in an undercut shape is integrally formed.

  Thus, by integrally molding the undercut portion of the reflecting plate 30, for example, the reflection angle of the reflected light can be controlled with higher accuracy than when a reflecting member for undercut is separately attached to the reflecting plate 30, for example. It becomes possible.

As described above, according to the present embodiment, the lamp 3 is configured to have a maximum luminous intensity vertical angle of about 70 ° to 75 °, and a substantially middle point between adjacent road lighting devices 1 is set. The average brightness and the overall uniformity on the crossing line C crossing in the width direction of the road are equal to the average brightness L _ave to be achieved and the overall uniformity U _0, and the crossing line C is used as a reference. The road lighting device 1 is arranged with a wide span S because the lamp 3 is configured to gently decrease the road surface brightness along the direction opposite to the traveling direction of the car and increase the road surface brightness along the traveling direction. However, it is possible to achieve index values such as the above average luminance L _AVE , total uniformity U ₀ , and axle line uniformity U ₁ , and to further suppress glare. As a result, it is possible to reduce the number of lamps to be arranged on the road 2 while maintaining sufficient visibility.

  Further, according to the present embodiment, each of the road lighting devices 1 is adjusted so that the ratio of the height H of the pole 4 and the arrangement interval S of the road lighting devices 1 is S / H = 4.5-5. Since it is arranged along the road 2, for example, if the height H of the pole 4 is set to the same level as the conventional one, the road lighting device 1 can be arranged with a span S wider than the conventional one.

  Here, even when a conventional lamp is used, the number of lamps can be reduced while irradiating the entire road if the height H of the pole is increased to widen the irradiation range. Then, as the pole becomes higher, the cost of the pole increases, and the construction cost and maintenance cost required for installing the road lighting device also increase. On the other hand, according to the present embodiment, it is possible to expand the irradiable range in the running direction of the road 2 and reduce the number of lights without increasing the height H of the pole 4. Moreover, if the configuration is such that the height H of the pole is simply increased, the irradiation range also extends in the width direction of the road 2 and there is a risk of adversely affecting the environment around the road (so-called light pollution). On the other hand, according to the present embodiment, since the irradiable range is mainly expanded toward the direction of travel of the road 2, the environment around the road is not adversely affected.

  In addition, according to the present embodiment, since the lamp 40 is disposed inside the reflector 30 so that the optical center is deeper, more luminous flux is reflected by the reflector 30, so that the illumination efficiency is improved. Even when the road lighting device 1 is arranged with a wide span, sufficient luminance can be ensured without increasing the wattage of the lamp 40. Thereby, the cost of the lamp 40 can be suppressed.

  In particular, the lamp 40 is arranged inside the reflector 30 so that the center of the light is deep, and the lamp 3 is configured to have a maximum luminous intensity vertical angle of about 70 ° to 75 °. The light flux obtained by the improvement can be distributed to the far side of the road 2 in the direction of travel, and the far side of the road 2 can be effectively irradiated.

  In addition, according to the present embodiment, after forming a cup shape for deep drawing on a flat plate, the diameter of the opening end 33A is reduced toward the inside, and the undercut shape is integrally formed with the opening end 33A. Since the reflecting plate 30 is formed, for example, the reflection angle of the reflected light can be controlled with higher precision than when a reflecting member for undercut is separately attached to the reflecting plate 30.

  It should be noted that the above-described embodiment is merely an aspect of the present invention, and can be arbitrarily modified within the scope of the present invention.

It is a figure which shows the structure of the road lighting system which concerns on embodiment of this invention. It is a figure for demonstrating the luminance distribution on a road. It is a figure for demonstrating the luminance distribution in the midpoint of adjacent road lighting apparatuses. It is a figure which shows the one aspect | mode of the luminance distribution on a road. It is a top view which shows the structure of a lamp. It is a side view which shows the structure of a lamp. It is a perspective view which shows the structure of a lamp. It is sectional drawing which shows the structure of a lamp. It is a figure for demonstrating arrangement | positioning of a lamp | ramp. It is sectional drawing which shows the shape of the conventional reflecting plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Road illuminating device 2 Road 3 Lamp 30 Reflector 31A-31C Reflective surface 33A Open end 40 Lamp B Road width C Transverse line θ Maximum luminous intensity angle Vertical angle

Claims (7)

In a road lighting system in which a road lighting device having a lamp attached to the top of a pole is arranged on the shoulder of the road at a predetermined interval along the road, and continuously illuminates the road,
Configuring the lamp to have a maximum luminous intensity vertical angle of about 70 ° to 75 °;
The luminance at the midpoint of the transverse line that crosses the substantially middle point between adjacent road lighting devices in the width direction of the road is set to the average luminance, and the luminance on the crossing line is arranged on the road lighting device. The road surface brightness is decreased along the width direction with respect to the side, and the road surface brightness is decreased along the direction opposite to the traveling direction of the automobile with respect to the transverse line, and the road surface brightness is increased along the traveling direction. A road lighting system comprising the lamp.   Each of the road lighting devices is arranged along the road so that a ratio between a height H of the pole and an arrangement interval S of the road lighting devices is S / H = 4.5-5. The road lighting system according to claim 1. 3. The road lighting system according to claim 1, wherein the overall uniformity on the crossing line is 0.4 or more, and the lane axis uniformity of the road is 0.7 or more. The lamp includes a light source and a cup-shaped reflector in which the light source is disposed,
The road lighting system according to any one of claims 1 to 3, wherein the light source is arranged inside the reflector so that the center of light is deep.   The road lighting system according to claim 4, wherein an undercut shape that decreases in diameter toward the inside is provided at an opening end of the reflecting plate. In the road lighting method for continuously illuminating the road by arranging a road lighting device with a lamp attached to the top of the pole at predetermined intervals along the road on the shoulder of the road,
The maximum luminous intensity vertical angle of the lamp is about 70 ° to 75 °,
The light distribution of the lamp is an average luminance that should achieve the luminance at the midpoint of the transverse line that crosses the substantially middle point between adjacent road lighting devices in the width direction of the road, and the luminance on the transverse line is Decrease along the width direction with respect to the side on which the road lighting device is arranged, and gently reduce the road surface brightness along the direction opposite to the driving direction of the car with respect to the crossing line. A road lighting method characterized by gradually increasing the road surface brightness along the road. In a road illuminating device configured to attach a lamp having a light source and a reflector to the top of a pole and illuminate the road by being arranged at predetermined intervals along the road on the shoulder of the road,
After forming a cup shape for deep drawing on a flat plate, the diameter of the opening end is reduced toward the inside, an undercut shape is formed integrally with the opening end, and the reflector is formed. The luminous intensity vertical angle is about 70 ° to 75 °,
The reflector has an average luminance that should achieve a luminance at a midpoint of a transverse line that crosses a substantially middle point between adjacent road illumination devices in the width direction of the road, and the luminance on the transverse line is the road illumination. Decrease along the width direction with respect to the side where the device is arranged, and gently reduce the road surface brightness along the direction opposite to the driving direction of the car with respect to the transverse line, along the driving direction. A road lighting device characterized by having a light distribution characteristic that gently increases road surface brightness.

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