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LIGHT TRESPASS ON HIGHWAYS

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TABLE OF CONTENTS

INTRODUCTION ....................................................................................... PAGE 1

DEFINING THE PROBLEM ....................................................................... PAGE 2

Spill Light ......................................................................................... PAGE 2

Glare ................................................................................................ PAGE 2

Temporary Construction Lighting ..................................................... PAGE 3

Golf Course Driving Range Lighting ................................................. PAGE 4

Tennis Court Lighting ....................................................................... PAGE 5

Sports Field Lighting ........................................................................ PAGE 6

Storage Yards and Building Floodlights ........................................... PAGE 7

Advertising Signs ............................................................................. PAGE 8

REDUCING LIGHT TRESPASS ................................................................ PAGE 9

LIGHTING PRODUCTS ........................................................................... PAGE 11

MINISTRY REQUIREMENTS ................................................................. PAGE 13

APPENDIX

1) EXAMPLES

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INTRODUCTION As the population grows and travel time increases more and more construction is being undertaken in close proximity to Highway’s. Typically commercial, industrial and recreational type developments are located close to a Highway. These developments often have nighttime activity which warrant’s lighting. If not properly specified and designed this lighting will often impact the Highway driver’s visibility.

Developments within 800m of a Provincial Highway require Ministry review and approval. In the past there was no Ministry review of the lighting component and no guidelines limiting the amount of light trespass on the roadways.

The high volumes of daytime traffic are warranting more and more nighttime roadway construction. This nighttime construction is forcing contractors to us portable floodlights to light their work sites. These lights generally do a great job of lighting the work site however often blind the drivers on the roadway.

The purpose of this document is to identify problem lighting installations in close proximity to the Highway, which may impact a driver’s visibility, and to develop guidelines aimed at reducing these impacts. Bright light sources may seriously affect a driver’s visibility because of disability glare. In addition, visual confusion created by extraneous light sources can affect the ability to locate and recognize signal lights. These bright light sources are typically extraneous to the roadway system and offer no benefit to the driver’s visibility on the roadway.

The document lists specific types of installations, which typically use high wattage luminaires and may impact the visibility of the Highway driver. Specific installations not listed shall meet the general intent of this document. The document only covers impacts on the drivers on roadways and does not cover impacts on residences and sky glow (up light).

The Illuminating Engineering Society of North America (IESNA), International Commission on Illumination (CIE) and the International Dark-Sky Association (IDA) are the leading authorities on lighting. We have therefore based much of this document on information from documents obtained from these organizations.

This document assumes that the reader has a good grasp of lighting terminology and design. The IESNA have documents explaining all lighting principals and terminologies. Such documents are:

• RP-33-99 Lighting for Exterior Environments • Lighting Handbook 9th Edition

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DEFINING THE PROBLEM If not properly controlled artificial lighting may be a hazard to the Highway driver. Uncontrolled lighting is typically referred to as light pollution. Where this uncontrolled lighting spills onto residences, roadways, etc it is referred to as light trespass. The International Commission on Illumination (CIE) defines light trespass as “Unwanted light, which because of quantitative, directional or spectral attributes in a given context, gives rise to annoyance, discomfort, distraction, or a reduction in the ability to see essential information”. From this definition it can be seen that light trespass may be caused by several characteristics of nighttime lighting. These include:

Spill Light

Spill light is defined as the Illuminance, which is produced outside of the area for which the luminaire is intended to light. Spill light is easily measured in its unit of measurement, Lux. Simply put it is the amount of light falling on the surface (typically the roadway). Spill light is typically of less concern than glare. It is however much easier to measure than glare.

Glare

The IESNA RP-16-96 defines glare as “the sensation produced by luminaire(s) within the visual field that is sufficiently greater than the luminance to which the eyes are adopted to cause annoyance, discomfort, or loss of visual performance and visibility”. In simple terms it is the light one view’s at its source. Glare is far the biggest source of concern. There are different levels of glare such as disability glare (most impacting), discomfort glare, and nuisance glare. For more detailed descriptions of glare refer to the IESNA Lighting Handbook. Glare is very subjective and difficult to measure on site.

AREA BEING ILLUMINATED

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Figure 1 – Examples of Glare and Spill Light

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Typically the most impacting lighting installations on Highway drivers are as follows:

Temporary Construction Lighting

Typically a cluster of very high wattage floodlights (400W to1000W Metal Halide) are mounted on a retractable arm, which mounts on a generator. The units are normally portable with wheels and can therefore be towed behind a truck. They are typically rented for a specific project. As a result of their portability the floodlights are at a very low mounting height (approximately 3 to 5m). These floodlights are normally fully aim-able. The Contractors are currently determining placement of these lights with their priority on the work area being lit, not the highway traffic. The combination of a very high wattage, low mounting height and close proximity to traffic along with a lack of placement guidelines create the potential for an extremely hazardous situation. One also has to keep in mind that even without the glare emitted from the temporary work lights road construction is often a hazard in itself for both drivers and workers.

Many contractors also believe that providing some spill light onto the roadway will benefit drivers. The problem is with the spill light comes glare, which actually reduces visibility. Simply put temporary work lights are not an acceptable substitute for proper roadway lighting and delineation devices such as reflective pavement markings, cones, flashers, etc.

Figure 2 – Examples of Temporary Lighting

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Golf Course Driving Range Lighting

Typically the luminaires for driving ranges are aimable floodlights mounted on the roof of the tee off area and the large posts (which often hold up the netting) down the sides of the range. For driving range lighting the priority is to illuminate the backside of the golf ball so the golfer can observe its flight from the tee off area. The floodlights are typically mounted close to the ground and therefore aimed more or less horizontally, which causes excessive glare outside the range. Driving ranges often use high light output 1000W or 1500W metal halide floodlights with little or no light control. These high wattage luminaires along with an often very low mounting height of approximately 7m to 14m and the very large area being illuminated often result in excessive spill light and glare on the Highway thus impacting driver visibility.

Figure 3 - Example of Golf Driving Range Lighting

The orientation of the range relative to the Highway is also critical. Ranges where the players are hitting away from the Highway will typically have lighting, which is less impacting on the Highway. Driving ranges using aim-able fixtures with glare control optics which are mounted on tall poles dramically reduce the spill light and glare. Lighting levels on the range may often have to be sacrificed to reduce spill light and glare cast onto the Highway

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Tennis Court Lighting

Tennis courts are typically illuminated with high output 1000W to 1500W Metal Halide aimable floodlights on 9m to 15m high poles around the exterior of the court. The low mounting heights (9m) typically cast excessive glare and spill light onto adjacent Highways.

Figure 4 – Example of Tennis Court Lighting

Tennis court lighting installations occasionally use full cut-off type fixtures. These installations are typically far less impacting than those with aimable fixtures. The use of full cut-off fixtures (Figure 13) is often a more expensive solution than using the aimable fixtures shown in Figure 4. Typically the problem with the aim-able fixtures is too low a fixture mounting height leading to excessive spill light and glare.

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Sports Field Lighting

Typically sports fields are used for football, soccer and baseball. These fields are normally very large in area, which require high output aimable floodlights mounted on 10m to 30m high poles positioned around the perimeter of the playing field. To date the main concern is the illumination levels and uniformities on the field with in many cases little or no attention paid to the adjacent Highways. Low fixture mounting heights are often used to reduce cost however they often reduce the quality of the lighting on the field and increase the spill light and glare off the field. Taller poles normally mean a more expensive installation.

Figure 5 - Examples of Sports Field Lighting

Typically a poor sports lighting installation uses low fixture mounting heights and floodlights with little or no glare control features as shown in the Figure 5 picture to the right. Where tall pole (above 21m) and fixtures with glare control features are installed the impact on the Highway is dramatically reduced. The Figure 5 picture to the left is an example of a good sports lighting installation with 24m high poles and fixtures with glare control optics. Even considering the large quantity of fixtures the lighting has minimal impact on the Highway adjacent to the field.

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Storage Yards and Building Floodlights

Typically these installations use off the shelf high wattage luminaires mounted at low mounting heights with little or no vertical cut off. The owner often selects a product based on low cost with no consideration to light trespass. For these installations security is the biggest issue therefore flooding the entire area (and those beyond) is often the result.

To reduce cost, high wattage off the shelf 400W to 1000W High Pressure Sodium and Metal Halide flood lights are often mounted at very low mounting heights on the sides of buildings or on wood poles. Often no lighting design or photometric analysis is undertaken of the aimable floodlights being used. They are normally field aimed by the installer with little or no consideration given to the glare and spill light cast onto the Highway.

Figure 6 – Examples of Storage Yard Lighting

The picture to the left in figure 6 shows a major storage facility with fixtures mounted on high mast style poles. The fixture glare control optics coupled with 45m mounting heights allow for high lighting levels with minimal impact on the Highway. The picture to the right shows a bad example of lighting a parking lot with aimable high wattage floodlights mounted on very low poles. The results are often very impacting on the Highway.

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Advertising Signs

Typically large advertising signs with external lighting and electronic neon, fibre-optic or LED type signs are generally more of a distraction than a source of light trespass. The intent of advertising sign is to draw the attention of motorists to their message.

Typically lower wattage sign luminaires are mounted on the top or the bottom of the sign. Glare is typically not much of a factor. The brightness may be a factor where large electronic signs are aimed at Highway traffic.

The size, position and luminous intensity (brightness) of the sign surface are all factors in evaluating its impact on Highway traffic. Generally the size, shape and look of large advertising signs are subject to Municipal approval.

Figure 7 – Example of Advertising Sign.

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REDUCING LIGHT TRESPASS There are literally hundreds of different luminaires on the market today. This coupled with numerous light sources such as high-pressure sodium; metal halide, etc make selecting the right luminaire the specifier’s greatest challenge.

The main way to reduce spill light and glare comes by using a qualified lighting designer during the design stage. The selection of proper fixture mounting heights and optical systems must be done with full consideration to not only the area being illuminated but also to the adjacent Highways. To do this requires analysis with suitable computer lighting design software. Through the use of today’s powerful computers and lighting programs a designer can assess spill light levels and glare levels and make adjustments to their designs. This design and analysis eliminates most of the guesswork and will normally eliminate the need for costly fixes.

It is important to note luminaires even from the same manufacturer have different optics and varying levels of cut-off. Luminaire suppliers all produce axial candlepower print outs, which can be used to access the luminaire cut off. These printouts typically show the vertical and horizontal candlepower emitted out of the luminaire in 5-degree increments. Review of these print-outs are critical in selecting a suitable cut off and mounting height.

Lighting suppliers will often provide computer lighting program, photometrics and analysis as part of the supply of their products. The key here is doing the required analysis and design up front prior to installing the equipment. Often when this analysis is not undertaken the results require costly repairs that may double and triple the cost of doing it right the first time.

Figure 8 - Luminaire Comparison

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Figure 8 shows some luminaires emitting more glare than others. In this test four different sports lights were mounted at identical mounting heights and aiming angles. From the pictures one can clearly see the difference in the glare emitted.

Typically full cut off fixtures are better than flood and sports lights in controlling light trespass over smaller areas. Larger areas such as sports fields and driving ranges typically require aimable sports lights to achieve the high light levels required for play.

Recommendations for reducing light trespass for some typical scenarios are as follows:

• Where lighting large sports field areas (such as baseball, soccer fields and driving ranges), which require very high lighting levels typically aimable, sports lights are required (See Figures 5 & 10). To reduce spill light and glare these sports lights shall not be aimed above 70 degrees from vertical. This shall involve selecting a suitable pole mounting height (typically not less than 21m). Remember higher mounting heights are typically better as the goal is aiming fixtures as downward as possible. External visors or other glare control devices shall be used on all flood and sports lights (See Figure 10). Where possible position pole so the lights are aiming away from the roadway.

• Where lighting small areas IESNA full cut off flat glass fixtures shall be used. This shall typically apply to car sales lots, parking lots, tennis courts, etc. Examples of full cut off fixture are shown in Figures 12, 13 and 14. Large storage yards and parking areas can also be lit effectively with full cut-off luminaires.

• Light trespass from temporary road construction lighting installations can be reduced by positioning and aiming the lights away from the Highway as shown in Figure 9 (left illustration). Floodlights shall be aimed so as to not be above 45 degrees above vertical as shown in Figure 9. Where the lights can’t be located as shown in Figure 9 (left illustration) then temporary glare screens shall be used. These glare screens shall be an opaque plastic material designed to shield the lighting from the eyes of the driver.

270°

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FIXTURES SHALL BE AIMED IN THE 45° TO 135° QUADRANTS ONLY

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Figure 9 – Positioning of Temporary Lighting Adjacent to a Highway

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LIGHTING PRODUCTS When it comes to large area and sports lighting projects two types of lighting should be considered. One type is the aimable type sports light as shown in Figures 10 and 11 (they are often referred to as floodlights). They are available in a range of different beam patterns ranging from narrow to very wide. These fixtures are typically aimed on-site to achieve the required lighting levels.

The other type is the full cut-off type. Full cut-off is an IESNA classification, which is defined as follows:

“A luminaire light distribution where zero candela intensity occurs at an angle of 90 degrees above nadir, and at all greater angles from nadir. Additionally, the candela per 1000 lamp lumens does not numerically exceed 100 (10 percent) at a vertical angle of 80 degrees above nadir. This applies to all lateral angles around the luminaire.”

To maintain a full cut-off classification a luminaire must be mounted with the optics facing down. Examples of full cut-off luminaires are shown in Figures 13 and 14.

Full cut-off luminaires are generally better than floodlights at controlling spill light and glare. They are however less flexible when it comes to illuminating large areas to very high levels.

Figures 10 to 15 show some good and bad examples of sports and area luminaires. We have commented below on what makes the products good or bad while not naming specific manufacturers. It is the responsibility of the designers to source out these or similar features, which will reduce light trespass.

Figures 10 and 11 (Sports Lights)

The luminaire shown in Figure 10 is an example of excellent glare control optics. These include external shielding, lamp guard, and internal baffles. All of these features are intended to reduce the light trespass.

The luminaires shown in Figure 11 is a floodlight with no glare control features.

When selecting a sports light it is critical to ensure the luminaire has glare control features similar to those shown in Figure 10. Floodlights as shown in Figure 11 with no spill light and glare control and are not acceptable.

Figures 12, 13 and 14 (Area Lighting)

The luminaires shown in figures 12, 13 and 14 all have excellent glare control optics for area lighting. The luminaires shown in Figures 13 and 14 have IESNA full cut-off (flat glass style) optics and do an excellent job in reducing spill light and glare. The Ministry typically uses the product shown in Figure 13 for roadway lighting.

The product shown in Figure 12 is half way between a floodlight and a full cut-off luminaire. With its forward throw optical system it is best suited for lighting large areas.

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Figure 15 shows aimable floodlight which has very poor spill light and glare control. These fixtures are typically installed at low mounting heights on buildings and utility poles and are not acceptable.

Figure 10 – Sports Light with glare control visor and lamp guard

Figure 11 - Sports light with no glare control

Figure 12 – Area luminaire with down ward throw optics

Figure 13 – Cobra head style luminaire with full cut-off optics

Figure 14 – Shoe Box style luminaire with cut off optics

Figure 15 – Area Floodlight with no glare control

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MINISTRY REQUIREMENTS It is critical that light trespass be reduced to acceptable levels on the Highways. With today’s powerful computers and calculation software the reduction of light trespass is best taken into account at the design stage prior to ordering the product. Typically, installations where the light trespass issues are not dealt with at the design stage can be very expensive to fix later.

All permanent installations are subject to Ministry Approval, where luminaires of 400W and greater are being used, they shall be thoroughly reviewed and signed-off by a Professional Engineer (approved by the Ministry Electrical Engineering Center) for conformance to the process and requirements listed below. The engineer shall be independent to the manufacturer. The process and requirements for Ministry approval of these lighting systems are as follows:

Installations with Cut-off Fixtures:

• All area lighting projects other than sports fields and driving ranges should use full cut-off or forward throw fixtures (See Figures 12, 13 and 14). Where full cut-off fixtures are used glare and spill light are not an issue and lighting calculations are not required unless specifically requested. Technical brochures, photometrics, pole locations relative to the Highway and mounting heights shall be submitted for review. The Ministry may request additional information.

Installations with Aimable Fixtures:

Sports Lighting installations (including driving ranges) typically require aimable sport lighting fixtures. The analysis required is therefore much greater than installations using full cut-off fixtures. Glare and vertical illuminace levels both require analysis.

• Glare Analysis – Glare is very subjective and difficult to measure in the field. It can however be analysed at the design stage. As part of the fixture and mounting height selection process the lighting designer shall review candlepower curves and select the appropriate luminaire mounting height and optical system so no greater than 12000 candlepower from any given luminaire is visible from the Highway (remember higher mounting heights are generally better). The 12000 candlepower level selected is approaching discomfort glare level and is typically possible to achieve. This is also the candlepower limit the automotive industry utilizes as the high limit for low beam headlights. Determining the angle between the maximum candlepower and the 12000 candlepower line can check this. This angle can then be applied to the aiming point on the area being lit to determine where the 12000 candlepower level cuts off relatively to the Highway. This is illustrated in Figure 16 below. Plan drawings shall be submitted showing aiming spots for each fixture and the point where the 12000 candlepower spot falls relative to the Highway. Each fixture shall show these two spots and shall note the fixture number and Nema beam spread (see Figure 16).

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12000 CANDLE POWER POINT SHALL NOT FALL ON HIGHWAY

AIMING POINT

AREA BEING LIT

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THIS DISTANCE SHALL BE DETERMINED BY USING AXIAL CANDLE POWER PRINTOUT AND AIMING DIAGRAM

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Figure 16 – Candlepower analysis

• Vertical Illuminance Levels – Unlike the glare analysis the lighting designer can calculate, but not measure the vertical illuminance levels can be calculated and for verification purposes can also be measured on site. The lighting designer shall undertake initial vertical illuminance calculations on a line along the edge of the roadway. Vertical levels at the edge of the roadway should not exceed 5 Lux. The levels should be calculated at 5m intervals at

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1.2m above the grade of the roadway. These levels shall be calculated using suitable computer lighting program and the manufacturers photometrics. The initial vertical levels shall be shown on a plan drawing which shows the pole, area being lit and the Highway (an example of a typical format for submittal is included in the Appendix). To ensure luminaires are properly aimed field-testing is critical. The engineer (or designated field technician) shall undertake field measurements with illuminance meter after the installation to confirm vertical levels at the edge of the Highway. These levels should be recorded on a drawing and issued to the Ministry Electrical Engineering Center for approval as soon as possible after the installation. Where levels exceed those listed above re-aiming and retesting shall be undertaken.

Temporary Construction Lighting:

• Temporary construction lighting shall be reviewed by the Ministry Representative for conformance to the recommendations noted in the Reducing Light Trespass section of this document. With the temporary nature of these installations and the various scenarios possible detailed lighting calculations are not practical.

Appendix

15561 - 109A Avenue, Surrey, BC Canada V3R 0Y2 Phone: 604.951.9020 Fax: 604.951.9028

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