Lighting : LIGHTING-April-2017
46 LIGHTING MAGAZINE | April/May 2017 Minimum Approach Sight Distance Table 3 is an excerpt of Table 15.1 from the New Zealand Transport Agency (NZTA) Pedestrian Planning and Design Guide3. It gives an indication “how far” away a driver should be able to see a person on the pedestrian crossing in order to stop the vehicle safely. Highlighted values in Table 3 shows that the minimum approach sight distance for a New Zealand urban road with 50km/h speed limit is 40m, under emergency braking and with adequate skid resistance. Table 2. Reduction in energy consumption (combined installations) Project Stage Luminaire Type Luminaire Quantity Total Wattage (W) Before Upgrading 125WMV 44 150WMH 2 After Upgrading 55WLED 42 77WLED 4 Table 3. Minimum Approach Sight Distance3 Speed (km/h) Approach Sight Distance (m) Rural Urban Normal R=2.5s Alerted R=2s R=1.5s 10 N/A 6 5 20 14 11 30 23 19 40 35 30 50 45 40 60 65 55 70 85 70 80 115 105 95 R = Driver’s reaction speed INSTALLATION COMPARISON Before upgrading Figures 4, 5 and 6 show a pedestrian using a crossing with its original lighting. The crossing is on a Category P3 road (local) with 50km/h speed limit and a minimum approach sight distance 40m. The photographs were taken at 10:14 pm on Tuesday, 20th October 2015. The weather was fine with an ambient temperature of 10°C, relative humidity of 70% and good visibility. The viewer point was approximately 25m from the crossing. No illuminance measurements were taken of the existing lighting. The following comments are a visual appraisal of the seeing conditions at the crossing. The horizontal illumination revealed the crossing markings on surface; they were distinguishable by road users. There was limited surround illumination (horizontal and vertical) to the crossing; a pedestrian at the verge of the crossing was difficult to see and might not be noticed by drivers viewing from a safe stopping distance (see Figures 4 and 6). There was limited surround illumination (horizontal and vertical) to the crossing; a pedestrian at the verge of the crossing was difficult to see and might not be noticed by drivers viewing from a safe stopping distance.