Public Survey Results

Transcription

1 Public Survey Results SFPUC conducted an online public survey and live demonstrations in January and February 2014 to better understand the public perception of the LED luminaires and adaptive lighting. Over a six week period, 71 participants completed the online survey, while over two nights 21 people attended live demonstrations of the Pilot Project and completed facilitated surveys at the completion of the demonstration. There were 44 Inner Sunset survey participants and 47 Presidio Heights participants. Live demonstrations in Presidio Heights ( Street) and the Inner Sunset ( Street) were conducted on January 22 and January 23, At each location, demonstrations were scheduled for 6:30 PM and 8:00 PM. The demonstration consisted of a brief presentation regarding the Pilot Project, and then a two block walk to observe the street lighting conditions within the Pilot Project area. At the 6:30 meeting, the LED lights were programmed to emit their full lumen output, and participants completed surveys based on the full output light levels for each system. At 8:00pm, the LEDs were dimmed to 50% of full input power, and participants completed surveys based on the dimmed light levels for each system. Through photometric measurements taken at each Pilot Project installation, SFPUC determined that operating fixtures at 50% input power resulted in a relative reduction in light output of slightly less than 50%, though the precise level of light output reduction varied from system to system. In order to solicit unbiased responses, the SFPUC did not inform the 8:00pm participants of the dimmed lights status until their surveys were submitted. A total of 14 people attended 6:30 meetings, and a total of 7 attended 8:00pm meetings. The small size of the data set has challenged the effort to draw definitive conclusions. Therefore, the data collected from the live demonstrations was aggregated with the data gathered through the online surveys. The conclusions presented in the following sections draw from both the public demonstration survey data and the combined survey data. These conclusions should be considered simple observations of collected survey data. No effort was made to control for sampling bias or any other effects to ensure the statistical significance of these results. General Impressions of LED Lighting SFPUC first analyzed overall impressions of the LED lighting, combining data from respondents observing dimmed and full output fixtures in both locations, including online survey results and facilitated survey results. The following report sections present the conclusions on overall perception of pedestrian safety, visual comfort, and light quality. As an overview of participant perceptions of LED lighting, approximately 60% of all participants agreed with the statement, I would like this style of lighting on my city streets. It should be noted that the pilot project did require the use of a single LED fixture, and thus four different LED luminaires were installed in the survey area. Responses to different LED fixtures varied. For example, impressions of one LED fixture installed on Street were significantly worse than impressions of the other three LED fixtures.

2 I would like this style of lighting on my city streets. 34% 60% 47% 49% 20% 71% Pedestrian Safety Both the Inner Sunset and Presidio Heights neighborhoods are relatively safe, as is evident by general agreement with the statement, It would be safe to walk here, alone, during darkness hours. Only 7% of all respondents disagreed with this statement. Focusing more specifically on the ability of the new LED lighting to adequately light the sidewalk for pedestrian safety, both at full output and when dimmed, respondents generally agreed with the statement, It would be safe to walk on the sidewalk here at night. Only 3% of all respondents disagreed with this statement. It would be safe to walk on the sidewalk here at night. 20% 74% The lighting enables safe vehicular navigation. 14% 10% 69% Visual Comfort SFPUC attempted to assess respondents general level of visual comfort by soliciting feedback regarding overall light levels and perceptions of glare. Of all the survey participants, 27% agreed or strongly agreed with the statement, There is too much light on the street and 31% agreed or strongly agreed with the statement, The light sources are glaring. These sentiments were not evenly distributed between the two sites as can be seen in the bar charts below.

3 There is too much light on the street. 64% 8% 27% 47% 10% 43% 83% 5% 10% The light sources are glaring. 53% 14% 31% 39% 12% 49% 68% 16% 11% Light Quality Although the technical assessment of the control systems did not explore issues relating to color rendering and light uniformity, some survey questions addressed these light quality metrics. Most respondents (61%) disagreed or strongly disagreed with the statement, I cannot tell the colors of things due to the lighting, while a smaller percentage agreed or strongly agreed with the statement (14%). Additionally, most respondents thought that the LED streetlights provided even lighting distribution (70% versus 13%). I cannot tell the colors of things due to the lighting. 61% 19% 14%

4 The light is uneven (patchy). 70% 14% 13% In terms of general impressions of overall quality, more respondents felt that the LED streetlights improved lighting relative to the incumbent streetlights (64% versus 33%). However, as with visual comfort issues, these sentiments were not evenly distributed between the two sites, with higher satisfaction coming from the Inner Sunset location. How does the overall quality and appearance of the new lighting compare to the previous lighting? 33% 64% 44% 54% 20% 75% Worse No Change Improved Dimming SFPUC grouped survey data across both installation sites, and including both the online survey and the facilitated survey, based on whether respondents were observing dimmed or full output LED streetlights in order to draw some preliminary conclusions regarding the impact of dimming on perception of public safety, visual comfort, and light quality. These results are presented in the following report sections. Pedestrian Safety Based on survey responses, dimming the LED streetlights did not negatively impact pedestrians sense of safety. Though predictably, fewer respondents found the lighting to be too bright when the lights were dimmed, and the percentage of respondents agreeing with the statement, there is not enough light on the street, did not increase when the lights were dimmed, and in fact decreased from 20% to 12%. Additionally, there was almost no discernible difference between survey responses to dimmed versus full output lights on issues of nighttime safety. To the statement, It would be safe to walk on the sidewalk here at night, 100% of the facilitated survey participants answered either neutral, agree or strongly agree both when the lights were full output, and when they were operating at 50% dimmed.

5 Visual Comfort Based on survey responses, dimming the lights resulted in increased visual comfort without compromising safety. A greater number of respondents agreed or strongly agreed with the sentiment The lighting is comfortable, when the lights were dimmed than when the lights were operated at full output (60% versus 48%). Similarly, the survey results appear to indicate that dimming increased public receptiveness to LED lights in place of the incumbent fixtures. When you compare responses to the statement, How does the overall quality and appearance of the new lighting compare to the previous lighting? 80% of those who were viewing dimmed lights reported that the LED lights were improved or much improved lighting. This compares to 60% of participants who viewed lights without dimming. Light quality Interestingly, dimming had conflicting impacts on respondents perception of the lights color rendering ability. Both the number of respondents that strongly disagreed and strongly agreed with the sentiment, I cannot tell the colors of things due to the lighting, increased. This may be linked to respondents perception of light distribution uniformity, where after the lights were dimmed, participants noticed a decrease uniformity. In responding to the statement, The light is uneven, the percentage of participants who agreed or strongly agreed with this statement increased from 17% to 29% when observing lighting in the dimmed state. Although in the past, lighting designers sought to achieve greater street lighting uniformity, recent lighting research has started to question the idea that more uniform lighting results in improved visual acuity.