Bright or Right?

Several weeks back I wrote about the embarrassing state of the city’s pedestrian lights. More specifically, I noted that we now have nine (9) different types of pdestrian lighting fixtures. You can read the details here. How we use the lights to reinforce the concept of a shared public realm is very important- but let’s be frank, this is not a life and death matter. The primary implications are for whether or not we are living up to our standard of excellence for the public realm, and whether or not the city and EPB are being efficient. It appears, however, that our pedestrian lights are potentially about to become more overtly harmful.

I speak of the new LED lighting fixtures that are about to be installed in all of downtown. On the face, this seems like a good thing- a standardized, networked series of efficient lights that can be remotely dimmed or brightened. In theory, this can save in electric costs, and provide emergency responders an extra tool to help them do their job more efficiently. The lighting company noted that even turned down to half output, the new fixtures are brighter than the existing fixtures. This is all good right? Not so fast my friend. From the things I have read (granted, I have no firsthand experience) the emphasis with the new lighting fixtures is on the technology- not on the act of providing good light. To wit, their claims speak of making lights brighter to increase safety and touting that the lights are brighter than the existing pedestrian lights. That all sounds well and good, but it actually exposes a fundamental lack of understanding of how human’s see or of empirical lighting research.

A decade ago, Councilman Littlefield tapped the Design Studio to draft a lighting ordinance for the City of Chattanooga. As we all know, shit rolls down hill, so this project fell into my lap. I won’t bore you with the details, but in the process of drafting a competent piece of legislation (if I do say so myself), I learned a great deal about the in’s and out’s of exterior lighting. That story ended when, after a robust stakeholder process and numerous revisions of the draft produced no controversy, the work was never brought to council for action. But I digress, back to the new lights.

The human eye is a wondrous, marvelous thing. But like anything, it has strengths and it has weaknesses. Its strength is that it can detect subtle nuance in very low lighting conditions. Think about what you can see when you wake up in the middle of the night and walk through the house. The reason you can see well in that case is that the eye is very good at adapting to low levels of light as long as the level of light is consistent. The weakness of the eye is that it does not do well with high contrast- a phenomenon we call glare. Think now about what happens when you open the fridge or someone turns a flashlight in your dark house- your eye adjusts to the brightest object and your ability to see other things in the room is severely degraded. With this understanding, the goal of exterior lighting should be to create even lighting, not necessarily bright lighting. In fact, bright lighting can actually impair visibility. So when we hear the lighting producers touting the brightness of their fixtures, it hints at a lack of understanding of what the ultimate goal is.

As of the time of my little ordinance experience, there was not a single study that made the correlation between lighting and increased safety. In fact, there are actually a number of studies that show that reduced lighting can actually reduce crime. There is, however, a substantial link between lighting and the perception of safety. It appears that we are afraid of the dark. In our quest to increase the perception of safety, however, it is quite possible to make places more dangerous. The first way this is possible lies with the way our eyes work. With increased lighting levels comes an increase in shadows and a decrease in the ability of a person to see everything in their environment. This creates places from criminal to hide, and places of darkness in which nefarious activities can occur undetected. The second potential danger is to drivers. As the pedestrian lights are typically installed near roads, the debilitating glare of over-bright fixtures makes it more difficult for drivers to see what is ahead of them. Obviously, visually impaired drivers are not a good thing.

It seems that the new lights are built around efficiency, sustainability, and cost savings. Those are worthy goals, but should be co-equal or secondary to what should be the first goal of lighting- to provide an excellent level of visibility. Beyond the reasons stated above, the charge can be further illustrated by the fact that the proposed fixtures are not shielded or cut-off. Shielded and cut-off fixtures reduce glare, ensure that fixtures are lighting what they are designed to, and reduce light pollution and urban sky glow. Frankly, it’s becoming increasingly difficult to even find non-shielded fixtures (TDOT even uses full cutoffs fixture for crying out loud).

Despite my earlier assertion that aesthetics are not a matter of life and death, they are indeed still important. If you consider that the lights are actually seen more during daylight hours when they are off than they are while illuminated at night, this is very real issue. As I wrote a few weeks ago, we have fixtures that were designed specifically for Chattanooga. This contributes to our authenticity and uniqueness. The components of the new lights seem to be chosen from a stock catalog and are likely produced in Asia- there is nothing unique or authentic about them. I had heard rumor that they are trying to retrofit their components to the standard fixtures- if this is indeed the case, hurrah!

All of that having been said, I think there is tremendous potential in a “smart” street lighting network. It is my sincere hope that the city, and/or EPB, and/or the manufacturer establish a set of best practices to ensure that we’re not actually doing more harm than good. If untrained individuals have the ability to adjust the lighting as they see fit, it is not inconceivable that downtown will be a glare bomb from dusk to dawn. If you have a chance, wait till it gets dark and take a trip to Frazier Avenue. The glaring lights that threaten to burn out your retinas are the new fixtures. Hopefully, this is not the future of downtown.

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