Source: Fairfax County, VA
Consider the following proposal. Instead of installing regular overhead streetlights, I proposed to light the road and adjacent sidewalk with spotlights, aimed directly into the eyes of oncoming drivers.
Technically, those spotlights could achieve sufficiently high light levels on the road and sidewalk surface to meet any normal standard for road illumination. And if that’s as far as you look, then you wouldn’t necessarily see anything wrong with this proposal.
And yet, we all know this would be a spectacularly stupid way to light a road. Having the lights shine directly into the drivers eyes would blind them. Drivers would be able to see pedestrians on the sidewalk and in the street crossings better if you turned off those spotlight street lights entirely.
From the perspective of the drivers, those spotlight street lights actually dis-illuminate the sidewalk and pedestrian crossings. They make it less visible, because the direct glare from the light overpowers whatever modest amounts of light are reflected off pedestrians in the sidewalk and street-crossing areas.
So nobody would use bright, glaring lights, directed into oncoming traffic, as street lighting.
Or would they?
East side versus west side of Vienna
Source: Streetlights.info.
Maple Avenue west of Courthouse is illuminated with standard “cobrahead” streetlights. These sit high above the street — maybe 25′ above Maple Avenue. They direct their light downward, and the most recent (LED) versions directly literally all their light downward, and so are “dark sky compliant”. Nearby street lights are well above the line-of-sight of anyone driving down Maple Avenue.
Source: Pole light store.
Maple Avenue east of Courthouse is illuminated with acorn lights. These sit approximately 14′ above the road, and cast light in all directions. Nearby streetlights are directly in the line-of-sight when automobile drivers look to see whether pedestrians are on the sidewalk or in the crosswalks.
Last night, around 8 PM, as I drove down Maple Avenue in Vienna, I got lesson in just how poor the road lighting is on the east (acorn) side of town, compared to the west (cobrahead) side.
The important points are that
- It was fully dark.
- There was almost no traffic (so almost no light from auto headlights).
- There were a lot of pedestrians, both on the sidewalk and jaywalking.
On the west (cobrahead) side of town, I had no problem seeing the sidewalks. On the east (acorn) side, I could barely make out the sidewalks. I could vaguely see that there were people on those sidewalks. But it was as if the sidewalks were in shadow.
But the sidewalks weren’t in shadow. I’m sure they appeared well-lit to the pedestrians themselves.
The problem was the glare from the acorns. Without the additional lighting from car headlights, the line-of-sight glare from those acorn lamps swamped the light reflected off the pedestrians on the sidewalk. The pedestrians were so much darker than the lights themselves that when they were both in my line of sight, I almost literally couldn’t see the pedestrians. All I could make out were some vague, dark shapes.
Yes, it’s a geezer thing, but it’s not exclusively a geezer thing.
The glare hazard from acorn lights is well known. Let me quote one expert at length:
Keep in mind, these globe-type fixtures are often cheap plastic replicas of the ornate glass fixtures made popular in the 1920s, when they had the equivalent light output of today’s living room lamps. It is embarrassing that manufacturers have increased by 10-50 times the light output of these “decorative” fixtures, resulting in “glare bombs”. Then they sell them as streetlights to city transportation departments eager to maintain the “look and feel” of a historical period with little regard for the impact on driver and pedestrian visibility. Using a lighting fixture that temporarily blinds drivers and pedestrians is the epitome of bad lighting design, yet we see the numbers increasing in every major city. In many cases, historic preservation groups – unwilling or unable to understand the impact glare has on visibility – force the decision on DOT staff. The widespread use of these decorative fixtures as streetlights is evidence that cities often pay far less attention than they should to quality lighting design and real safety concerns.
Source: Volt.org
In one relevant example, consultants for the City of Pittsburgh, PA recommended that the city get rid of all of its acorn fixtures during their conversion to LED lighting. In their opinion, there was no way to reduce the glare from those fixtures adequately. See below, emphasis mine:
›› The light sources and the luminaires both must be replaced because the standard City luminaires do not have reflectors or lenses to control glare. Cobra head, shoe box, and pendant luminaires can be replaced with new models that have the proper characteristics. However, the team recommends that acorn luminaires not be retrofitted because it is not possible to control glare or dark sky impact with a fixture that radiates light in all directions. Acorns should be phased out of the City inventory just as the obsolete globe luminaires have been discontinued.
Source: City of Pittsburgh, “LED Street Light Research Project”, Remaking Cities Institute, Pittsburgh, Pennsylvania September 2011
The glare is so annoying (even to non-geezers) that some city ordinances specifically regulate acorns near housing. An example is Orange County, Florida. There, any acorn fixture within 80′ of a residential property line has to have permanent opaque shielding to prevent light trespass (emphasis mine):
" ... Acorn-style light fixtures located within eighty (80) feet of property zoned as single family residential shall incorporate opaque shielding on the inside of the globe's surface, which internal shielding shall be field-adjusted to minimize off-site light intrusion onto any adjacent property.
Source: Orange County Florida.
Admittedly, this problem with glare gets worse as your eyes age. Just google elderly driving glare and you’ll see a host of articles. Here’s one that’s more on the scientific side of just which components of vision are the first to go (reference). Sensitivity to the blinding effects of glare is one of the main reasons that some older people have difficulty driving at night.
I’m not sure that I noticed it last night because I’m getting old (turning 64 this month), or because the conditions were right for it — dark night, no auto traffic, lots of pedestrians. For sure, I don’t have this problem on the west (cobrahead) side of town, there the streetlights are placed well out of the line-of-sight of the drivers. I only have it on the east (acorn) side, and then, only when there is no supplementary lighting from car headlights.
So, I’d say the preponderance of evidence is that it’s mostly a problem of using acorn lights as street lights. Perhaps compounded by aging.
How do I hate thee, let me count the ways.
In no particular order, here’s my list of additional reasons to dislike acorns, beyond the glare hazard.
One: Light pollution. Need I say more? The Town bought these things before light pollution was even on the radar screen for most of us.
Source: The International Dark-Sky Association:
Two: High energy use. I did this calculation years ago, in one of my prior anti-acorn screeds. Best guess, these acorns use about four times as much energy as would be used by cobrahead fixtures. Unsurprising, really, since you start out by shooting about 40% of your light off into the sky.
Three: High maintenance burden. Instead of having one bulb per block, sitting high above the road, you’ve got … maybe 10? Which means that you have just that much more effort required to keep them all lit.
Once upon a time, I would periodically drive down Maple and count the number of acorns that were out, then blog about it. The Town seemed to take note, and get those replaced. (I think that’s up to Dominion Energy). I believe at one point, 21 out of 150 were burnt out.
More recently, I’ve purposefully stopped doing that. In my opinion, the quality of the lighting along Maple goes up every time one of those acorns burns out.
Four: Architecturally jarring and increasingly irrelevant. That’s the point of the picture at the start of this post.
Those acorns were installed in the 1990s, along with brick sidewalks, to try to give downtown Vienna a unified, old-town feel. I think they work well along Church Street, which has a genuinely small-town/old-town feel. They work well in other nearby towns and cities where the streetscape is appropriate. For example, the seem to fit in nicely in old town Manassas, below.
But on Vienna’s Maple Avenue, I don’t think they ever fit in. Maple Avenue is a hodgepodge of (mostly) 60’s and 70’s commercial suburban architecture, along five-lane arterial highway (Virginia Route 123). In that context, the lights were, at best, irrelevant to the look of the street. Sort of sad, really, but as long as the Town enforced the rule that all the big new buildings had brick facades, the fake olde-tyme lampposts and light globes more-or-less got lost in the background.
But now, the Town is all in on big, totally modern, glass-and-steel facade for the new library. That building facade is going to take up about half a block. And sitting in front of out will be the same fake olde-tyme acorn lights that populate the rest of the street.
In that context, you can still try to pretend that those olde-tyme lights are some sort of unifying factor for the streetscape. But they’re not. They’re just going to look silly. They become the Town’s equivalent of a lawn jockey (absent the racism). A piece of curbside kitsch, trying but failing miserably to evoke an earlier era.
Five: Town staff have already been directed to look for an alternative. You can see that documented in Post #580, in the context of the new Sunrise assisted living facility on Liberty Lane.
