Dark Arch

The Arch has been dark this week in the evenings, and I could not remember why exactly, but knew that it had something to do with a migration of some creature. It turns out to be birds!

FYI from the Head Arch Dude:

Thank you for interest on lighting the Gateway Arch at night.

We are open to the public from 8am to 10 pm during the period of Memorial
Day through Labor Day. If the lights are turned on any earlier than 10 pm,
it would shine directly into the eyes of visitors at the top of the Arch
making it impossible to see or look out from the Arch observation deck.

As you may know, low clouds that hide the night sky that birds use to
navigate by, combined with artificial light, result in a halo effect that
can cause birds to fatally fly into artificially lit structures.
Therefore, for two weeks in the spring and again for two weeks in the fall,
the Arch is not lit due to spring and fall bird migrations.

Also, times of low cloud cover, during rain, or snow storms has effect on
the aesthetics of the lighting causing the 44 light beams themselves
becoming the focal point as opposed to the object beging lit. Hence, you
have 44 beams illuminating nothing which is an obvious distraction from the
Arch itself. To avoid illuminating nothing, a ceilometer automatically
shuts the lights off when such events occur, and conversely, turns them on
again when the situation changes. Otherwise, here is the Gateway Arch
Exterior Lighting schedule:

Oct through March 6pm - 12midnight
April through May 7pm - 12 midnight

May (beginning Memorial Day weekend) through September 10pm - 1am
September (beginning the day after labor Day) 6pm -
12midnight

And, if that is not sufficiently complicated, keep in mind that we permit
after hours events to be held during the evenings between Labor Day and
Memorial Day. Should a permitee request that the tram ride to the top of
the Arch be available, we cannot turn on the exterior lights until their
event has concluded which sometimes can be as late as midnight.

We do hope this sheds some light on the Arch and as always we appreciate
your interest.

Sincerely,

/s/Franklin D. Mares
Deputy Superintendent