I noticed these "beak" like objects above traffic lights and was
wondering what purpose these serve.  For a photo, please see: 
http://pg.photos.yahoo.com/ph/chelatingblues/

Does anyone know?

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Clarification of Question by nowaytia-ga on 16 Jan 2006 19:55 PST

Myoarin - that sounds like the right answer to me.  If you find out
whether they operate using infrared or radio, please let me know.  (I
can't believe you can jam them...!)

I'm not sure why the photo is not showing up for you.  I reloaded a
smaller version of the photo.....

http://pg.photos.yahoo.com/ph/chelatingblues/album?.dir=/ed22&.src=ph&.tok=ph1.wQEBo0Nf2XUV

....perhaps that will help.  The "beaks" ("periscopes") are frequently
on the main roads for a town and look fairly new.

Thanks!

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Request for Question Clarification by tutuzdad-ga on 09 Feb 2006 14:23 PST

Contrary to what has been suggested below, Traffic Signal Preemption
Systems (as they are called in the biz) most often utilize infrared
and do not require any type of "receiver" positioned directly over the
light itself, rather these are commonly on a nearby pole or cross
beam. The "beak", as you described it, most likley serves merely as a
visor to increase light visibility and color discernability in adverse
conditions (sunshine, rain, fog, etc).

Here is a high resolution photo of a traffic light ensemble complete
with visors (over the lenses of the light) and preemptive device (on
the cross beam on the left).

http://www.chardonfire.com/Picture_2482.JPG

Does this answer your question?

tutuzdad-ga

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Request for Question Clarification by tutuzdad-ga on 09 Feb 2006 14:28 PST

You can read more about these systems here and see exactly how the
"emitter" is positioned. These leave little doubt that the visor you
are talking about is NOT an preemptive device:

WATTCO
http://www.wattco.net/opticomemitters.htm

http://www.wattco.net/infopdf/opti1.pdf

http://www.wattco.net/infopdf/opti2.pdf

http://www.wattco.net/infopdf/Transit%20Applications%20Brochure%20-%2075-0500-3577-5.pdf

Let me know.

tutuzdad-ga

Some places there are traffic lights that turn red four ways when
emergency vehicles approach.  I expect this beak could be a receiver
for a radio or other signal transmitted by the vehicles when they have
the right of way.

Yes, here is a site mentioning electronic controls, and the second one
mentions infra-red, which looks like what this beak would be
receiving:


http://www.nasatech.com/Briefs/May05/NPO40492.html

http://64.233.183.104/search?q=cache:MQlDOouXGRsJ:www.themirt.com/+traffic+lights+emergency+vehicles&hl=en

Sorry, the straight link with photos did not come up.

myoarin is right it is for the receiver to be housed so they can pick
up the signals.

Is there public transportation service (i.e., bus) on the road with
this beak?  I have heard that some busses have emitters that tell the
traffic signal "I'm coming" so that the signal can prioritize to let
the bus through expeditiously.

J.

The "beak" is not meant for recievers of any signals. It is basically
meant to provide greater visibility during sunshine. Also, when there
are a group of lights, it is meant to make sure that the traffic from
each direction see only the lights meant for them (and not the other
ones and get confused).

Also, it is true that traffic lights have recievers that can turn them
green or red for an oncoming emergency vehicle. This can be done
either through the loud bell or the rotating lights (depending on the
what kind of sensor is used). But these sensors are placed outside the
"beak" in most cases.

THANK YOU for the Wattco information.  That is exactly what I was looking for.

I have noticed that - at least around Chicago - the thing on top of
the pole also has a small light that flashes white when the emergency
vehicle comes thru. Kind of a nice warning as to why all the lights
suddenly went red.