Ask Mr. Sun:

Why are the street lamps on Interstate 15 so tall?

Saturday, Aug. 29, 2009 | 2 a.m.

Ask Mr. Sun

Transportation officials say they use towering, “high-mast” lights because they are more efficient — nine or 10 times more by one measure.

The higher the light, the greater the surface illuminated below. Raising it to 100 feet — 60 to 70 feet higher than the standard streetlight — and placing it in the freeway’s center divider instead of along each shoulder, allow one high-mast light to do the work of nine or 10 shorter light poles.

Officials note that fewer lights translates into lower maintenance costs. And in case you were wondering, the high-mast lights are lowered using a pulley system inside the pole and serviced at ground level.

There’s a “How many Department of Transportation workers does it take to change a light bulb” joke here, but Mr. Sun will restrain himself.

Questions for Mr. Sun can be sent to page8@lasvegassun.com.

Discussion: 7 comments so far…

By drillmaker

9/1/09 at 12:44 p.m.

Suggest removal

I would say 8
1 field supervisor,1 department foreman, 1 pulley operator,2 to remove and replace the bulb, 2 to watch the progress and a flag person for traffic control.
By alexanderh

9/1/09 at 1:09 p.m.

Suggest removal

Your article didn't mention the obvious -- the further from the light source you get less brightness/illumination. To make up for it you have to use more powerful lights, more energy etc. [=more light pollution, but in Vegas that's just a drop in the bucket].

Even though you use less light bulbs & poles... "more efficient -- nine or 10 times more by one measure" -- what measure? It's hard to imagine such a magical 10 fold improvement.
By shtstirrer

9/2/09 at 1:51 p.m.

Suggest removal

i have to agree with alexanderh

the amount of electromagnetic radiation (light) received from a source decreases inversely as the distance from the source - squared (i.e. E ~ 1/r^2)

in plain english this means that at any given point you might get x watts, but at twice the distance from the same source, the amount of energy received is a QUARTER, or x/4 watts

so to get the same level of illumination as a conventional street lamp, you need a more powerful light source for a taller lamp like that found on I-15

the notion of efficiency is ambiguous and misleading. there are a number of ways of measuring efficiency. cost of materials used to construct a network of lamps, cost of maintenance, cost of running the lamps, etc. etc.
By dodgerchuck

9/3/09 at 10:33 p.m.

Suggest removal

the lite bulb has 2 want 2 change
By rejco100

9/4/09 at 4:14 p.m.

Suggest removal

The alien's motherships are HUGE!
By Doc_Holliday

9/5/09 at 10:08 a.m.

Suggest removal

Now we have people whining about light pollution...in Vegas of all places. MOVE AWAY TOOLS!!
By TheU

9/7/09 at 2:13 p.m.

Suggest removal

And the award goes to................. dodgerchuck