Pole Base Style

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WAbrothers

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Hello I am new to this forum,

Please forgive me if I'm asking the question in the wrong area.

Today while driving down the street I noticed that light poles are mounted to footings that sit flush with the street.
As I pulled into the parking lot I noticed that poles sit on bases about 3 feet above the ground.

Whats the difference between the two?
When do you chose one over the other?

Thanks,

Wojtek
 
WAbrothers said:
Hello I am new to this forum,

Please forgive me if I'm asking the question in the wrong area.

Today while driving down the street I noticed that light poles are mounted to footings that sit flush with the street.
As I pulled into the parking lot I noticed that poles sit on bases about 3 feet above the ground.

Whats the difference between the two?
When do you chose one over the other?

Thanks,

Wojtek
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Flush with the STREET or flush with the SIDEWALK or ground? I doubt you saw light poles in/on the street itself.

And that's usually the issue. In a parking lot, there are normally cars in the area, so inattentive drivers will hit poles that are flush to the driving surface. You therefore mount those on pedestals that, if the drivers hit them, damage the car, not the pole (potentially exposing the wires and risking contact). Streetlight poles are typically on or past the sidewalk or median strip where they are only at risk to contact from cars if there is some sort of severe accident.

Welcome to the forum by the way!
 
What matters is how much foundation or pole (if direct burial) is in the ground. An engineer calculates a tipping moment and makes sure the pole is not going to fall over from wind and other forces, but hopes it does shear off and fall over if hit by a car, to lessen injuries to the occupants of the car.

Welcome to the forum.
 
Jraef said:
Flush with the STREET or flush with the SIDEWALK or ground? I doubt you saw light poles in/on the street itself.

And that's usually the issue. In a parking lot, there are normally cars in the area, so inattentive drivers will hit poles that are flush to the driving surface. You therefore mount those on pedestals that, if the drivers hit them, damage the car, not the pole (potentially exposing the wires and risking contact). Streetlight poles are typically on or past the sidewalk or median strip where they are only at risk to contact from cars if there is some sort of severe accident.

Welcome to the forum by the way!
Click to expand...

You're right they are up on the curb and not at the road level.


Thanks for the reply!
 
WAbrothers said:
Today while driving down the street I noticed that light poles are mounted to footings that sit flush with the street.
As I pulled into the parking lot I noticed that poles sit on bases about 3 feet above the ground.

Whats the difference between the two?
When do you chose one over the other?
Click to expand...

For us we will place the base more or less flush with grade for light poles that are otherwise protected from vehicles by curbs, barriers or distance.

For poles in open parking lots we go 36" above grade with the base to protect the poles from vehicles.
 
While is is often common to see the top of the pole bases very close to flush with the surface where they are on sidewalks or behind the curb in the landscaping, and on bases 2-3' above grade in parking lots, in areas where they use a lot of snow and ice melting salt, it is my opinion the ones in the sidewalk or in the landscaping areas also need to be on higher bases to protect from the salt. I have replaced a number that failed do to salt corrosion where they had been placed with a flush base and near areas that are salted to remove ice and snow.
 
don_resqcapt19 said:
While is is often common to see the top of the pole bases very close to flush with the surface where they are on sidewalks or behind the curb in the landscaping, and on bases 2-3' above grade in parking lots, in areas where they use a lot of snow and ice melting salt, it is my opinion the ones in the sidewalk or in the landscaping areas also need to be on higher bases to protect from the salt. I have replaced a number that failed do to salt corrosion where they had been placed with a flush base and near areas that are salted to remove ice and snow.
Click to expand...

Another consideration that trumps salt corrosion in my opinion is the ability to break away. A curb doesn't really protect the pole from street traffic, however, since the person in the vehicle is more important than the pole, (well usually:D) you want a pole that will break before it breaks the car.
 
Another way to look at it is that collisions with parking lot poles will (we hope) be low speed while collisions with roadway poles may be high speed. In most states road poles and signs have a designed breakaway weak point just above ground level. It does not affect strength against tipping but will separate on horizontal force.
 
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