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Determining Proper ANSI Load Ratings for Underground Pull Boxes

Determining the proper load ratings for underground pull boxes is critical to ensuring public safety. The following article is designed to help you understand what factors to consider in choosing the proper traffic rating for pull boxes and covers.  Should you have any questions, please call our experts at 800-767-1576, contact us  or view traffic rated pull box products for information on each specific enclosure. 
 

Traffic Type

ANSI 77 sets forth 6 types of traffic for load ratings. Consider each of these when determining which tier rating is needed for your project. Information on ANSI 77 Testing Requirements can be found at the end of this article.

Light Duty: Pedestrian traffic only.
Example: grassy areas in residential properties that are located away from vehicular traffic.

TIER 5: Sidewalk applications with a safety factor for occasional non-deliberate vehicular traffic.
Example: Residential sidewalk that is not crossed by a driveway. 

TIER 8: Sidewalk applications with a safety factor for non-deliberate vehicular traffic.
Example: Most public sidewalks
Example: Within parking curbs of parking lots where it is highly unlikely to be run over. 

TIER 15: Driveway, parking lot, and off-roadway applications subject to occasional non-deliberate heavy vehicular traffic.
Example: Sidewalks in residential or public areas where heavy vehicle traffic is unlikely, but may occur.

TIER 22: Driveway, parking lot, and off-roadway applications subject to occasional non-deliberate heavy vehicular traffic. 
Example: Non-paved median between a divided highway or non-paved shoulder area. 

AASHTO H-20: Deliberate vehicular traffic applications. 
Example: Within streets, highways and paved shoulders along highways. 

 

ANSI 77 Testing Requirements

Testing requirements have been developed by the Society of Cable Telecommunications Engineers, and are contained in their document: ANSI/SCTE 77 Specification for Underground Enclosure Integrity. View document
 
  1. Environmental Tests: Chemical Resistance, Sun Exposure, Water Absorption & Flammability 
     
  2. Structural Tests: Three position testing of Lateral Sidewall Pressure, Vertical Sidewall Load, Cover Vertical Load
     

Table of ANSI  77 Design/Test Loads

Application Loading Requirements
Light Duty Vertical Test Load 13.3kN 3000 pounds
TIER 5

Vertical

 

Lateral

Design Load

Test Load

Design Load

Test Load

22.2 kN 

33.3 kN 

28.7 kPa 

43.1 kPa

5000 pounds

7500 pounds

600 pounds/sq.ft.

900 pounds/sq.ft. (1800/2700 pounds/ lateral load plate)

TIER 8

Vertical

 

Lateral

Design Load

Test Load

Design Load

Test Load

35.6 kN 

53.4 kN 

28.7 kPa 

43.1 kPa

8000 pounds 
 
12000 pounds
 
 600 pounds/sq.ft. 
 
900 pounds/sq.ft. (1800/2700 pounds/ lateral load plate)
TIER 15

Vertical

 

Lateral

Design Load

Test Load

Design Load

Test Load

66.7 kN 
 
100.1 kN 
 
38.3 kPa 
 
57.5 kPa
15000 pounds 
 
22500 pounds 
 
800 pounds/sq.ft.
 
1200 pounds/sq.ft. (2400/3600 pounds/ lateral load plate)
TIER 22

Vertical

 

Lateral

Design Load

Test Load

Design Load

Test Load

100.1 kN 
 
150.1 kN 
 
38.3 kPa
 
57.5 kPa
22500 pounds 
 
33750 pounds
 
 800 pounds/sq.ft.
 
1200 pounds/sq.ft. (2400/3600 pounds/ lateral load plate)
AASHTO H-20
Certified precast concrete, cast iron, or AASHTO recognized materials. Polymer composite test provisions do not exist and are not recognized by AASHTO.
 

 

  1. Coefficient of Friction Testing for slip resistance (covers) of minimum of 0.50 as determined by ASTM 1028-06 Section 8.
     
  2. Torque Value of Fastening Devices.
     

Other Articles You May Enjoy:

Choosing the Right Underground Enclosures

How to Calculate Underground Pull Box Sizing

 

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