H-20 Load Ratings Explained

There is often confusion when simply referring to H-20 Load Rating—does it mean 16,000 lbs, 20,000 lbs, or 40,000 lbs?

Load Testing Setup
Load Testing Setup

Let's clarify: H-20 loading refers to a two-axle truck with design criteria of truck axle loading of 32,000 lbs, or 16,000 lbs per wheel load.

On the other hand, the American Association of State Highway Transportation Officials (AASHTO) established performance criteria for the manufacturing of gray iron castings subject to heavy traffic, commonly known as H-20 or HS-20 loading.

HS-20 specifically refers to a truck with more than 2 axles.

Now, we can confidently say that Bingham & Taylor plastic meter lids and meter pits meet the H-20 load rating of 16,000 lbs, providing reliability and durability in heavy traffic conditions.

What is the AASHTO M 306 Standard?

lid not properly tested
Lid Not Properly Tested Load Transferred to Frame

The AASHTO M-306 Standard applies to gray cast iron frames and covers that may be placed in traffic service and load bearing is a consideration.

It requires a safety factor of 2.5 x the H-20 loading, which equates to a 40,000 lb proof load (2.5 x 16,000 lbs).

AASHTO M 306 Testing Specifications

Although H-20 and AASHTO M-306 specifically apply to metal castings, many in the waterworks industry have used these designations and specifications when describing plastic or composite meter lids and meter pits.

Here are some key testing parameters according to AASHTO M-306:

  • The proof load shall be applied evenly over a 9”x9” square area at the center of the lid. For items where a 9”x9” footprint would transfer the load directly to the frame, the loading footprint size shall be smaller than the corresponding frame clear opening.
  • The loading footprint size shall not exceed 9” in any direction.
lid properly tested
Lid Properly Tested Load Fully on Lid

B&T Plastic Meter Lids and Meter Pits

To avoid any confusion and provide complete transparency, Bingham & Taylor always goes the extra mile to specify the proof load under which our products are tested.

When it comes to our plastic meter lids and meter pits, they are designed to meet a robust proof load of 20,000 lbs. Not only that, but they undergo rigorous testing, adhering to the key parameters of AASHTO M-306.

Our meticulous testing process ensures that the loading does not directly transfer to the frame, guaranteeing the utmost durability and reliability.

To carry out these tests effectively, B&T employs a specially-designed 9” diameter steel plate. This ensures that the lid is properly tested and can withstand real-world conditions.

We leave no stone unturned in ensuring the highest quality and performance of our products.

Lastly, it is important to note that our plastic meter lids and meter pits are not intended for installation in roadway areas. Their purpose is to provide exceptional functionality and safety in non-roadway applications where they truly shine.