What is T-1 steel and should the Tri-State be concerned?

HENDERSON, Ky. (WEHT) – The Twin Bridges are confirmed by the Kentucky Transportation Cabinet (KYTC) to be made from T-1 steel .

The technical name of this type of steel is AASHTO M244 Grade 100 steel, which is often shortened to T-1.

There are some concerns in regard to this type of steel.

Why is T-1 steel an issue?

According to the KYTC and INDOT, T-1 steel is a grade of high-strength quenched and treated steel known for being highly amenable to welding and machining. This steel is no longer used in bridge construction but was used in the 1950s and 1960s around the country.

INDOT says concerns related to T-1 steel surfaced in the 2000s, prompting specific inspection and mitigation requirements from the Federal Highway Administration (FHWA). KYTC says in May 2021, a fracture was discovered in a weld, referred to as a “butt weld,” in a T-1 steel component of the Interstate 40 Hernando de Soto Bridge between Memphis, Tennessee, and West Memphis, Arkansas. As a result, the FHWA in December 2021 issued a memorandum to states to identify and inspect specific T-1 steel bridges to verify the soundness of all butt welds with the use of non-destructive testing.

Who sets the standards?

There are two entities transportation officials mentioned that set standards when it comes to steel.

FWHA says the American Association of Highway and Transportation Officials (AASHTO) is a nonprofit association in charge of setting design and installation standards, providing guidance and resources and developing outreach materials. ASTM International says it offers global access to “fully transparent” standards development.

Tri-State transportation departments weigh in

Illinois

According to the Illinois Department of Transportation (IDOT), there are no impacts on T-1 steel on either the I-64 Bridge in Grayville or the Mt. Carmel Wabash River Bridge in Mt. Carmel, nor is either bridge made out of T-1 steel. However, outside the Tri-State area, there are three bridges in Illinois that contain T-1 steel.

IDOT says the three bridges in Illinois with T-1 steel are:

• I-270 over the Mississippi River, which is expected to be removed at the end of the year
  • This is near St. Louis, Missouri.
• I-24 bridge over the Ohio River
  • This is near Paducah, Kentucky and Metropolis, Illinois.
• I-55/64 bridge over the Mississippi River
  • This is near Cape Girardeau, Missouri.

Officials with IDOT say currently, there are no issues with T-1 steel bridges in Illinois, and all bridges have been inspected per the FHWA December 13, 2021 memorandum. These days, bridges are made out of AASHTO M270 Grade 50 steel.

Officials say the I-64 bridge in Grayville has ASTM A36 steel and ASTM A441 steel, and the Mt. Carmel bridge has AASHTO M270 Grade 50W and Grade HPS 70W steel.

This is what those types of steel are:

• M270
  • According to AASHTO , this is structural steel for bridges.
• A36
  • According to Leeco Steel , this steel is one of the most common grades of steel used in structural applications. It’s a mild carbon steel grade that contains chemical alloys that give it properties such as machinability, ductility and strength that are ideal for use in constructing a variety of structures.
• A441
  • According to the Massachusetts Institute of Technology , this is a high-strength low-alloy manganese-vanadium steel.

Kentucky

According to the KYTC, while the welds found in T-1 bridges posed no immediate safety issues, there are a few Kentucky bridges that contain T-1 steel components. In the Tri-State, this Kentucky bridge is the U.S. 41 southbound Ohio River bridge between Henderson and Evansville, known to most as just the Southbound Twin Bridge.

In terms of other areas in Kentucky, those bridges with T-1 components are:

• Two I-24 Tennessee River bridges connecting Marshall and Livingston counties.
• I-65 southbound John F. Kennedy Memorial Bridge over the Ohio River at Louisville.
• I-275 Carroll Lee Cropper Bridge over the Ohio River in Boone County.
• I-275 Combs-Hehl twin bridges over the Ohio River in Campbell County.

KYTC notes today’s high-strength steel used to build bridges must meet enhanced federal requirements and specifications. To further ensure safety, the KYTC inspects bridges at least once every two years and, in some cases, yearly, depending on age, condition and design.

Indiana

The Indiana Department of Transportation (INDOT) says it inspects and maintains more than 5,700 state bridges on its transportation network. Each structure is inspected at least once every two years to ensure safety.

INDOT says Indiana maintains three bridges that have T-1 steel in them:

1. I-64 over the Ohio River – Sherman Minton Bridge in New Albany, Indiana.
2. SR 237 over the Ohio River – Bob Cummings Lincoln Trail Bridge in Cannelton, known to some as either the Bob Cummings Bridge or the Lincoln Trail Bridge.
3. SR 135 over the Ohio River – Matthew E. Welsh Bridge in Mauckport, Indiana.

INDOT says all three have been inspected and any concerns mitigated per guidance from FHWA.

Officials say today, high-strength steel used in bridge construction must meet requirements of the AASHTO M270 or its equivalent, ASTM A709 specifications. These standards have led to improved material properties such as ductility, toughness and hardness.

According to Leeco Steel, ASTM A709 is a common steel plate grade used primarily for the manufacture of bridges.

Conclusion

Overall, there are two T-1 bridges in the Tri-State. One is the southbound Twin Bridge in Henderson, and the other is the Bob Cummings Bridge near Cannelton and Hawesville, and this bridge is sometimes referred to as the Lincoln Trail Bridge.

As both INDOT and KYTC say those bridges have been inspected, there is no cause for concern.

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