The House T&I Committee published their draft of the renewal of the FAST Act. Section 4405 addresses Truck Underride: Underride Section of FAST Act 2020 – INVEST in America
You can compare it to the STOP Underrides Bill: Text – H.R.1511 – 116th Congress (2019-2020)_ Stop Underrides Act _ Congress.gov _ Library of Congress
Update (September 13): Comparison Chart of Underride Provisions in Various Bills
And here are the GAO Underride Recommendations: GAO Truck Underride Recommendations