US SB3636

Extends and modifies the TIFIA (Transportation Infrastructure Finance and Innovation) program through fiscal years 2027-2031, expanding eligibility for transit-oriented development projects located within ½ mile of transit stations that include housing, commercial, or mixed-use components

Creates a new "attainable housing project" category for developments serving households at or below 120% of area median income, with reduced interest rates at half the Treasury Rate and requirements that 75% of financial assistance go toward residential components

Establishes delegated origination and underwriting programs for both TIFIA and the Railroad Rehabilitation and Improvement Financing (RRIF) program, modeled on HUD's Multifamily Accelerated Processing system to streamline loan approvals

Provides alternatives to investment-grade credit ratings for transit-oriented development projects, including joint liability agreements with government entities or alternative creditworthiness assessments for loans of $150 million or less

Expands NEPA categorical exclusions for transit-oriented development projects, including office-to-residential conversions and construction on previously disturbed transportation land, while preserving state and local zoning authority