I love the question as this trade agreement is critical for the railroads.
First, just having an agreement in place is vital to rail as more than 40% of trade goods in North America move by rail. I believe I read an article that said trade between the US, Canada, & Mexico has quadrupled over the past 25 years. We are talking almost $1.5 Trillion dollars of trade and the railroads handle 40%.
Personally, I am a data geek so my favorite part is the modernizing of the trade agreement to account for e-commerce, digital trade, & a commitment to open flows of data. These changes will preserve and increase rail traffic plus more data helps everyone.