This week, while Donald Trump ensnares himself in the most serious threat to his presidency to date, Congress is, to some extent, continuing with the typical business of government. A series of hearings during “Infrastructure Week†are focusing on the administration’s rumored infrastructure plan.Although the White House has been talking up private infrastructure investment as a replacement for public funding, a panel of experts told Congress that, even with perfectly executed public-private partnerships, the federal government still needs to provide its own support — especially for projects, like transit lines, that aren’t guaranteed to generate toll revenue for profit-seeking investors.This...