Whenever someone suggests building more roading capacity to solve congestion I just link them to “The Fundamental Law of Road Congestion” https://www.aeaweb.org/articles?id=10.1257/aer.101.6.2616

This is just basic economics. Increasing supply reduces the cost and therefore demand rises to meet the new level of supply. Why the right wing preaches economic purism on everything but transport boggles my mind.