I'm not that guy, and I'm all for rail, but here's an article that talks about it. https://seattletransitblog.com/2009/10/26/the-highway-vs-fixed-transit-debate/

"While a few rail-transit lines may have had a marginal effect on rush-hour congestion, the cost is exorbitant. The average light-rail line under construction or in planning stages today costs $25 million per mile ($50 million per mile in both directions). Heavy rail costs more than twice as much.  By comparison, the average lane mile of freeway costs only about $5 to $10 million."