The overcrowding on Bart as a result of the Bay Bridge closure this week reinforces the need for serious capacity improvements in the system. Capacity problems permeate nearly every aspect of Bart–station access, platform area, vehicle space, train operations, parking, etc.–but while Bart has focused a lot on system expansion in recent years, it simply hasn’t put in the effort to meet the current and future needs of the existing system. The overcrowding this week is not a freak occurrence; rather, it is a preview for what Bart will regularly face 10 years (or less?) down the road. Population growth, climate change, peak oil, and traffic congestion are not simply going to go away, and until Bart/MTC can find the $10 billion that it’s going to take to build a second tube (probably in the next 50 years), Bart needs to invest in ways to maximize the efficiency of its current system through better station design, vehicle layout, parking management, transit and bicycle access, and train control. We need to reinvest in Bart for a sustainable future.