GO Expansion, previously known as GO Regional Express Rail (RER), is a project to improve GO Transit train service by adding all-day, two-way service to the inner portions of the Barrie line, Kitchener line and the Stouffville line, and by increasing frequency of train service on various lines to every 15 minutes or better on five of the corridors. This would be achieved with the electrification of at least part of the Lakeshore East line, Lakeshore West line, Barrie line, Kitchener line and Stouffville line. GO Expansion is one of the Big Move rapid transit projects.