As the ambitious plans to redevelop the West Side run into problems, some planners and officials are calling for changes to keep the area growing. Several planners say the expensive tree-lined boulevard planned for between 10th and 11th Avenues (from 33rd Street to 42nd Street) should be scrapped. Others want zoning loosened to allow residential towers to be built on 11th Avenue. Critics say the city was wrong to think that a new commercial district would quickly spring up around Hudson Yards, which lacks public transit, and that commercial development always moves block by block. They say public resources should be focused around Penn Station and its surrounding office district, which needs grants, tax credits and zoning changes to develop.