Before Sterling Bay can break ground on its $5 billion to $6 billion vision for the vacant land between North and Webster avenues, the developer also will need to allay concerns about the project’s impact on nearby businesses, schools, public transportation, roads and bridges. Other remaining points of potential conflict include: the amount of park space Sterling Bay will provide on the site; heights of the tallest buildings, which could rise more than 50 stories; and the proposed use of public funds to create new infrastructure in an already traffic-choked area of the city.