Rapid transitRapid transit or mass rapid transit (MRT), also known as heavy rail or metro, is a type of high-capacity public transport that is generally built in urban areas. A rapid transit system that primarily or traditionally runs below the surface may be called a subway, tube, or underground. Unlike buses or trams, rapid transit systems are railways, usually electric, that operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles. They are often grade-separated in tunnels or on elevated railways.
Cost overrunA cost overrun, also known as a cost increase or budget overrun, involves unexpected incurred costs. When these costs are in excess of budgeted amounts due to a value engineering underestimation of the actual cost during budgeting, they are known by these terms. Cost overruns are common in infrastructure, building, and technology projects. For IT projects, a 2004 industry study by the Standish Group found an average cost overrun of 43 percent; 71 percent of projects came in over budget, exceeded time estimates, and had estimated too narrow a scope; and total waste was estimated at $55 billion per year in the US alone.
