Rail Transit consulting

There are a lot of rail transit commuter projects that have lost and continue to loose hundreds of millions of dollars in delays, faulty equipment, poor design, rail car builders being overwhelmed and mis management etc, all the while there are high priced consulting groups involved on every side of the project. What value do these consulting groups bring to the table with the money involved? Where do the interests of the public stand when public rail authorities hire high paid groups to push their cause and whose watching the hen house while there are few if any milestones to be met in consulting?