In "The Oxford Olympics Study 2016: Cost and Cost Overrun at the Games," three researchers from the University of Oxford's Said Business School examine the cost estimates and actual costs of every Olympic games since 1960, and finds that they are the most likely of all megaprojects to exceed their estimates, and also exceed those estimates by the largest amount of any megaproject.
Main findings of the study are, first, that average actual out turn cost for Summer Games is USD 5.2 billion (2015 level), and USD 3.1 billion for Winter Games. The most costly Summer Games to date are London 2012 at USD 15 billion; the most costly Winter Games Sochi 2014 at USD 21.9 billion. The numbers cover the period 1960-2016 and include only sports-related costs, i.e., wider capital costs for general infrastructure, which are often larger than sports-related costs, have been excluded.
Second, at 156 percent in real terms, the Olympics have the highest average cost overrun of any type of mega-project. Moreover, cost overrun is found in all Games, without exception; for no other type of mega-project is this the case. 47 percent of Games have cost overruns above 100 percent. The largest cost overrun for Summer Games was found for Montreal 1976 at 720 percent, followed by Barcelona 1992 at 266 percent. For Winter Games the largest cost overrun was 324 percent for Lake Placid 1980, followed by Sochi 2014 at 289 percent.
[Bent Flyvbjerg, Alexander Budzier and Allison Stewart/University of Oxford Said Business School]