The car ferries that cross the Mekong at Neak Leung are an essential part of Cambodia's transport infrastructure. The current vessels were purchased in 1997, as part of a $20 million USD grant from the Mekong River Commission to upgrade ferry facilities in Cambodia. Despite the upgrade, there are sometimes significant delays while waiting to cross. If one of the ferries is not operational or traffic is particularly heavy, there may be queues of hundreds of vehicles and a wait of several hours to cross the river.