runs from October through September.) This has been coupled with a steady rise in average ship size and in the numbers of Panamax vessels passing through the canal, so that the total tonnage carried rose from 227.9 million PC/UMS tons in fiscal year 1999 to a then record high of 312.9 million tons in 2007, and falling to 299.1 million tons in 2009. Tonnage for fiscal 2013, 2014 and 2015 was 320.6, 326.8 and 340.8 million PC/UMS tons carried on 13,660, 13,481 and 13,874 transits respectively. In the first decade after the transfer to Panamanian control, the Panama Canal Authority (ACP) invested nearly US$1 billion in widening and modernizing the canal, with the aim of increasing capacity by 20 percent. The ACP cites a number of major improvements, including the widening and straightening of the Culebra Cut to reduce restrictions on passing vessels, the deepening of the navigational channel in Gatun Lake to reduce draft restrictions and improve water supply, and the deepening of the Atlantic and Pacific entrances to the canal. This is supported by new equipment, such as a new drill barge and suction dredger, and an increase of the tug boat fleet by 20 percent. In addition, improvements have been made to the canal's operating machinery, including an increased and improved tug locomotive fleet, the replacement of more than of locomotive track, and new lock machinery controls. Improvements have been made to the traffic management system to allow more efficient control over ships in the canal. In December 2010, record-breaking rains caused a 17-hour closure of the canal; this was the first closure since the United States invasion of Panama in 1989. The rains also caused an access road to the Centenario Bridge to collapse. Capacity The canal handles more vessel traffic than had ever been envisioned by its builders. In 1934 it was estimated that the maximum capacity of the canal would be around 80 million tons per year; as noted above, canal traffic in 2015 reached 340.8 million tons of shipping. To improve capacity, a number of improvements have been made to maximize the use of the locking system: Implementation of an enhanced locks lighting system; Construction of two tie-up stations in Culebra Cut; Widening Culebra Cut from ; Improvements to the tugboat fleet; Implementation of the carousel lockage system in Gatun locks; Development of an improved vessel scheduling system; Deepening of Gatun Lake navigational