dimensions of ships using these locks increased by 25 percent in length, 51 percent in beam, and 26 percent in draft, as defined by New Panamax metrics. Tolls As with a toll road, vessels transiting the canal must pay tolls. Tolls for the canal are set by the Panama Canal Authority and are based on vessel type, size, and the type of cargo. For container ships, the toll is assessed on the ship's capacity expressed in twenty-foot equivalent units (TEUs), one TEU being the size of a standard intermodal shipping container. Effective April 1, 2016, this toll went from US$74 per loaded container to $60 per TEU capacity plus $30 per loaded container for a potential $90 per TEU when the ship is full. A Panamax container ship may carry up to . The toll is calculated differently for passenger ships and for container ships carrying no cargo ("in ballast"). , the ballast rate is US$60, down from US$65.60 per TEU. Passenger vessels in excess of 30,000 tons (PC/UMS) pay a rate based on the number of berths, that is, the number of passengers that can be accommodated in permanent beds. The per-berth charge since April 1, 2016 is $111 for unoccupied berths and $138 for occupied berths in the Panamax locks. Started in 2007, this fee has greatly increased the tolls for such ships. Passenger vessels of less than 30,000 tons or less than 33 tons per passenger are charged according to the same per-ton schedule as are freighters. Almost all major cruise ships have more than 33 tons per passenger; the rule of thumb for cruise line comfort is generally given as a minimum of 40 tons per passenger. Most other types of vessel pay a toll per PC/UMS net ton, in which one "ton" is actually a volume of . (The calculation of tonnage for commercial vessels is quite complex.) , this toll is US$5.25 per ton for the first 10,000 tons, US$5.14 per ton for the next 10,000 tons, and US$5.06 per ton thereafter. As with container ships, reduced tolls are charged for freight ships "in ballast", $4.19, $4.12, $4.05 respectively. On 1 April 2016, a more complicated toll system was introduced, having the neopanamax locks at a higher rate in some cases, natural gas transport as a new separate category and other changes. As of October 1, 2017, there are modified tolls and categories of