What caused the eight-hour traffic jams?

Thousands of commuters are facing eight-hour traffic jams while crossing a 16-mile causeway linking Saudi Arabia to the island of Bahrain.
    Queues last well into the night, and officials admit there’s no end in sight, the Arab News reports. When Saudi authorities investigated, they found there are not enough customs officials on the border to cope with the tens of thousands of people trying to cross every day—but this has led to a falling-out between the Traffic Department and the Passport Department, which blame each other for the gridlock.
    Saudi traffic police say they do their best to keep the queues moving, issuing around 90 fines every day, including 20 for parking violations. Police also say they are making daily arrests of illegal taxi drivers transporting people between the two countries.