Traffic jams can happen inside buses, too. They're caused by those clueless riders who, upon entering and paying the fare, stay as close as possible to the front of the bus. Those boarding after cram into this human congestion, which can quickly become intractable as more and more people get on board and stay at the front. An available seat, or at least breathable space, is often within eyesight, mere feet away at the back of the bus.
Now, this can be unpleasant due to the many bodily odors and general sweatiness of bus riders in tight quarters. It can also really slow things down. Getting people from the bus stop and into the bus is a time-consuming process. San Francisco's Municipal Transportation Agency, Muni, is hoping to speed up that process and cut down that frustrating front-of-the-bus body crush by doing what no other transit agency in the U.S. has done. Beginning July 1, Muni started allowing its riders to board the bus from the back door as well as the front.