New Delhi, Dec. 22 -- In the early hours of December 16, a multi-vehicle pileup on the Yamuna Expressway in Mathura caused by fog-induced low visibility killed at least 13 people as a result of the fire caused by the successive crashes. While the crash involved three cars and seven buses, six of which were sleeper coaches, a factor that rescuers later said made evacuation more difficult was that passengers were trapped inside narrow berths amid smoke and fire. Less than two months ago, on October 24, another sleeper bus caught fire in Andhra Pradesh's Kurnool district after it was hit by a motorcycle from behind, killing 20. Ten days before, a private AC sleeper bus travelling from Jaisalmer to Jodhpur went up in flames, killing 26 as fire ...