Elasticity of demand is employed to analyze the reaction degree of demand changing with its effect
factors, that is to say it is the ration between the percentages of demand changing to the percentage of
effect factors changing. There are many scholars implementing elastic analysis model into transportation
research field, such as Wang et al. (2004) studied the elastic relations between volume of traffic to
economic quantities. Tian et al (2009) analyzed the demand elasticity of railway transportation capacity
and GDP. Lane (2011) employed elastic analysis method to discuss the relationship between oil prices
and public transport, and the results showed that traffic volume of bus and rail transit increases 4% and
8%, respectively when the oil price rise 10%. Litman (2011) put forward the price elasticity of public
transport and elastic demand value for public transportation planning from the view of trip distance, trip
purpose, travel time, etc. Elastic analysis method is employed to discuss the effect of PTP, especially low-
price strategy.