Due to dynamic pricing models, prices for the same route may vary based on the supply and demand for rides at the time the ride is requested. When rides are in high demand in a certain area and there are not enough drivers in such area, fares increase to get more drivers to that area. In some cases, this resulted in extreme surcharges during emergencies such as Hurricane Sandy, the 2014 Sydney hostage crisis, and the 2017 London Bridge attack.