to emphasize on this one, each of our lines, because they operate both on the subway and on the servicsurface, if you haa delay in 19 will affect the other ones. the guys we operate in street traffic and a subject to stop signs and those sorts of things, we are vulnerable to having delayed it generated in the subway as well as on the streets. we have a heavily utilized, you need, and complex system. in terms of what kinds of problems, you may remember a couple of months ago there was a series of lengthy delays. they resulted in a number of people being inconvenienced, sometimes for several hours. on this slide is a brief description of the major causes of those delays called switch problems, a problem with a mechanical attachment which is on the undercarriage of the car which cuts the signal cable in the subway, as well as one of the challenges when your operating in manual, when you get to one of the port is to receive automatic train control. our system is designed to run on automatic control and the reliability of the system is much higher when it is an automatic control as opposed to a ma