redesigned our switch maintenance program to focus on high usage switches, such as the church at dubose. with the help of the signal manufacturing company, we limited the number of trains. we also made repairs to the sanderhose where we changed our men's procedures and there has been no incidents since then. the point of all of this is we improved our reliability. as this chart indicates, as far as the total number of switchbacks, in september they were higher than they have since come down. the point we want to make here is the number of switchbacks is a service management technique that we use in the event of a delay in the system. in our discussions, you had had asked, could we break up the time of the switchbacks? over the last couple of months we have a layout from september to december of the time of day. supervisor chu: you are going pretty quickly. it in terms of the lrv switch back, you say that it is sometimes required to make sure the system goes back in place. could you explain that more? >> are we tag