Route disable control and Aspect disable control/ Link

[PJW]

Hi PJW,

Could you tell me about " Route disable control and Aspect disable control/ Link ".

The attachment here has a couple of examples.

The first diagram shows the GY link in E10000 interlocking which is in the HR circuit for a given signal. When the GY link for a given route is slipped, even if the route is set, the signal will not clear.

The second diagram is the same sort of thing for BR free wired interlocking - the link to the left marked with the + does as the GY link does - preventing the GR from picking.

Both of these are physical links that are used to prevent the relevant circuit from operating. In RRI, stoppping a signal clearing for all routes is often does by removing the conenction to the control relay where there is a common relay for all routes (HR in E10k),

In SSI, the control is applied via the technician's terminal. The third block in the attachment show the range of technician's controls that are available and the final one shows a control being applied to bar a given route. This will stop the route being set, rather than as above, stopping the aspect clearing when the route is set. SSI does let you disconnect an aspect (option on the menu for aspect disconnect) as well and this will affect the aspect for all routes from that signal.

Let me know if that is the sort of thing you were looking for.

Peter

Perhaps the confusing thing is that the "route disconnection links" in standard free wired RRI circuits actually disconnects the ASPECT level for that particular route, whereas in SSI the route disconnection prevents the setting of the ROUTE and the "aspect disconnection" prevents a proceed aspect being displayed for any route.

There is also a "temporary approach contol facility" and in SSI this applies to all routes; normally this is not a problem as there is generally only one route which is not itself approach released anyway. However where this is MAY-FA for example, it would actually be beneficial to be able to impose separately for each individual route- whereas can do this in RRI, in SSI you can't. Therefore if imposing TACL because of some temporary speed restriction then sometimes have to make overly restrictive; the issue doesn't often arise but a right nuisance when it does, especially on a line fitted with ATP!