Thread Rating:
  • 1 Vote(s) - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Temporary Approach Control
#1
Hi, Kindly explain me about Temporary Approach Control and in which cases it can be used.
Reply
#2
(05-09-2009, 01:49 PM)Ragavendiran Wrote: Hi, Kindly explain me about Temporary Approach Control and in which cases it can be used.

It is actually a facility that in my experience is hardly ever used, but is usually provided "just in case". It is provided on all main running signals except when they are always MAR (since if they are always approach released anyway there is no value).
It imposes approach release (i.e signal held at red until berth track occupied) but only when invoked by technician (slip a link in RRI, via technician terminal instruction for SSI etc).
In theory it would be used when a new works commissioning is running late and it is essential to open the railway again, albeit in degraded mode- the speed of traffic is limited as trains always expecting to stop at signal but then they get proceed before they have actually stopped. More useful in RRI (where aspect sequence was always the last thing to be tested) than SSI (when is largely tested "off-site" many months before- except at fringes).

Occasionally might be used to protect incidents or severe emergency speed restrictions- but again this probably was invoked more in times past than current day. I think that we wouldn't continue to provide the facility if it were not inherently built into SSI and thus all but "comes for free".
PJW
Reply
#3
Hi Mr.PJW,

Thank you for your quick response.
Reply
#4
(05-09-2009, 04:45 PM)PJW Wrote: Occasionally might be used to protect incidents or severe emergency speed restrictions- but again this probably was invoked more in times past than current day.  I think that we wouldn't continue to provide the facility if it were not inherently built into SSI and thus all but "comes for free".

We use it in complex areas if there is a speed restriction and multiple routes up to it which would mean a huge number of ATP routes needing speed restriction chips.
Reply
#5
We found some latent wrong side errors when doing a re - lock earlier this year. The immediate mitigation was to apply the Temporary Approach Control to the affected signal pending updated interlocking data.
Not the use envisaged, but a safety - related use of the function.
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)