[alma-config]Reconfiguration Times

[John Conway]

On Mon, 15 Apr 2002, David Woody wrote:

> I caution against trying to be too detailed in the transporter
> and moving crew schedule.  You almost never gain the
> increase in efficiency you expect by carefully organizing
> multiple crews working on the same problem, i.e. disconnect
> crews, moving crews and reconnect crews, while you do
> significantly decrease the sense of team ownership and
> increase the likelihood of mistakes.
> 
> The same applies to driving faster.  If there are places you
> must slow down or stop and start then driving faster where
> you can greater increases your risk while not shortening
> your overall end to end move time.
> 
> If you have a time problem, the answer is to add more transporters
> and crews not trying to squeeze more moves out of the crew
> or driving faster.
> 
> Cheers
> David Woody


 Hi,

  Yes I was wondering about 'team coherence' also, it might 
  be better to have everyone dedicated to the task of moving 
  'their' antenna.   There is another issue also - seperating the functions 
  of the disconnect crew and reconnect crew implies a staggered
  start to the moving process - which means that the reconfiguration
  extends over a longer portion of the day - with the original timeline 
  operations are assumed to start at 7.00am and the last 
  until 15:00. 

  As we all know winds start to pick up in the 
  afternoon- in addition to possibly stopping antenna 
  reconfiguration (see seperate mail)  - there is a  psychological 
  impact at 5000m - you get irritated at the end of your work day when 
  your cold and all your papers blow around etc, etc. It sounds 
  silly but these human factors are important to consider  
  to reduce the chance of errors. 

  If one combines the operations of connect and disconnect 
  in one dedicated support team for each transporter  - then one gets 
  'team coherence' and you have move operations finished earlier
  in the day (see modified schedule below). Note that in this 
  case the total number of man-hours  worked increases slightly 
  since there is a new entry -00- which occurs because the 
  support  crew now arrives at the pad before the antenna - some this 
  time might be used for preparing the pad for antenna arrival.

 -----------------------------------------------------------------------

  Original schedule

  Each symbol between hyphens is assumed to take 0.5hrs.
 

  Prep/Load team         Tr-Pr-L1-Tr-Pr-L2-Tr-Pr-L3-Tr-Pr-L4

  Transporter 1          Tu-Tu-L1-Tl-Tl-U1-Tu-Tu-L3-Tl-Tl-U3

  Transporter 2                   Tu-Tu-L2-Tl-Tl-U2-Tu-Tu-L4-Tl-Tl-U4
       
  Unload/Install team                   U1-In-Tr-U2-In-Tr-U3-In-Tr-U4-In 


 -----------------------------------------------------------------------

   Modified schedule

  Transporter 1          Tu-Tu-L1-Tl-Tl-U1-Tu-Tu-00-L3-Tl-Tl-U3
 
  Transporter 1          Tr-Pr-L1-Tr-00-U1-In-Tr-Pr-L3-Tr-00-U3-In
  support team


  Transporter 2          Tu-Tu-L2-Tl-Tl-U2-Tu-Tu-00-L4-Tl-Tl-U4

  Transporter 1          Tr-Pr-L2-Tr-00-U2-In-Tr-Pr-L4-Tr-00-U4-In
  support team


   Key

   00 - do nothing, lost time (or maybe prepare pad for arrival 
         of telescope, uncover connectors in pad base etc).

   Pr - prep team  'shuts down'  antenna prepares antenna for arrival of
        transporter.

   In - Install team sets up  new antennas (i.e. get it ready for
   observations after transporter leaves)

    Tr - prep or install team travels - uses fast vehicle (30-40km/hr)
 
    Ln - Load antenna 'n' onto transporter.
    Un - Unload antenna 'n' onto pad.

    Tu - Transporter travels to next pad -  unloaded
    Tl - Transporter travels to next pad -    loaded

----------------------------------------------------------------------------

  Maybe all this is getting a bit detailed for now - on the
  other hand its useful to illustrate the fact that the effective move
  time per antenna per transporter  is not just (pickup-time + transport
  +set down =i.e. 1.5 -2hrs)  as people sometimes consider in
  configuration discussions.
  
  First for every antenna move there are two transporter moves, one
  loaded,  the other unloaded. Secondly, the time between when an antenna
  arrives at a pad and when it is ready to start calibration
  observations is not necessarily the same as the 'dead time' specified
  in section 4.2.14 of the project book which is the time 
  the transporter must stay at the pad while an antenna is
  loaded/unloaded.   If extra work must be done to get the antenna ready
  after thet transporter leaves, this implies another crew to do the
  installation and 'catch up' in a fast vehicle. There is then possible
  loss of reconfiguration rate due to 'synch up' inefficiencies 
  between the support team and transporter schedules.

      John
 
 P.S. Is there a specification somewhere in the Antenna documentation 
 of the total time between an antenna arrives at a pad and when its
 ready to start observing - what s the extent of the 'extra time'
 (if any) needed after the transporter departs?