Serge,
Can you be a bit more specific?
For example:
1) Is everything well documented that you need to migrate? Is there any additional as-building that is required?
2) Are all the I/O's being migrated over to the new system? Do the I/O modules have the same number of channels, and are you preserving the I/O module assignment as is?
3) Are all the control logic, shutdown/interlocks, graphics etc. well documented? Are they staying exactly the same? Graphics alone have the potential to each up over 4-5 hours per point (we had to "re-do" them a few times as the client wasn't sure what they wanted). Also, with a new system, someone may want to "take advantage" of some new feature/capability/etc of the new system.
4) Are the programming languages the same (ex. ladder to ladder), or do yo need to translate/interpret and recode? Anything written in an older language (usually higher level control schemes)? Know of anyone who can still read it - I don't know of very many people who can read SOPL anymore).
5) Are you re-using exsting terminations or are you replacing those too with the new control system?
6) Are you re-using existing control cabinets, or are you using new ones?
7) Are you doing your cut-over hot or cold? In one scheduled window, or multi-stages over several? A hot cut-over, or multi-staged cut-over may mean additional real-estate as you stage both systems simualtaneously at some point in time.
8) What do you mean by material specification?
9) When bidding, do you need to pre-qualify any vendors? How many vendors will you be considering/evaluating?
10) Who is doing the work? Are you using your own inhouse personnel, an EPC/EPCM?
11) Is this a Lump Sum Turnkey, cost plus, hybrid type of contract?
These are only a small sample of factors that will affect your estimate.
Depending on your answers, the estimates may vary wildly.
