It's a question nobody have an absolute answer.
First of all construction is by mostly by manpower, human make mistakes, so that's an uncertainty
two, force of nature - monsoon season / rainy days, how to predict the weather???
three, cash flow - contractor / your own worker will stop work if not paid
four, u mentioned design, which means no approval from govt yet - approval time depends on Vit M & friendship
five, C.F.O - same as point no. four

pump more money to speed things up?
That's a bit hard to answer. If u use it to pay under table for govt staff, might not be the solution also. Use it for project also could be yes / no answer... Depends on u invest on plant / equipment, labour or material????
Cash flow management is one of the trickiest job for any developer

Project time & cost
Can be worked out. Basically u plan and try your best to stick to your plan!!!
And pray nothing stands in your way....

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Added on October 31, 2008, 12:43 pmGoing back to the original question. Time to construct semi-d / bungalow :
1) how many units ru talking about?
2) whether it's a semi-d or bungalow - semi-d means at least 2 units, bungalow means 1
3) what stage of design? Building plan? Sub-division?
4) site conditions - earthworks?? access to site etc etc
5) not only workers influence work speed. There are also other factors u have to consider. Generally material + labour = work. Make sure everything there is smooth.

If from start of land acquisition to actual start of construction is done within 1 year that's already called super fast track. There's no definite answers for u here cuz of so many uncertainties, and your incomplete question...