I work on a lot of roadway widening / rehabilition projects for various cities. I alway have a difficult time estimating how long the construction schedule should take. Mostly I estimate it by using previous projects but I don't have any back up to support my duration. Does anyone know of a book (or anything else) that lays out typical durations for typical steps of construction of construction?
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How to Prepare a Construction Schedule?
- Thread starter raydefan
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It depends on why you are doing the estimating. If you are a contractor and you want to estimate for bid purposes, your own internal data will be your best guide...how much time did it take our crews to do this task under similar conditions...historical data. There are many estimating guides for construction work, but keep in mind those are generalizations. (R.S. Means & Walker's Estimating Guide)
If you are an engineer and you are doing estimates for time, I would certainly couch that as an opinion rather than an estimate...it carries less of a requirement for accuracy than an "estimate".
If you are an engineer and you are doing estimates for time, I would certainly couch that as an opinion rather than an estimate...it carries less of a requirement for accuracy than an "estimate".
I think the difficulty resides more than anything in the amount of resources the contractor is thinking to employ to excute the works. It is more or less attainable to know (to some extent) the produce of the typical teams or machines used for the different construction units. Persist always however the uncertainties of the final dificulties in worrying soils and the amounts of means tasked. So it is not infrequent, specially when time duration is primed in the contract, to find a contractor (or group of them) offering to finish (or if already contracted, finishing) the works in nearly half the time the allowed duration, or "what one would have thought a reasonable period".
This makes difficult that whatever your guess one can be extremely precise about the duration when soil, means, budget, primes and everything that makes the timeframe be affected has significant say. If money is available as thought, and no uncertainties were extant, it would be only to sum the compatible time use of a number of means assumed in the project. But that still would be assumption.
Seen otherwise, perhaps priming is one interesting way of approximating the timeframe to some wanted; the contractor would have incentive to allocate means enough to approach the timeframe, and conversely, the more suitable contractors to the work would be more interested in it because knowing their advantage, they can think on the incentive both as a partial assurance to get the contract and as well, of keeping some minimum benefit, and so would make the bidding process more selective from a target date viewpoint.
This makes difficult that whatever your guess one can be extremely precise about the duration when soil, means, budget, primes and everything that makes the timeframe be affected has significant say. If money is available as thought, and no uncertainties were extant, it would be only to sum the compatible time use of a number of means assumed in the project. But that still would be assumption.
Seen otherwise, perhaps priming is one interesting way of approximating the timeframe to some wanted; the contractor would have incentive to allocate means enough to approach the timeframe, and conversely, the more suitable contractors to the work would be more interested in it because knowing their advantage, they can think on the incentive both as a partial assurance to get the contract and as well, of keeping some minimum benefit, and so would make the bidding process more selective from a target date viewpoint.
project durations are based on the size of the crews and number of pieces of equipment in addition to the size and layout of the job. Generally, larger crew and more equipment means faster schedule and higher cost. However, some items such as procurement just can't be rushed and mother nature will always help with lengthening the schedule. Without an in-depth analysis of the actual work plan, you will be guessing at best.
This text is a comprehensive reference for project scheduling. It includes complete coverage of scheduling from the basics to advanced applications along with a detailed tutorial on the four most popular software programs; Primavera Project Planner, SureTrak, P3e/c, and Microsoft Project.
Construction Scheduling: Principles and Practices by Jay S. Newitt ISBN: 9780766808973
The Demlar books are also good:
Construction Scheduling with Suretrak
by David A Marchman ISBN: 9780766808973
Construction Scheduling: Principles and Practices by Jay S. Newitt ISBN: 9780766808973
The Demlar books are also good:
Construction Scheduling with Suretrak
by David A Marchman ISBN: 9780766808973
.
Open Workbench is a completely free project scheduling/management alternative to Microsoft Project and other such software applications...
.
tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation
Open Workbench is a completely free project scheduling/management alternative to Microsoft Project and other such software applications...
.
tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation
you develop a basic bar chart schedule w/ the computer programs listed above (takes a little getting used to them but not a lot) you can develop a duration for each construction activity by estimating the quantity of work divided by an estimated production rate (either from your own work history Or a generic guide like )
hope that helps
hope that helps
sodengineer
Civil/Environmental
If you work in the northern climates, construction time is based on the length of the season.
Another way of making a "back of the envelope" estimate is based on dollars/time. How long did the last project take vs how much did it cost? Very crude indeed, but it is a way of making a quick estimate. Then you can adjust based on the variables of the particular project.
Another way of making a "back of the envelope" estimate is based on dollars/time. How long did the last project take vs how much did it cost? Very crude indeed, but it is a way of making a quick estimate. Then you can adjust based on the variables of the particular project.
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