Chris, as you rightly observe this is a very complicated subject if you tackle it from the detail end. I have always made subjective order of magnitude allowances from the weather data provided by the Client and the project location along the lines of
1 Wind - 15 days per year totally winded (non working calendar days) off a 3 year coastal location project where tower cranes were critical to production
2 Sea swell - on Marine / Foreshore works - 10 days down time over tidal working height data
3 Weather windows in SEA countries (rain period lasts 6 months) - 2/3 rds production rate, but labour required to clean up daily.
4 High Temperature - above 50 / 60 degrees drop rates to 30 min / hr (UK indise working - additional breaks allowed, in/out barrier change time etc)
5 Low Temperature - below - 10 / - 30 degrees - never allowed for this as site methods to over come are in place (but obviously reflected in unit rate)
All factors declared in Basis of Schedule and submitted in bid to Clients.
Do you have any rule of thumbs?
Member for
21 years 8 months
Member for21 years8 months
Submitted by Rafael Davila on Mon, 2022-01-10 14:23
That there is high wind does not always mean a work stoppage but usually a reduction in production rates and an increase in activity duration. Similar to rain, wind is usually seasonal. The seasonal impact of reduced production rate cannot be overlooked.
Your deterministic and statistical models shall consider not only days lost to bad weather but also its seasonal impact on work hours, resource assignments, productivity and resulting changes in activity durations as the schedule moves and thigs do not go as planned.
If an activity is delayed by client from a high productivity season to a lower productivity season it may justify an extension of time as well as the associated cost increase; it should be easier to justify if the baseline model includes the calculation logic.
↑ open the options menu for a better view as desired
Good Luck.
Member for
24 years 9 months
Member for24 years9 months
Submitted by Patrick Weaver on Sat, 2022-01-08 00:24
If you want justificatin, you need data but there are challenges!
1. Climate seems to be changeing and becoming more severe (as well as generally warmer), this needs factoring in.
2. If you measure two or three factors, like wind, rain and temprature, you cant just add up the days..... some days will be too windy or too cold, other days you will find it is too wet, too windy and too cold (but only lose the one day). There may be a degree of correlation but generally you need to use a probabalistic modelling process. The 'portfolio effect' suggests the total allownace needed will be less then the sum of the individual risks.
3. Corrrelation between work and the event is lso an issue:
- Wind on a day (or at night) when you don;t need to lift has no effect on the crane
- Cold tempartures at night after a concrete pour may still be an issue although this can be mitigated by heating or 'blankets'
There's more basic infomraiton on risk at: https://mosaicprojects.com.au/PMKI-PBK-045.php BUT... this is an area where buying in an expert for a few hours really pays dividends - most of the cost is in gathering the data.
Member for
20 years 5 monthsChris, as you rightly observe
Chris, as you rightly observe this is a very complicated subject if you tackle it from the detail end. I have always made subjective order of magnitude allowances from the weather data provided by the Client and the project location along the lines of
1 Wind - 15 days per year totally winded (non working calendar days) off a 3 year coastal location project where tower cranes were critical to production
2 Sea swell - on Marine / Foreshore works - 10 days down time over tidal working height data
3 Weather windows in SEA countries (rain period lasts 6 months) - 2/3 rds production rate, but labour required to clean up daily.
4 High Temperature - above 50 / 60 degrees drop rates to 30 min / hr (UK indise working - additional breaks allowed, in/out barrier change time etc)
5 Low Temperature - below - 10 / - 30 degrees - never allowed for this as site methods to over come are in place (but obviously reflected in unit rate)
All factors declared in Basis of Schedule and submitted in bid to Clients.
Do you have any rule of thumbs?
Member for
21 years 8 monthsThat there is high wind does
That there is high wind does not always mean a work stoppage but usually a reduction in production rates and an increase in activity duration. Similar to rain, wind is usually seasonal. The seasonal impact of reduced production rate cannot be overlooked.
Your deterministic and statistical models shall consider not only days lost to bad weather but also its seasonal impact on work hours, resource assignments, productivity and resulting changes in activity durations as the schedule moves and thigs do not go as planned.
If an activity is delayed by client from a high productivity season to a lower productivity season it may justify an extension of time as well as the associated cost increase; it should be easier to justify if the baseline model includes the calculation logic.
↑ open the options menu for a better view as desired
Good Luck.
Member for
24 years 9 monthsHi Chris,If you want
Hi Chris,
If you want justificatin, you need data but there are challenges!
1. Climate seems to be changeing and becoming more severe (as well as generally warmer), this needs factoring in.
2. If you measure two or three factors, like wind, rain and temprature, you cant just add up the days..... some days will be too windy or too cold, other days you will find it is too wet, too windy and too cold (but only lose the one day). There may be a degree of correlation but generally you need to use a probabalistic modelling process. The 'portfolio effect' suggests the total allownace needed will be less then the sum of the individual risks.
3. Corrrelation between work and the event is lso an issue:
- Wind on a day (or at night) when you don;t need to lift has no effect on the crane
- Cold tempartures at night after a concrete pour may still be an issue although this can be mitigated by heating or 'blankets'
There's more basic infomraiton on risk at: https://mosaicprojects.com.au/PMKI-PBK-045.php BUT... this is an area where buying in an expert for a few hours really pays dividends - most of the cost is in gathering the data.