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Spreadsheet for time risk allowance due to weather

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Chris Wilson
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Hi, 

I have some historical data relating to weather for a specific region of the uk and am wanting to create a spreadsheet to calculate time risk allowance  based on it. 

So I can get say  pouring concrete TRA each month of the year with the winter months having more time risk or bricklaying, crane down time etc.

Does anyone have an example of something they would use for this?

Regards

Chris

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Rafael Davila
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  • There are many ways to model weather, you might argue yours is best, some force feed others to use their method. 
  • I believe in simple contract rules to split the risk of rain days while allowing the contractor to manage their schedule their way. 
  • For deterministic models I would target for dates earlier than contractual dates in the hope of making it on time as required by NEC.  How much time-risk allowance for rain?  It is a combined risk.  That is the question probabilistic models help to answer.

https://gmhplanning.co.uk/wp-content/uploads/2011/10/Newsletter-43-Contractors-float.pdf?8af1b3

In the NEC3 Engineering and Construction Contract (ECC), it is a requirement in clause 31.2 for the contractor to show provisions for time-risk allowance on each programme submitted for acceptance. It conversely becomes a valid reason under 31.3 for the project manager not to accept a programme if it is not shown.

Rafael Davila
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Be reminded that for different weather seasons the crews and productivities for same activity might be different.  If weather happens as expected there will not be weather delay days to claim but the activity durations will still be impacted.  A schedule model shall consider this in order to be realistic.

Rafael Davila
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Whoever wrote in San Juan PR you shall consider 200 rain days/year for purpose of adverse weather planning is way wrong, ignorance is bold.

Image-018

Puerto Rico is not Atlantis!

representation-of-Atlantis-1

If looking at similar report for London the number of rain days per month is ~15 days, using this as the threshold it would mean a contractor in London cannot claim a single rain within a month until over 15 days the work was stopped due to rain.  It is hard to believe contractors in London are required to plan for ~180 rain days per year where no site work is performed.

average-raindays-united-kingdom-london

Rafael Davila
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Even if within the norm, if client delays an activity from summer to winter, even if non-critical, the activity will take longer and the contractor might be able to collect additional compensation because it will cost him more due to client actions. So it might be no time extension but money.

Alternatively, if the contract does not provide for a consequential right to financial compensation, the contractor may have a claim for damages at common law.

Faulty generalizations may lead to further incorrect conclusions.

 

Zoltan Palffy
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Adverse weather above the norm is excuseable but not compensable. So no monies can be assoicated with the dealy due to weather because neither the owner or the contractor caused this to happen. So its a time extension but no monies.  

Rafael Davila
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https://www.hkis.org.hk/archive/materials/category/20160815113005.0.pdf

Additional Payment or Recompense: Generally, a delay caused by inclement weather is not a compensable event giving rise to additional payment or recompense. However, based upon the principles established above, the contractor may be entitled to recover the additional costs incurred due to delays caused by inclement weather, which costs were incurred due to the knock-on effects of a primary excusable /compensable event.

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Zoltan Palffy
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Planning for weather 

The schedule of anticipated adverse weather below will constitute the base line for monthly (or a prorated portion thereof) weather/time evaluation by the Contracting Officer.  On issuance of the Notice to Proceed and continuing throughout the Contract on a monthly basis, actual adverse weather days will be recorded by Contractor on a calendar day basis (include weekends and holidays) and compared to the monthly anticipated adverse weather days set forth below.

 Monthly Anticipated Adverse Weather Calendar Days: These are the number of days to be excluded in your calendar each month. These numbers are based on NOAA (National Oceanic adn Atmospheric Administration) for the GEOGRAPHICAL area that the project is located in.

 January - 7     February - 5       March - 6      April - 6      May - 8      June - 6     July - 6    August - 7   

September - 5   October - 5       November - 5     December - 6.

activity that are weather sensitive should be assigned to this calendar NOT INTERIOR WORK

listed belwo is a link to NOAA's number of adverse weather days per month by geographical location

https://www1.ncdc.noaa.gov/pub/data/ccd-data/prge0115.dat

 

ACTUAL WEATHER 

The number of actual adverse weather days shall be calculated chronologically from the first to the last day in each month.  Contractor shall not be entitled to any claim for time extension based on adverse weather unless the number of actual adverse weather days exceeds the number of anticipated adverse weather days, and unless such adverse weather days prevent work for 50 percent or more of Contractor's workday.  In preparing the Contract Schedule, Contractor must reflect the above anticipated adverse weather days on all weather-dependent activities.  Weather-caused delays shall not result in any additional compensation to Contractor.

 On days where adverse weather is encountered, Contractor shall list all critical activities under progress and shall indicate the impact adverse weather had, if any, on the progress of such activities.  This information must be presented at the end of the adverse weather day to COTR or its authorized representative for its review and approval.

If Contractor is found eligible for an extension of the Contract Time, the Contracting Officer will issue a modification extending the time for Contract completion.  The extension of time will be made on a calendar day basis.

Rafael Davila
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