(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?
(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.
I am looking for some guidance and personal experiences of programme scheduling for repetitive work on numerous sites. Although this relates to construction work, I feel sure the same principles would apply to inspection or maintenance schedules as well.
Eg…Project A has 50 sites, each with five distinct activities (each a different trade/subcontractor). The sequence of activities is always the same, but as each site is unique, the durations will vary. Because of time restrictions, each subcontractor will provide multiple gangs; so there will be multiple work strings (in this case geographic areas) ongoing at any one time.
The goals of the programme and project are:
- Finish all the work in the shortest time possible (as always!)
- Finish each site in a timely fashion (as we are accessing operational infrastructure).
- Keep each subcontractor continually employed (to avoid any stand down charges etc).
With such a high number of sites in progress at any one time, there are the inevitable daily changes which require re-sequencing. We are currently using traditional methods on a gantt chart (MS Project sadly), but there is so much inter-site and inter-trade logic to amend manually that it really becomes unmanageable. We have resorted to use a weekly schedule on Excel, but that does not show effects on the end date immediately.
We are trying out various methods involving resource levelling, priorities etc, but they each seem to be equally labour intensive and cannot satisfy all the three goals above. We are also investigating use of Vico or other ‘scheduling’ type software with a line of balance feature.
Has anyone encountered similar work and can provide any help in this field? All software recommendation, tips and techniques welcomed.
Thanks,
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Ian,
LOB software usually does not level resources and I expect that in your case the number of gangs is restricted and leveling is must. In other case everything could be done simultaneously.
In the example I prepared each subcontractor had only one gang and thus the works were organized in accordance with the resource restrictions.
Line of Balance is one of many Spider reports, nothing more. After calculating resource constrained schedule you can get the result as Gantt Chart, Network Diagram, Linear Diagram (LOB), etc.
Thanks for all the replies.
Steve,
Thanks for the link, very interesting and well written article – and i can see its use in the future as a very good method when drafting acceleration/recovery programmes. However, the critical path is not really the main issue here; because the individual sites are essentially interchangeable in their order and there are multiple units of resource for each trade the critical path changes all the time.
i.e the 50 sites could be broken down into 5 mini-programmes of 10 sites each - the biggest prioritiy is utilising all resource in the best way and finishing all 5 strings of work within the deadline.
Gary,
I will drop you a PM, I believe you may know the project in question as we share a few contacts. You are certainly right to say that the priorities can conflict, and often do so or can change from week to week! But that is a reality sadly.
I will try following the dummy resource method you mention and let you know the results. It would be ideal if such difficulties could be overcome on a gantt chart and using our existing software MS Project (EPM) but I am getting more convinced that Spider/Vico or other scheduling-focused software is a better solution.
Vladimir,
Thanks for your reply and assistance – that looks promising and we are certainly considering sceduling/LOB software packages as I have already mentioned. I will message you a file of our programme to see your thoughts.
I tried Spider Project with smaller set (8 projects with 5 activities each) and the schedule looks acceptable.
If you will send me your project as Microsoft xml I can try to schedule it in Spider Project.
My results are below:
If you are interested send me private letter. Best Regards, Vladimir
Ian,
I have never used the resource levelling functions of MSP, so don't know how powerful it is, or how optimial a solution it will give you, but levelling should be the way forward here.
To satisfy the requirement "Finish each site in a timely fashion (as we are accessing operational infrastructure).", try setting up a dummy resource called "total time on site" at 1 unit per day, loaded on the summary bar for each site. I would hope the levelling algorithm would try to minimise this resource by avoiding gaps between trades.
P6 is not brilliant at levelling, but it will let you prioritise activities by a number of different variables, including free float. This would also help to minimise gaps between trades. Don't know if MSP can do this too?
Again I have no personal experience, but I have heard good things about the levelling functionality of the Spider Project software. -Vladimir from Spider patrols the forums regularly, and may be able to advise if Spider can do what you need if MSP is letting you down.
Finally bear in mind that there may be cases where two of your objectives are contradictory -eg in order to keep subbyA busy, you may need him to start & finish his work on a site before subbyB will have a gang available to start his work, thereby extending your total site time. I think you will need to decide which of your objectives will take precedence in such cases.
Good luck, andlet us know if you find a solution -I may have a similar scheduling problem coming my way in the next few months, so would be glad of any tips!
Hi, Ian.
I can't help with all your issues (especially without knowing the detailed schedules). But in terms of:
"not show(ing) effects on the end date immediately", it sounds as though computing (and re-computing with each change and iteration) the Drag of each critical path activity would be very helpful. (If you want to know exactly what Drag is, try teading this article in the Jan/Feb issue of Defense AT&L Magazine):
http://www.dau.mil/pubscats/ATL%20Docs/Jan_Feb_2012/DATL%20Jan_Feb2012.pdf
The only two packages that compute Drag are Spider Software and the Sumatra Project Optimzer, and add-on to MS Project. I believe you might be able to download a free trial of the Sumatra product here (although it says the offer expired at the end of 2011, so I'm not sure):
http://sumatra.com/projectoptimizer/projectoptimizer.htm
Good luck with this, and let me know if computing Drag helps you deal with your problem.
Fraternally in project management,
Steve the Bajan
Email: PPadmin@planningplanet.com
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