Bluefield Round Table – Right-Sizing Your Workshop

Of all the projects Bluefield gets involved in, one of the most common is helping clients determine the optimum size of their workshop.  Whether it’s building a new workshop, or expanding an existing one, sites all over the industry are looking to make sure they end up with a workshop that meets their needs, but without breaking the bank.

So we asked some of our specialists the following question:

When building or expanding a maintenance workshop, what are the important factors to consider to get the size (and cost) right?  Where do sites tend to go wrong with these projects?

Gerard Wood

The size is a very simple calculation.  We have done so many using simple bay utilisation forecasts based on previous time usage data, and also run equipment waiting delay simulations, but in the end the ratio of equipment per bay is an easy way to determine what is required. Six to seven machines per bay and the site maintenance guys are comfortable.  Eight machines per bay and they start to get pushed, nine per bay and they are stressed, ten per bay and they will be angry.

The cost is harder to determine because it depends on the equipment and capacities.  The large costs can be reduced by reducing the height of the workshop and the size of the overhead crane but there is a trade-off which means some work has to be done outside the workshop using mobile cranes and this will increase the risk. However, if capital is low this can be accommodated.  It is even possible to build a very large shed without an overhead crane for very low capital cost.  This does mean some tasks will take longer, be harder to achieve and increase the risks but it is possible. 

Peter Lee

Gerard, I also used to think 6 bays was ok and the number that first popped and would quote.  But now I think it’s too low.  Logic behind it is that if you take 8760 / 6 = 1,460 hrs maintenance per machine.  That is 16.5% downtime.  While I know we don't assume the bay is available 24/7, we also don't assume the equipment spends all its time downtime in the workshop, so as a rough estimate it’s close.  8 per bay calculates out to 87.5% availability which I think is a more reasonable figure to build a workshop bay off.  I think the reason why 6 per bay has come about as a guide is because we often deal with sites with poor availability. 

Gerard Wood

Nice points Pete, I agree with your bay to equipment ratios.  I also think 6 is too low because the people are happy and comfortable even with low availability.

Peter Yates

The reason I favour 6/bay to 8/bay is to allow for queuing which is more obvious with aged fleets, component change combined with breakdown and PM work

Peter Lee

Number of bays is the easy question.  I think the other question we need to answer is the trade-offs between having multiple bay sizes.  We always calculate the demand for the different class equipment so we can determine how many of each bay size we need.  I think part of the driver of this is that equipment has gotten bigger and thus we end up with every new workshop been built becoming larger to meet new equipment requirements.  What are the trade-offs of building new mixed bay sized workshops rather than a standard design meeting the largest equipment to be maintained?

Peter Yates

Workshop evaluations based on fleet demand, as mentioned, is a fairly tried and true calculation. The biggest effect on upgrades to infrastructure is capital being slashed.  While this is a business consideration and will inevitably occur due to changing market strength, we need to ensure we make sound decisions around how we distribute the now reduced funds.  Mostly teams will try to achieve the same outcome with less funds, which will always end with a poor result.  The best way to proceed is to use the reduced funds to contribute to the required end goal which may be some years down the track, always understanding the interim risks. 

Further Resources

One of our specialists, Keem Semmler, has previously written on Optimising Maintenance Workshop Capacity: read his article here.

You can also download a free tool for calculating workshop capacity requirements here.