On all construction sites there will be soils and materials to move. Whether a small residential site where you will have arisings from footings and service trenches to large residential or commercial developments where the quantities can be substantial. As an example at the SEGRO East Midlands Gateway I understand that over 4 million m3 of materials have been moved.
At many of the sites I am working on volumes are often in the range of 5,000 to 100,000 cubic metres and with a small number of sites volumes well in excess of this. The cost of moving these materials is therefore significant and often the estimated volumes to be moved or have been moved are not sufficiently accurate. Part of the problem can sometimes be the number of parties involved which can include the main contractor, civils contractor, developers and others. To add complexity of some of the large residential schemes you can have multiple house builders with everyone adding to the pile.
An additional factor is that historically volumetric work would be carried out by traditional survey methods. Traditional surveys are still the mainstay of construction sites and so they should be as they can provide the required accuracy. However for certain tasks photogrammetry surveys using a drone to collect the data are an ideal alternative.
Drones allow for the quick collection of data which can be collected to accuracies perfectly adequate for estimating volumes of materials. The best solution is the drone operators and surveyors to work in tandem and share data as that is win win.
For the majority of volumetric surveys I undertake I use ground controls to provide clients with the outputs to British National Grid. At typical flight heights (60/70m) with a good workflow the X/Y accuracy will be circa 30/40mm and 50/60mm in Z. The additional advantage is that with any subsequent surveys undertaking comparisons between surveys or say cut and fill analysis can easily be carried out.
One of the key aspects though is timing. Traditional surveys do take longer and require more resources. A typical residential construction site can be surveyed in an hour or two using a drone. Even large sites covering a few hundred hectares can be surveyed with in day. Thereafter with a good specification server the data outputs can be made available within a short timeframe, usually the next day. By means of the comparison I undertook a full day photogrammetry survey with a colleague recently and we covered circa 350 acres. This site had mulitple soil heaps within it and the surveying practice who undertake other work on the site had estimated that it would take them two weeks on site to capture the data with a further week to process the survey.
The speed at which drone surveys can be completed has also lead to more frequent surveys being undertaken. When a site can be surveyed and the client have volumetric data made available in 24/48 hours it enables sites to be closely monitored keeping an eye on volumes and costs. In addition profiles of tipped materials can be quickly checked against the landscape design and the movement of soils can be recorded. This is of increasing importance with regard to Material Management Plans.
With the additional fuel duty costs starting in April 2022 soil handling costs will further increase. Knowing how much material you have to move or checking how much has been moved will be become of increasing importance. Drones and photogrammetry surveys are the ideal tool to undertake this work and it is a cost effective solution. I have seen some sites go from a survey once every few months to much shorter timescales. One project I have been working on I undertook a drone survey every 2/3 weeks and the data outputs have been invaluable in managing costs and assisting with site management.
I believe a combination of these factors has lead to the increase in enquiries for photogrammetry/volumetric surveys. The cost effective and speed of delivery of accurate data enables improves site management and helps manage costs.
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