Many civil sites are being completed with machine control. The use of the equipment on the job site has become a reality, to the point that contractors have started to look beyond their current use of the possibilities in their hands. As many of you know, I have long been a proponent of leveraging data for a job site. I have worked with many of our clients to better use the data they have in their hands and drastically improve production and profits.
I will talk about several ideas that are good next steps for users of 3D site data. These are in no particular order of profitability, any site may or may not be able to use any of these processes. Not to worry, I will back up the explanations here with a video to better explain these ideas.
2D and 3D Points
Once the domain of survey, a point has specific and relative information. I’ll use points for laying out a curb arc as an example; 3D points for the PC and PT of a curb arc give us the location and elevations of that curb run. We know the slope between the points and paving elevation is an easy calculation. Next we add the arc center as a 2D point, now there is a pivot to actually swing an arc for form or string line layout. Increasing the power of points, we offset the curb line to allow the field to set string line for a curb machine.
Using earthmoving equipment to get the dirt right is a huge time saver. We also advocate the use of positioning technology for more than grading;
Electrical; It started with light pole bases and quickly escalated from there. We now regularly provide data as 2D or 3D points for;
- SES pads. The job has been checked so we are good with drainage and elevations on the site. The electrical service slab is easy to calculate from available regulations.
- Common area in-ground power. Many plaza shopping centers have electrical connections for decorations and kiosks. Knowing the 3D location of these allows for electricians to easily set these right the first time.
- Common area hardscape. Everything from playground equipment to benches, these additions need some type of base and connection. Know where things go and they can be done while access is easy and save re-digging to set later.
We have been providing utility layout for years. We show points 10 feet apart on the flow-line for pipe with horizontal offsets if needed. Structures are marked as well. The advent of successful machine control for excavators has allowed us to provide a trench network so the operator can dig trenches correctly the first time.
Other utility details can benefit from information provided in the data;
- FES’s, wing walls and valley gutters. These concrete structures are better done in rough grade but many contractors wait until near the end of construction and field fit. With a correctly prepared model there is enough confidence to build these when it’s convenient to the crew.
- Water lines are usually specified as a minimum depth below finish grade. We build the line in the data so crews can place it at any time and not require wheel trenching making a mess of the just completed grading.
- Subdivisions have utility connections for each lot, we handle this one of two ways;
- We can layout all the laterals and they are placed according to plan. When it’s time to make the connection, the rover is used to find the location of the pipe.
- When the utilities are not well defined or connections have to move, as-built shots are taken and we update the model for easy use in the future.
Taking shots along the way provide an ongoing record of what is being done. This helps to establish production rates as well as the basis for submittal drawings in the future. Here is one way to bring this into your workflow;
- I call this the “daily topo walk around”. While reviewing the work being done on a site, the superintendent has a rover and takes ground topo shots as well as items being put in the ground. In a perfect world, points would be coded but that is not critical.
- We often are asked to convert these walk around topo’s into as-builts or progress takeoffs. With the model on the screen overlaid to the topo points, we usually can figure out what the shots represent.
- Utilities are the biggest winner with as-built points. Before covering, if the top of pipe is measured, those are later converted to as-built drawings we put together for closing submittals. Many contractors have an issue with this, and we get it. It’s one thing to get the points but now the office needs to do full blown CAD drafting and plotting.
I will help to tie these ideas together in a video linked HERE. Please don’t hesitate to ask any questions you may have regarding these or other issues.