Technology has led to various advancements in different industries, including construction. 3D modeling, for instance, is one of the most impactful forms of technology used in construction. 3D models improve accuracy and efficiency by assisting in strategic site layout planning, including utility and landscape mapping. The use of this technology simplifies the site layout planning process and improves accuracy.
Understanding Site Layout Planning
Site layout planning is a critical aspect of construction project management that involves strategically arranging various elements on a construction site. This process ensures that resources and space are used optimally and construction activities are conducted efficiently, safely and in compliance with relevant regulations. Civil contractors often use computer-aided programs to plan and visualize a construction site. Traditionally, this was done using 2D methods, but it is now enhanced by 3D modeling.
The main elements involved in site layout planning include:
Site analysis: Before creating a layout, a thorough site analysis is conducted to assess various factors such as the topography, soil conditions and existing infrastructure.
Positioning of temporary facilities: This step involves identifying the site facilities that will be required and where to place them. These facilities include site offices, storage areas, machinery and equipment zones and worker facilities such as break rooms and sanitation facilities.
Access and traffic management: Access requirements should be considered after the necessary facilities have been identified. This includes ensuring workers can move safely between work zones and welfare facilities. It also includes considerations of the routes that trucks and machinery will follow to move materials in and out of the site. The placement of utilities such as gas, electricity and water must also be considered when planning a site layout.
Materials handling and storage: To prevent delays, materials must be placed to optimize the handling process. They should be stored close enough to the work site, but not in a way that hinders workflow. Secure areas should also be provided for fragile or hazardous materials, considering environmental conditions like heat or rain.
Safety and compliance: Safety plays a critical role in site layout planning, with features such as fencing and barriers as well as emergency access.
Optimizing workflow: The layout should streamline the construction process, ensuring smooth transitions between different phases. It involves placing machinery where it can be used efficiently without needing frequent repositioning and material flow, where materials can be efficiently moved from storage to the point of use.
The Role of 3D Models in Site Layout Planning
3D models play a crucial role in site layout planning by providing a comprehensive, detailed construction site representation. These models enable project stakeholders to visualize the site layout in a realistic and immersive manner. By leveraging 3D technology, engineers can create digital replicas of the site, complete with accurate terrain features, existing structures and proposed elements. In most cases, the site layout model includes:
Zones for particular activities
Site offices
Welfare facilities
Off-loading, temporary storage and storage areas
Sub-contractor facilities
Car parking
Utilities, including electrical power, lighting, water distribution, drainage and communications technology
Temporary works
Areas for the construction of mock-ups for testing
Fabrication facilities
Emergency routes
Entrances, exits and other access points
Waste management and recycling areas
Site hoardings and existing boundaries
Signage
3D models enable accurate spatial planning via precise measurements and placements of elements on the site. Contractors can use these models to ensure that all components, such as buildings, roads, utilities and landscaping features, are accurately positioned. They can also check to ensure the site layout aligns with project requirements. Visualizing the site layout in a 3D environment helps optimize how the space is organized, ensuring efficient use of space and resources. It also allows for better decision-making and reduced errors in site layout planning.
Utility Mapping With 3D Models
3D models integrate utility mapping by precisely planning the placement of essential services. For example, you can map where to place electrical equipment, such as light poles, electrical service slabs and connections for electrically powered elements like decorations, kiosks and signs. With 3D models, electricians can set these connections up accurately and quickly.
Other utilities you can map using 3D technology include natural gas lines, water and wastewater piping and gutters. The information provided by the models gives crews confidence that they are making the most efficient placement. They are better prepared since they know where every element will go, helping avoid the need for re-digging in later stages. You can include several other elements in a 3D model, such as benches and curbing.
Landscape Mapping and Planning
Landscaping projects are becoming more demanding and complex, which is why data accuracy is increasingly crucial. Technology has provided landscape architects with a unique opportunity to incorporate new standards into traditional methods.
3D models allow landscape architects to create more accurate, data-driven designs that meet the highest operational and aesthetic standards, giving them an edge over competitors. They can integrate data to develop dynamic and detailed representations of projects. 3D models aid landscape architects in the following ways:
Visualization: 3D models can be useful in visualizing and planning landscape features to ensure they complement the overall site design.
Cost reduction: With the correct data, you have the information you need to maximize the financial resources available in each project.
Efficiency: Data processing and 3D modeling services enable you to clearly define your project’s specifications and scope.
Communication: You can use 3D models to properly articulate your ideas to stakeholders.
A lot of data needs to be collected to create these 3D models. To compile information from different sources, a solution is needed that can transform the collected information into usable data, which can then be used to create construction documents and site plans. Technology that’s often leveraged in data preparation for creating 3D models includes:
Light detection and ranging (LiDAR) solutions: Create detailed 3D models using advanced LiDAR technology that account for different geographies.
Photogrammetry mapping: Enhance the accuracy of construction projects with integrated photogrammetry mapping.
Benefits of Using 3D Models in Site Layout Planning
There are many benefits of using 3D models to plan site layouts, including:
Improved decision-making: 3D models allow construction contractors to visualize different potential outcomes with varying site layouts. This capability enables them to assess the impact of factors such as functionality and cost when making decisions, leading to more successful projects.
Increased efficiency: 3D models streamline the site layout process by providing a detailed visualization of the project. The visualization allows designers to experiment with different layouts and make informed decisions, which saves time and resources.
Enhanced collaboration: With 3D models, construction workers, engineers and architects can access a realistic representation of the site layout. They are able to easily understand and contribute to the planning process, reducing misunderstandings and improving communication.
Mitigated risks: Using 3D models helps pinpoint potential risks before construction begins, such as clashes in building systems. By identifying issues early in the planning stage, civil contractors can take a proactive approach to reduce the likelihood of delays during construction.
Improved communication: Traditional 2D site plans often leave room for misinterpretation. However, 3D models are more detailed and offer a more accurate representation of a site layout. They are also useful in explaining complex design features and answering questions clearly.
Enhanced creativity: 3D models empower planners to explore creative opportunities and experiment with different design solutions. They are able to visualize site layouts from different perspectives and angles, making changes as they go to see the impact on the overall layout.
Reduced project costs: Using 3D models minimizes the need for rework and changes during construction, allowing for projects to be completed within budget. Since potential issues will be identified earlier on in the planning process, it can reduce costs related to rectifying errors.
Contact Take-off Professionals for Accurate 3D Models
3D models are a valuable tool that promotes informed decision-making during the site layout process. At Take-off Professionals, we transform your data into accurate 3D models to help you achieve the best results possible. We have a team of qualified technical staff and engineers who are experienced in creating 3D models for site layout planning, so you can rest assured that your projects are in the hands of experts in the field. Many of our competitors use subcontractors, but our team is made up of full-time employees who take care of all aspects of building 3D models.
We’ve been in business for over 20 years and have built a solid reputation for providing exceptional customer support, paying attention to detail and delivering accurate and timely results. To simplify placing a work order and reduce turnaround times, we have an exclusive platform where our clients can add files, notes and other important information that would be useful in 3D modeling projects. Contact us today to learn more about how our 3D models can impact site layout planning and improve your project outcomes.
The Bell Helmet Company once had a magazine ad with the statement, “If you have a 5-dollar head, get a 5-dollar helmet.” Wise words when you think about protecting your brain. The interwebs have done a great service to us; we now have experts in every corner of the world. I admire some of them but do an eye roll with many. As one of the original innovators in the industry, I’m not pulling rank, I am speaking from experience. I just do not like to hear bad information being passed off as truth.
Regarding those who advertise low-cost data, I have but one thought: If your work was worth more, you would charge more. So many people are not invested in making a good product, but just making a product. I have spent my career working on delivering data in the fewest mouse clicks possible. We like to bill for work done efficiently by trained professionals who have been trained by experienced mentors familiar with a lot of different data issues. When the experience issue gets brushed aside as a “nothing burger” by more recent entrants to the data industry, one has to look at the actual time it takes to decode and properly set up a project.
Many times when inexpensive data gets built, it is just converting a surface built by the engineer at some point in the design. This is usually done to get a rough dirt number so that some quantities can be put on the plans. When doing a takeoff and I was close to the engineer’s numbers, I went through things again. Those quantities are usually never close. The surface is not only a few changes behind the plans, it lacks the detail for successful grading. Here is why proper data takes a bit of time.
Initial Data Files
We receive the plans and CAD in addition to a work order for the job. We often find that the plans and CAD are a mismatch. Not a big deal. Just find out which of the two is correct, get the current file and we are good to go. For every job we do, the files get touched by no fewer than three software platforms. It is not cheap to have all that horsepower, but we can do a more efficient, competitively priced job with them. We need to read the plans and relevant specifications to insulate our client from issues. We want no surprises. Notes on the job guide our work, then we start building.
The Big Picture
I will use a sample project to give you an idea of what good data, coupled with 25 years of experience, looks like. The data engineer working on the job has a deep bench of talent to call on for advice. A great advantage that goes a long way in securing a good job for our clients. Here are the basics:;
The entire job consists of a building with a basement, parking for 200 vehicles, and a long entrance road.
There is detailed landscaping along with a lot of drainage work, (wet part of the country).
We also need to build an initial water management surface, as all the water needs to stay on the project. Watershed pollution prevention.
Initial CAD Work
We have detail sheets that we populate for our clients. Surface density, line colors, file types, and delivery method are a few of the things that make a job easier for our clients’ field crews. As a former field hand, I like to be in their corner and do everything possible for them. Five minutes of work in our office on the computer saves 30 minutes balled up in the cab of a work truck, trying to change something. Here is the process.
Civil 3D files can be feature rich. That is good news for somebody doing poor work and just converting a surface. In our world, that is something we delete to make the file smaller.
Lines have become critical. A grade checker will want a 3- foot back of curb 3D line to set string or hanging forms. A blade hand wants to snap on an edge of pavement line to shift the blade 2 feet behind the curb for slip former access. All of these lines need to be in the correct direction, void of any overlaps and breaks. That takes time.
With the paper plans ruling, we need to confirm that the job looks like the CAD; this can be time- consuming and frustrating. The best that one can hope for is a spot check with budget data work.
In the early days, we worried about file sizes, but not so much anymore. It still makes sense to show only the lines necessary to complete the work. Text needs to be simple and in a format that does not steal bandwidth from a controller.
Surface Components
Since the beginning of the data business, we have used the same elements for building data. Each of these must be carefully created and work with the other parts.
2D Lines
Contour lines are really 3D lines as they are elevated. But because it is all the same elevation, we call them 2D lines. How those lines are produced is something the model builder will find out if they are doing their job.
Sometimes points are placed on the surface and contours are produced later.
Contours can be drawn by hand to show intent. That means you cannot use them on the surface, but they are nice to look at.
Contours are made first to show slopes and sheeting water, usually in a parking lot. They are interrupted later for islands and other features.
In our example shown above, the contours were drawn in later to show the general slope of the parking lot. The slope arrows provide some faint clues on how the water is moving. This one took some time to get right.
3D Lines
When doing curb, the elevation of a line changes. We first need to plug in the numbers from the plans, then fix issues that are obvious.
If there are things that do not make sense, we need to run a request up the ladder and get more information.
In our sample project, the slopes in the ADA parking areas are out of spec. This is not an issue; we check the percentages and make them right. If they do not fit, we need to talk to someone. A quick once- over of an engineer’s surface will not catch these small details.
There are a lot of things we can do with these lines. Offset the flow line to get top back of curb, even extend that line for staking. This requires us to create lines, which cannot be done from a surface found in the original CAD.
Points and breaklines
I have always used points to create an absolute elevation. Think of the rim of a storm grate.
Points are used by our clients to layout improvements.
Points are useful for curb radius points as well as footings and building corners.
We will do layout of light poles, playground equipment, electrical lines, and SES pads. The list is long.
Breaklines are used to make a surface respond the way you want it to. Triangle linking is indiscriminate and these lines make features look like the design. This could be from a simple ditch to parking lot flow lines.
They become the final tool to get things looking right. They are a necessary and sometimes frustrating tool. Too many breaklines and the surface is strained, too few and details get lost.
Summary
In order to use a surface made by someone else, the above issues would need to be addressed. It takes longer to take things apart and put them back instead of doing it right the first time. Cheap data uses information that is not correct. A few checks and it lands on your site. Instead of a surface you have a minefield, not knowing where the bad spots are. There is still a culture of “fix it in the field.”. This does happen when provided with too little information, but it is the rule when dealing with marginal work from less -experienced model builders.
I, in no way, am faulting engineers for this. Any surface made by them is for a different purpose. It is the job of the model builder to get inside the plans and understand the site from a singular point of view. Will it perform as intended? Years ago, I wrote an article in Machine Control Online Magazine. The title was “You Pay Us to be Nervous.” You just cannot do a good job in a couple hours.
Spoiler alert, I’ll give the answer first, then explain. As a major data engineering firm, we require the regular use of Civil 3D. For those of you that provide data for your own company, you can usually find workarounds to save money. Once you have the budget to acquire Civil 3D, you’ll have to learn how to effectively use the program.
Personally, I do not know the program and never really liked it that much. It is not very intuitive and took a long time to learn mostly because the classes were taught by geeky users who were thrilled at how many mundane things could be done with the software instead of doing work. But that is a discussion for another day. The most common task I would perform would be the conversion of a MicroStation surface to something we could use in other programs. I got some training, and everything worked great for a few months. Then the software was upgraded, and my cheat sheet was worthless. Back to the drawing board. I had to perform other tasks as well in MicroStation that had varying degrees of success with upgrades.
What are the benefits and risks of investing in Civil 3D?
Remember, you may know how to do something today, but an upgrade may change that routine. Here are some things to keep in mind.
To license a seat of Civil 3D, you are looking at about $2,500.00 per year.
You can rent the program with tokens. More on that later.
If you do not know what to do, training will be required.
It is a frustrating program to use and difficult to learn a few commands without being familiar with the structure of commands and processes.
It takes at least a week or two of training to get used to the program to perform your desired application.
Training may not be targeted to your needs and could require you to learn a lot of things you will never use.
CAD Tokens
The use of tokens for Autodesk Products is a new option to purchasing software. I like the concept because I use Revit on a sporadic basis and cannot justify a yearly subscription. A look into the cost of Civil 3D tokens resulted in the following data.
Tokens are $3.00 each
Civil 3D costs 9 tokens ($27.00) per 24-hour period
Shut down the program during the 24-hour period and the tokens are considered spent for the session (Pro Tip).
If you are comfortable using Civil 3D to perform the required tasks, then this is a good deal. If you are new to the program, or a few releases behind, it will be better to license a seat and access the program on a regular basis for training and use. It will be much less frustrating.
That brings up the issue of training. The wonderful thing about Civil 3D, and all Autodesk products, is the wealth of training resources on the web. Do some research, as the quality varies widely, and certain You Tube channels and websites have different areas they cover. I will start with a search on what I am looking for and drill down a couple of rabbit holes until I get to the information I need.
Let us say I want to get rid of splines in a drawing. They make a mess in non-CAD programs, and it is best to convert them in CAD. A quick search gave me a tip from the Autodesk site. Quick and easy.
I will also save video tutorials from various sites, and then bookmark those sites to reference as needed.
These are obviously not crazy deep dive commands and once you go through them a few times you will remember how to use them. You can also refer to my article on “Seldom Used Commands” that shows how to build a log and cheat sheet to speed up the process.
After you have convinced yourself you cannot live without Civil 3D, or you are trying to get somebody else to buy it, what things can you do with it that cannot be done in non-CAD programs?
I must first warn you that non-CAD vendors will tell you that they can import CAD elements and that is not always the case. When all you have is a hammer, every problem looks like a nail. I regularly work on CAD files for our staff and extract items that come in messed up. You sort of do not know what you are missing with importing tools used for outside files. To test that idea, verify the import looks just like the PDF plans, there will usually be some items missing or corrupted. This is not always a bad thing but miss one good layer of spot elevations and your frustration will make you long for a seat of Civil 3D. Go and spend a few tokens and make it happen.
What Can You Do With CAD?
Here are a few of the things you can do well in CAD that may not work as good on other platforms.
Splines: I mentioned this before, but they can cause real issues if not converted to polylines.
Blocks: CAD blocks do not always import well and sometimes not at all. You can Burst or Explode the blocks.
Non-CAD programs can only Explode if they import the blocks. The Burst or explode is a whole article on its own, research it if you are interested.
Alignments: Civil 3D corridors are feature rich elements that we do not use. Our clients pay us to make the corridors in the non-CAD software they use. We can, however, extract the alignments and use them after checking their accuracy. It’s a great tool for long roads and rails.
Surfaces: A lot of existing ground surfaces are Civil 3D surfaces and do not import well into some non-CAD programs. A little work in CAD makes things easier.
Text: M-Text can cause issues on import due to the sizing attribute it gets in CAD. Changing settings of these will make them work better.
Leaders: Sometimes not a big deal but dense data has a lot of arrows and knowing where text points are can help. The problem can be the leaders are dynamic in CAD and will not appear on import.
This is a screenshot of the dropdown menu for Quick Select. These items should be made basic CAD elements if possible to improve the import of the data and for faster refresh rates on the screen.
There are more examples I deal with daily, but these are just a few of the most common ones with easy resolves. For help on your next big project, don’t hesitate to give us a call at (623) 323-8441! Our expert engineering staff is here for you.
Creating an exact earthwork estimate is an essential first step to many takeoffs. You want a bid that accurately reflects the cost of labor and materials so you can get the project fee you deserve and minimize financial risks. At Take-off Professionals, our experienced team of engineers creates precise earthwork estimates based on your designs.
This post will explain what earthwork estimates are and the three methods we can use to create them.
Fundamentals of Earthworks: Excavation and Embankment
Earthwork is the engineering process of moving, removing or adding soil, rock or other materials to change a specific location’s topography. To create a 3D earthwork calculation, compare the location’s current topography with the contractor’s proposed design. The process of creating an accurate earthwork estimation consists of calculating how much material the contractor will need to add — or fill — and take away — or cut.
Cutting is removing material from the site, and filling refers to adding material. Both are crucial for creating the topography reflected in the contractor’s design. Engineers will calculate the cut and fill quantities to reach a mass balance and use that mass balance to provide an accurate earthwork estimate.
Elevate Your Project Efficiency with Accurate Earthwork Estimates
At TOPS, we deliver precise earthwork estimates and essential 3D data to drive your project forward. Our models aid in enhancing project efficiency and accuracy, regardless of project size, enabling successful completion.
There are three main estimating methods that engineers can use when creating 3D data for earthwork in construction. These methods calculate the dirt and material quantities required while providing mass haul analysis for the construction site. However, some are more accurate than others.
Method One: The Average End-Area Method
We typically use the average method for smaller projects that require us to ascertain the levels at all grid points. Because this method is the simplest of the three, we can only use it when a project requires either filling or cutting. The average method provides inaccurate estimates if you use it for projects that use both cutting and filling.
Method Two: The Grid-Cell or Block Method
Our team uses the block method — also called the division of square method — to determine volume for medium-sized projects that require leveling. The block method is more straightforward than the section method and more accurate than the average method. You can expect some margin of error when using the block method on projects involving both filling and cutting, but much less than the average method.
Method Three: The Cross-Section Method
The section method is the most complex and precise way to calculate an earthwork estimate. We use this technique when working on large-scale projects, such as dams, railway systems and roads. Although the section method requires many steps and more complicated calculations, it’s the best method to ensure a precise estimate that will save you money.
Precision Earthwork Estimates with Take-Off Professionals
Our team of full-time engineers is on hand to provide you with precise earthwork estimates and essential 3D data. Contact us to learn more about our products or request a quote for our earthwork services.
This update will go over the newer concepts for design/build on a civil site.
These concepts have done a lot for large roads and in the vertical world where tenant build outs change daily. Generally, engineers that do not have enough staff and are worn down will welcome input from you and your staff. There are several considerations you need to address for this type of relationship.
Beware of a CMAR (Construction Manager at Risk) projects. They can be profitable but need to be fully vetted on the front end. Change orders are usually not an option. These contracts are an effort by the owner to get fixed price work so know what the project entails.
For the civil portion of a project that is done in close contact with engineers and owners, things can go fast. Changes are easily approved, so be sure you propose answers. After all, this is a team job, and you will be tasked with solutions that keep the job on schedule and budget.
Money becomes more transparent. The billing is at cost plus, or a fee above agreed upon operating and materials costs. It’s not a problem, just a different approach to billing and verifying pricing. Price increase adjustments for material cost increases need to be included.
We have all been there. Get a set of plans, open them, take a look, and wonder what possessed the team responsible to perform the way they did. I started my career in the offices of a developer/builder. I got to see firsthand how the process goes, as well as the changes that must happen. The journey often ends up with something completely different than originally planned.
Development Types
There are two types of builder groups; public and private. For this discussion we will look at private work. Private work can be further broken down into commercial and local. This article covers commercial builders.
Commercial Development
In the civil construction world, commercial development relates to projects done by a large company in different geographic areas. Think of a big box store or restaurant.
Here are some general specifications:
They have centralized operations and often work on sites they may never visit.
Their staff does a lot of projects. Operations are streamlined and efficient. When they get busy, questions can sometimes take too long to get answered.
They have little emotional investment in the process.
Deadlines and opening dates are the only thing that matters. I have seen corporate firms do full redesigns to placate local building officials without blinking an eye.
They are not afraid to spend money to get things done. The fast-track construction concept came about just for big box retail.
They are not used to dealing in your area. Try not to suggest, “we do it this way around here.”
Junior people handle stuff first. Get used to clearly explaining an issue so the next person up the ladder has all pertinent data.
The Process
The biggest factor in commercial work is the time from land acquisition to opening day. Pay and bonuses for employees involved are measured by expediency of their work. A month delay for a big retailer translated into hundreds of thousands of dollars in lost revenue. They still have a bottom line. Quick decisions to problems are important to keep in mind.
Over 15 years ago, I wrote an article for a magazine that included the thought, “all the good dirt is gone.” The nice flat building sites with well compacted soil and no garbage were all developed and all that is left is the stuff that is expensive and difficult to work with. The land is acquired by the company and the process begins. For this part, both commercial and private work follow the same course.
The selection of an engineering firm takes one of two roads. The company has a nationally registered firm, meaning they have people with a license in each state they work in. The other track is to contact a local firm that has experience in the area to get things going. I have not seen much difference in the choice. An advantage of a local firm is that if you get the job, communication could be smoother.
Next, a survey of the property is performed and submitted to the engineer and owner. These will be ALTA Surveys. This means they conform to the American Land Title Association guidelines that follow strict standards for real estate transactions. I remember a job involving a McDonald’s restaurant in Las Vegas that had three surveys performed to verify the plot. The land was priced by the square foot, so every little bit made a difference for all involved.
The survey is just 2D and clearly outlines the property boundary. At the same time, a topography map is usually made to provide the engineer with a starting point.
Site Specifics
We all know what a Wal-Mart or Home Depot looks like. When it comes to the area surrounding the building, this is where things must conform to the site purchased. The process being backwards, at least to us civil types. The footprint of the building is decided. How big a structure needs to be built to supply the anticipated traffic. From there, the civil engineer takes the job. There are fixed and fluid variables that enter into the site design equation, and many of them are decided by local codes.
Drainage needs to be sorted first. Knowing how big the building is, how much of the project do we need to dedicate to drainage? Most local codes will let you work in cubic feet of storage, meaning deeper basins that take up less area. Some require a percentage of the site have allocated green space, which also can be retention basins.
Number of parking spaces may be called out by ordinances. Handicap spaces are also controlled that way. This is the reason you may see a lot of accessible spaces in some parking areas and not many in others. Local codes adjust that. The only requirement is they do not allow less density than the ADA guidelines outline.
Access is next. We would love every entry to have a nice long decel lane, wide access driveways, and plenty of entrances and exits. The site will restrict this as well as the roads they enter.
The owner and engineers will need to look at the aesthetics and curb appeal of the project. Nobody wants to enter an unwelcoming site. Green space, trees, and easy access are all key.
There is no such thing as a great parking lot design. All ideas have drawbacks. Make something easy to navigate and somebody will find a way to gum things up. Useable area has the biggest impact on one way or two-way lot lanes, nothing else.
With these less than desirable plans in your hands, you bid the job. The hard bid was won, and it is time to work. I have seen many a small to medium contractor do a bang-up job for an owner and get asked to do more on a negotiated basis. Keep that in mind when you look at this type of work.
My best advice is to submit your concerns right after being rewarded the job. You already have the list of concerns that was made during the takeoff, estimate, and bid where contradictions and confusing details were presented in the plans so this should be easy. Addressing concerns at the start will accomplish two goals, it shows that you’ve studied the plans well and gives you the chance to bail if you do not like their answers.
Change orders are normal. Do not hesitate to fully explain the problem and solution. Your submission will most likely pass through two or three people before it gets approved.
Fully explain the issue requiring the change order.
Propose a fix and the cost associated. Remember, never ask a question without providing your own best answer.
Make your submittal stand on its own. In other words, if I read your change request and have any questions, you did not do your job well enough.
Site selection, design and construction are all handled by different people. Seldom does one person follow a project through. Make sure everything is written down. Communicate with all stakeholders so that there is no misunderstanding when things get handed off.
Update: May 12, 2022 – I got some questions after posting this article to address. As always, do not hesitate to contact me with questions.
A common mistake, “I always use the surface from the engineer and things work fine”.
Let me unpack this and discuss the reasons why you should never trust a surface you did not build.
You are one of the lucky few who’s engineer actually understands the 3D world. This is the exception and not the rule.
Your expectations are low. Maybe you do not have machine control. You also could think that machine control just gets you close and final grading has to be done by an experienced blade hand. If your model cannot go into a machine and cut a good grade, it’s time to up your game.
The job may be dynamic. In other words, changes are happening so fast, the engineer actually pays attention to the model and gives you portions to work on that are close enough to get things right.
The bottom line is you don’t know what you don’t know. When an “OK” model is all that is ever delivered to the field, everyone assumes that is as good as it gets. One of the biggest sources of new business for us is when someone from one of our client companies moves to a firm that has substandard data. They point out the issues of the data and point out the advantage of quality work.
There are many reasons you may be compelled to do a quick fix on a bad surface and get it in the field. We never use an engineer’s surface sent with CAD files because we are being paid to build it correctly. From a time-management standpoint, we can build a surface faster than the time it takes to break it apart, find the issues, and put it back together. When someone finally gets the files, and crews have been on the job for three weeks, a quick (and very dirty) surface turned around overnight is better than nothing.
Everybody talks about only sending out “perfect” models. My hat’s off to you, most jobs do not get enough warning to make them pretty from the start. I am speaking of the people in the office who get the call four minutes after the CAD files hit everyone’s inbox and the voice on the other end is wondering where the model is. That is the reality we deal with. Time to figure how to make this work.
The Surface Defined
When I talk about a surface, we are looking at the 3D elements that are elevated to make a model, contours, 3D lines, and points. Surfaces can be any combination of these three things. I will go through the advantages of each data type for a quick surface and what they do (alone or with other elements) to get you moving.
Contours
Contours are referred to as 2D lines because they are all the same elevation and still 3D because they are part of a surface. Contours undergo a lot of changes during data production but are often a quick way to get something out.
Initially, these contours do not look so bad. You need to trust me; they are a decent representation of the surface.
Creating a quick surface shows there are some problems. In this case we cannot send this out, work needs to be done. This may be considered work that takes too long for a quick start, but the spikes and bad information will cause more issues than they fix.
Line density is all over the place. Some areas have long runs without anything and it is too dense in other spots. This is common for a civil 3D file.
It needs break lines in order to make sense. A ditch is being blown over and slopes are not smooth and even.
Here is a screen shot of the improved density and some spike removal. At some point, you need to decide what a contour only surface should have. Here are some thoughts:
This is for rough grading only. You will not get detail to get you within a half-foot, do not even try.
Ditches and berms are easily flattened and there is no simple way to verify their existence. You need to go through the model and see if each high and low area look good.
At the right is a mess that should be a nice retention area.
Streets from contours are a hot mess. That may be fine for a new subdivision road but not for a rehab project or lane additions; those are usually close to grade to start, and you may make a bigger mess doing a quick surface. You need better.
Linking contours with break lines can solve some issues. The problem is they take time to draw and auto functions can make the cleanup harder than just connecting the dots yourself.
In this image the problem is with roadway contours. The triangles will link in a bad way and make a surface that not only looks bad but does not perform. There are no real easy ways out of the issue except to connect them with 3D lines.
Edge of pavement CAD lines can sometimes be elevated as they cross the contours. The straight segments created by the function can cause crossing line and new headaches.
Any of the three lines that make up the road, (edge of pavement, face of curb, and top back of curb) can be drawn and then offset to get things closer. The problem can spike when elevations do not match between contours and 3D lines.
One can argue that it is just a starter file, and this is too much detail. However, this can become a problem when there is not much dirt to move, and crews need more exact information.
3D Lines
Contours have one elevation their entire length. 3D lines vary in elevation and are the best way to create curbs and other road and parking lot features. Files from engineers are usually not loaded with these lines. About the only time I see them are as break lines inserted to contain features that might have been blown over during design. Without any real 3D lines to look at or adjust, you will need to make your own.
Any time I go to the effort of drawing 3D lines, I make sure all the elements I am connecting are correct. Because of this, I only use them to tame bad spots in a quick model and not for beauty. More detail will be added later when we make the actual finished grade model.
After trying not to draw break lines, the field may finally compel you to clean things up a bit to get closer to the real finish.
Building pads benefit from a few quick lines to make a fence around the single elevation.
Retention areas can benefit from a little cleanup by installing lines on corners and bottoms. These are usually the first thing done on a site so that makes sense.
Large sheet graded areas are the first to go as well. They are not too hard to do so you can get a jump on the field by making these look nice while drilling down when building the hard stuff.
The retention to the right looks better with some break lines. It still needs some more and the northwest corner is in the dumpster.
Points
When doing a quick repair on a bad model, points usually never enter the picture. There are times when they will come in handy though.
When you have utilities to install, structure elevations shown as center.
Any existing utilities and bends that can be noted by points can save a mess. 2D or, 3D is better if possible, will come in handy in the field.
If you have control points, include them on the screen as well as a text file to upload to the data collector for an easier calibration.
Surface File
Sometimes you won’t get the pieces used to make up a surface, you just get the triangles. With Civil 3D files opened in that program, the individual parts can be extracted as well as other important data to make the job of the model from the engineers clean up easier. When all you have to work with is a mass of triangles, you do not have a lot of options for greatness.
Trimble Business Center will keep your changes to 3D faces when regenerating a surface.
Carlson will make a new model; preservation of swapped faces is some work. It involves saving your changes and incorporating them into the new model.
Do not be worried about removing faces and adding break lines to an engineer’s surface. Civil 3D has a lot of settings, usually CAD technicians get their finger stuck on the “make a lot of triangles” button.
The surface on the right is not too bad. There are areas that could be improved. This may be okay to start the job but will have to be improved to make the grade.
Here is that same general area as a finished grade model ready to work. Better triangle density and smoother contours on a gut check let us know this will do the job.
An Experiment
I performed a takeoff from an engineer’s surface that consisted of 3D faces against our model. Here are the results:
Important notes
This is a small area at about 3.5 acres and there is a lot happening in a little spot.
There is a couple thousand-yard discrepancy in the dirt numbers.
The max cut and fill is 4-feet each. Their model is considerably different than ours.
Summary
“We need it now” is all too common with the fast-track world we live in. I do not want to see people waiting to deploy technology on a job. I also do not want to see dirt moved twice because somebody got a model that had too many issues. A balance must be struck. It is our job to be sure that what goes out quickly is not going to cause extra work. Be careful and check what you are sending. It is better to have the field complain they have no model than a bunch of rework.
We all want all jobsite data available to us in a grading model. I have always contested that 10 minutes at the computer is about 30 minutes in the field balled up in the truck with a calculator. We do as much as is requested for a job, but we will also not waste your money when it’s not cost effective or better to be done in the field. In this offering, we look at both scenarios to show what a good model and related details can look like.
Demolition
It’s good to have detailed information on the areas of a project that are slated for removal. However, we need to be careful because the quality of the information can cause more problems than cures. The first step is to get the CAD files from the existing conditions and send them to the field for comparison. If the 2D linework is an exact match, it would then be okay to let the work get to the field for demolition. Keep in mind, this only works for what is visible. I try not to trust the sub-surface drawing data and usually exclude it. We have seen too many pipes that do not follow a straight line and are broken when digging.
What to trust? Always be careful when supplying existing conditions to the field
Now that we have a solid trust in the plans for demolition, what is the procedure and deliverables?
2D linework initially goes to the field for verification.
Take point shots to confirm plan views.
3D points will help to update the demolition plans.
Be aware of amounts and locations for demolition. If something is missed, now is the time to document and get a change order started.
Incorporate the 3D shots into your demolition file.
Update the existing utility locations as you go along. They will be part of the as-builts.
Model Basics
There will be some confusion as to what constitutes a model and what is extra and may not be needed. For sites, I have seen just building pads and retention areas. The model builder for the contractor thought it was best to work out the parking lot in the field. When we are asked to do “the usual stuff” for a civil site, here is what you will get:
All pads to requested grade. Some people like finish slab height while others want top of stone base.
Retentions to requested grade. There will sometimes be liners, clay or topsoil added later so we might do a retention subgrade.
Parking lot to finished grade. We use finished grade in the model for two reasons; it’s easy to dial down to subgrade and when you need to reference plans for grades you avoid possible math errors to guess subgrade. It is also easier to offset the parking lot slope to grade 2-feet behind back of curb for a machine to pour.
Curb layout can be lines and/or points at top back of curb as well as offsets. More on that later.
Offsites are a wildcard. If we get grades for deceleration lanes and approaches, we will enter them. Usually, we will want some existing grade shots to confirm. This is important when there is a sawcut and we need to make a lane, gutter, and curb to flow correctly.
Utilities are an option. We provide surface inlets, grates, and manholes but pipe and structures can be added for contractors who self-perform.
With this information the contractor can get a job to the point of completion while working with a surveyor. All information should be available to the engineers, surveyors, and forward-thinking municipalities. We often send out different file types for various programs used by those other than our client.
I usually find that when contractors get comfortable with this technology, they start thinking beyond the basic model. I have always tried to leverage the power we now have. With that, we are always able to improve the use of GPS surveying and related equipment to make things quicker and reduce re-work. The options that follow are a welcome sight to an experienced user. New users will feel like they are drinking from the fire hose. Be cautious when getting new users up to speed. A more basic surface model and less linework can make the process easier.
More Information
I need to caution the reader here. With additional information comes added responsibility. When you leave the basic model and start adding on, this results in extra layers, more surfaces, and various points files. All this needs to be managed and kept current. Before stepping off and getting into these weeds, make sure you have file flow dialed in.
Every surface and linework file must have a date. It makes it easier to identify the most current information is being used.
Use a cloud-based service for field files. Set it to notify involved parties that new files are available. This makes it easy to know when new files arrive. Without this setting, remote workers waste time checking the folders or could potentially use outdated information.
Have one person in the office be responsible for updating. They will also keep the field in touch with changes and next steps.
Additional Surfaces
When doing added work, it’s sometimes easier to just make a new surface. Here are some examples:
A large excavation for a basement or underground parking. We will often build ramps and haul roads for mass excavation. This allows the haul roads to be cleaned on a regular basis for high-speed scrapers. Smooth ramps and roads save beat up machines.
Pad blowups. If there are a lot of sidewalk and grading details near a building, we will build a separate surface for a pad. This red line shows where the 5-foot blowup will go for the building. There are a lot of bump-outs on the slab and it will actually be built as simply as possible. We will make a surface to reflect this. It also provides the contractor with the amount of rock and select fill as they now have the square footage of the enlarged pad area.
Retentions with specific subgrades usually need another surface. The reason is that the final size is critical and often these have steps in the subgrade but need to be smooth for finish.
The job here had a deeper subgrade in the botton than the sides. It would have been difficult to just make a finished grade model or only a subgrade. Always look at the time it takes to do a quick in-progress model as opposed to having to work things out in the field.
Curb Offsets
Whenever we are asked to do curb offsets, there needs to be a clear idea what we are after for production. Here are the options we usually perform.
Additional layout line. This is a Top Back of Curb (TBC) line we add to a model for layout. The offset allows the contractor to know the height of the TBC without having to disturb the actual curb location. This is good for setting stringline and installing hanging forms.
Top Back of Curb (TBC) Surface. We will make an additional surface that represents the TBC elevation and a specified offset. This allows the field to walk (usually 3-feett) wide surface that is the TBC elevation for layout and checking. Always make this a separate surface, otherwise it will make a mess of the grading model if you don’t.
Layout points. We provide 3D so we can layout the curve PC, PT, and radius points. Also provided are points along the straight lines for grade checking and string setup.
There are a lot more things that can be done with a little imagination. Look for more ideas in the upcoming blog articles. We do a lot of specialty work that may help you someday.
