Enhanced Data: Subdivisions

Enhanced Data: Subdivisions

Beyond the surface in a subdivision, there are things you can do to make your job easier. I will cover the more common tools we use to expedite planning in subdivision grading and paving jobs. I will also breakdown the improvements we’ve made beyond the simple site and linework.

Surfaces

Often there are several stages of dirt work within a subdivision. Don’t be afraid to create several surfaces for a site. Similarly, the details of the finished pad elevations, and even lot sizes, are not detailed due to the rush to get something out of the ground.

Starting with an erosion protection plan will establish several retention areas to contain site runoff during construction. These are usually basic and don’t require a lot of detail. Be sure to include any silt fencing and erosion barriers that are required in the initial work.

Streets

You can count on a lot of streets in a residential area. We have performed grading and paving data using many unique details that will help field crews. Here are a few of the models that we make:

Rough Grade Section

A great planning tool for dirt efficiency is a “gut section” model for streets. The idea is to do an over excavation of the streets so the spoils generated for utilities can stay there, and be used to get the road to subgrade in preparation for stone.

The above example shows the street to subgrade, cut straight across, ignoring the crown. We also went to 2-feet behind the curb so the curb machine can get better access. A model is built to street slopes as well so the subgrade and stone are set right.

Curbs

One of the best things to do when establishing curb grades is to give the field extended information for more efficient outcomes. We have been building curb data that helps the field for years. Here are several of the ideas that make things easier for them.

Working with Curbs

Top back of curb (TBC) grades are the base for everything that happens for streets. The sidewalk is set from that elevation to the inside. The grade is used to set string line, or made into an alignment for a guided machine. When done correctly, the street base can be graded with a laser against the top of curb and paved, even with the gutter. The issue with a curb elevation line is it is exactly that, a razor thin line that changes quickly in elevation to the inside and 1.5-2% to the outside. Often times this gives us a slightly incorrect curb elevation that seemed correct but makes for an inconsistent road.

One of the best ways to provide solid TC elevations is to do an offset line, usually about 3-feet behind the back of curb, and make a surface reflecting that.

Here is a cross section showing the finished grade sidewalk section on the right and the flat TBC offset added to the right. A couple notes:

  • The name “Curb OS” appears on the screen because I named the linestring. That’s the reason I use naming for linestrings to verify their inclusion.
  • The sidewalk on the left has a 1.5% slope. The maximum slope for a sidewalk is 2%. We bring that down the half a percent to insure the slope never goes over the max.

The cross section of a curb relates to how things get worked out in a slip formed curb and nothing to do with grading. We will look at what the curb does as it’s placed and what we do with the subgrade.

When we grade a road, the above (in red) is how the surface is made. The cross slope of the road is 2%, and the slope of the gutter in this typical is 6.5%. If we were to respect the gutter slope, the grader would get confused and make a mess of things, as the tip of the blade got close to the grade break.

Keeping the slope at 2% gives a bit of stone for the curb machine to plane as it makes the pouring pass. The difficulty comes in understanding what happens when you dial down to get to subgrade.

In the above diagram I am dialed down to top of native. The subgrade needs to extend out for several reasons:

  • The original ground for the curb is not excavated.
  • There needs to be an offset to provide room for the curb machine.

To make this part of the job easier, be sure the TBC line is continuous so snapping and offsetting for grading is more efficient. When placing stone, be careful to get just enough under the curb to give the curb machine something to grab to but not so much as to waste a lot of material.

When you have made a surface that has the flat TBC area, be sure to include the finished grade surface so the sidewalks and parkway sections are correct.

Lots & Pads

Lot Marking

I have always wanted as much information as possible on a data collector to do my job. When it comes to marking out lots for grading sometimes you can get too much on the screen.

At the very least, you need to have the lot number and pad elevation. Here are some additions that may help in some jobs but can cause clutter if used at the same time:

  • Lot Dimensions are seldom necessary. Where we find them useful is for acre sized lots that are irregular and insure you are not grading somebody else’s property.
  • House layout lines can help to define driveways and lot grading details. They take a lot of memory due to the number of lines and detail. Clients may load and bring this on the screen late in the job.

This image is a good example of what you can put on a screen, and still keep your sanity. You would not have all the layers on at the same time. However, it is good to have grading, streets, and utilities together for convenience or for reference. Before exporting this to the data collector, I might change the lot number color from yellow to another color. It’s difficult to see in the light.

Pad Overbuilds

When you need to add block walls, or larger fences, to stepped pads an overbuild is usually required. This changes several things:

  • The lot line is now not the top or toe of the slope. It is necessary to maintain lot lines on your screen for clarity.
  • Some details call out overbuilds for a block wall then removing material later after it’s in. Watch the grading details closely.

This detail runs for over 50 pads in this subdivision. For this level of detail it is good to create a specific grading file for it.

The overbuild goes into the high lot 2-feet, after the wall goes in the bench and slopes are modeled to get drainage right.

Raking Pads

When a series of lots are vertically separated, usually by .3 feet or less, the grading plan calls for the pads to be sloped from the high pad to low. This is not a problem and makes the work go faster. Lot lines and pad compaction can suffer so be sure to detail these areas with good linework.

Basements

Lookout and walkout basements are an opportunity to use a lot more detail than flat pad sites. We have done everything from excavation pits and laybacks for walls to finished slopes outside the footprint to provide positive drainage between lots.

Each home site is an individual grading plan that has to be reviewed and data prepared properly. When the plan is designed well on the screen, guided excavators can make the basements quickly.

Summary

I have explained some drill down points that will help to improve accuracy in building subdivisions. The accompanying video goes over the information provided plus other details we use to improve the quality of this type of job. Included are some alternate approaches to lot and street design. Staying with design and translating that into practical models that increases efficiency is an ongoing task we take seriously.

Working with Surfaces: Trimble Business Center

Working with Surfaces: Trimble Business Center

“Software tools” is an interesting term. A tool allows you to perform work. Using the wrong tool or trying to put too many in your bag causes problems. The software tool, Trimble Business Center, utilizes commands for creating, editing and checking surfaces to help us make data that performs well in the field. We can do this quicker and more accurately than ever before but I find users get bogged down with what commands to use and when to use them. To complicate things further, as new and enhanced commands come out, users can be confused and frustrated trying to drink from the firehose of improvements.

Today I want to go over some of the commands in TBC and talk about the best places to use them. This offering is not a training on surfaces. You can find videos on that through Trimble’s website. What this blog post will so is focus on some powerful commands that are time savers and life savers for certain situations.

I’ll reinforce some of these ideas with a video to help illustrate these concepts.

Importing a Landxml surface

TBC has some great import options for xml surfaces. Here are some ideas:

  • Never use drag and drop for an xml surface. I like to track the import options for each type of file.
  • You may need to import the surface several different ways to get results you like.
  • Check the file header to verify units are correct.
  • If you are not certain of the quality of the surface, check detail areas for accuracy.

In the import command option, there are several options.

I usually don’t expand the explode options. You have several options should you decide to do so:

Try CAD Points and Lines if you want to break out surface elements. If both are present, you can have them separated to make customizing the surface easier. There is a lot more to xml. I will do an article on that particular subject in the future.

Definition of a surface

We work with a TIN (Triangulated Irregular Network) also called a DTM (Digital Terrain Model). A surface like this consists of flat triangles, often times thousands of them. The TIN produced is the representation of points, 2D, and 3D lines produced in the software during data prep. By using various commands and changing the screen elements that make up a surface, we can make it work better for our purposes.

There are options to adjust the triangles in a surface but I feel it is better to make your screen work reflect the desired outcome.

Tool Review

I want to go over some surface related commands that are either misunderstood or have more depth than meets the eye.

Surface Properties

TBC has a lot of features that seem to lurk in plain sight. The control available in the Properties of a surface is one of them.

Color – Try and set consistent colors for different surface types. It helps when you open an old job.

Horizontal alignment – A quick plan-based road (not a true corridor) greatly benefits from an alignment-based surface. Use it whenever possible.

Edge settings – I will sometimes reduce these to close off errant triangles outside my desired surface before making an edge breakline. These default settings are usually fine.

Adjust flat triangles and tolerance to help reduce flat triangles on the surface generated from imported contours.

Set rebuild method to “By User” when working with large surfaces so it will not recompute with each change.

The visualization settings will help to identify specifics during the data prep process. Experiment with toggling an item off in plan and 3D view.

 

 

 

Breaklines

Any breakline is no more than a linestring that is part of a surface. The breakline command does several things.

  • You can name the breaklines. They can be on a selected layer and also turn up named in section views.
  • They can be placed on a separate layer.
  • Sharpness lets you control how the line is used. Soft for grading areas and sharp for curbs and walls. Sharp and texture boundary is for material sections.

 

 

Drape Objects

This is one of those commands that can have additional benefit after the initial command is executed.

  • The normal attributes for what will become a 3D linestring.
  • Converts a 2D line to 3D by referencing an elevation as it crosses a TIN edge.

 

 

Another advantage of the resulting draped line is that it can be offset in 2D and 3D.

  • Select the draped line, right click and view the Properties.
  • You can change attributes in the Properties view.
  • Offsets can be added to the line as well.

There are times this will come in handy. The video that accompanies this article will give examples.

 

 

Merge Surfaces

The idea of merging surfaces is a simple concept but is sometimes difficult for software to process. Here is an outline:

  • There is a larger “outside surface.”
  • I want to make or insert a surface inside the boundary of that larger surface.
  • The software will trim the outside surface and transition vertically between the two.
  • This is a simplified outline. Play with the command to see how powerful it is.

The issue can be at the intersection of the two surfaces. TBC has improved this process and it performs quite well.

  • Name is the new Surface to make.
  • Surface 1 is the outside.
  • Surface 2 is inside, the new work.
  • A clipping boundary can be added to reduce area and file size.
  • Type of merge lets you select elevation difference or the entire surface.

Sometimes there will be spikes at difficult transitions. Review the resulting surface and make minor corrections as necessary.

 

 

 

Create Surface Tie

This can be used in conjunction with or instead of the merge surface command. The command is more of a design tool and can bring a lot of smaller command pieces to one place. The most common use of the command is to place a new building or house pad to a surface and view the resulting slopes and catch points.

The reference linestring can also be open and the command works well for slopes on the outside of a surface you built as it daylights into the existing ground. I will use this for a quick haul road or simple street in a subdivision.

  • Name the resulting slope and daylight lines.
  • This is the layer they will reside on.
  • This is the surface your new work will tie to.
  • Just drag and click to pick projection line direction.
  • This checkbox will not show slope lines, just daylight.
  • Node distance along new linestrings.
  • Slopes can be ratios, percent, or a sharable slope table.
  • This will make the daylight line rounded or square.
  • You can add this to an existing surface. It will update the surface permanently so be careful. You can also not add to any surface, or best, make a new surface that is a combination of the tie surface and your new work.

 

 

 

 

There are more tools and ideas I will share in upcoming articles. Get comfortable with these commands and their use in your data processing. These commands are a great way to simplify and speed up the data prep process.

Enhanced Data: Civil Sites

Enhanced Data: Civil Sites

A previous article dealt with chasing perfection on civil sites. I would now like to further explain some items that we touched on and others that we use to make a job go smoother.

A “ton of information supplied” approach to creating data for a site takes too much time and confuses a field user that may not be aware of the enhancements you made to their job. Some of our clients use the following ideas at one time or another but not all of them at once. Phasing and machine type need to be considered as well.

There are two important things to consider before deciding to use information above a basic model; the benefit of the data in the field and the cost to produce it. Also confirm the desire and ability of field crews to wisely spend that additional work and money. I can work with two different crews from the same company and get buy in from only one regarding enhanced data. Culture sometimes is not companywide. You need a champion to grab a new idea and leverage it for real success with a new idea.

Begin at the Beginning

We need to establish a point of departure for my ideas. The least you should present to the field is a correct finished surface model showing areas that are going to be worked with a blade. Nothing fancy, but a faithful representation of the intent of the job. I use the word intent with an explanation. It is the intention of all involved to have a good looking well performing site. If the plans don’t reflect it, you are the last line of sanity before something incorrect gets put in the ground.

This basic model is what most companies who do in-house data provide. Office staff are just too fractured to spend too much time on any one job. I know, I’ve been there. When field crews get comfortable with a basic model, they usually want more information to boost productivity.

We will increase data information with a new user of data as their comfort level increases. The real trick is what makes the most impact for boosting productivity.

Enhanced Data Options

I like to produce the most bang for our client’s buck as possible. I will go through these concepts in a video as well. A few minutes of screen time can take the place of hundreds of words.

Linear Features

Lines can be either 2D or 3D. Adding the third dimension may work OK for some data collectors but not machines. A 2D line with a surface reference beneath it seems to do fine in most cases. This saves data prep time. The exception to this will be for a curb alignment in a parking lot. The top of a curb is only 6 inches wide, to the inside of the line the elevation drops quickly to the gutter. We will often provide a top back of curb elevation surface that’s 3 feet wide so the elevation is easy to find.

Layout Items

This broad term represents anything you might usually stake but want to reference at any time.

  • Start with a building pad blowup lines and a surface to the extents. We often provide foundation footing trench information. This is usually bottom of footing with vertical steps and varying widths. Pad footing locations and grid layout lines help with larger projects.
  • I’ll cover utilities in a separate offering, too much to list here. As a useful improvement to have on a machine or data collector, utilities are high on the list. 2D water, gas, and electric go a long way in helping the field plan their trenching. Sloped pipe utilities are best laid out 3D for improved production. Structures are often a mix of 2D and 3D information, more on that in the video.

Subgrades

I often get into lively conversations regarding subgrades. There are only 2 choices when it comes to cutting a subgrade, provide a surface file or dial down. We usually try to provide just a finished surface file for several reasons:

  • Building additional surfaces cost money.
  • When you dial down in a machine and offset a subgrade behind the back of curb the machine does a better job than data prep software, let me explain here and in the video. Parking lots have variable cross slopes, often times changing quickly and greatly. A horizontal offset in a machine correctly projects the slope, it is not easy to do this properly in the office.

Many data collectors and machines show the vertical offset on the screen so you know when you are off finished grade. We also like finished surface files because they match the plans, this makes it easier to check grades against the plans without the potential for bad math.

Hardscape

Often times there are a lot more things you are either responsible for or can just help to move things along. When it comes to hardscape items GPS can help with initial ground setup concerning grading. Often times we include layout items that are usually 2D, but beneficial.

  • Streetlights: parking lot lights can be laid out early so underground electrical can go in.
  • Parking Lots: we provide layout for parking lot striping and special marking. This helps the striping to move along quickly.
  • Playground equipment: layout is critical and setting bases and foundations with technology is a real time saver.

 

Offsites

Turn lanes are often times built during a civil site improvement. When plans were prepared, the topo shows existing pavement elevations. Usually these are not correct as the topo is old or the lane was not shut down and the spots were estimated. Here is how we correct this:

  • The contractor will get quality spot elevations at 10 feet along the proposed saw cut line.
  • We bring the information into the model.
  • Proposed changes are made in the model and sent to the contractor for submittal.
  • Approved updates are sent to the field for work.

These ideas will help define the best enhancements for civil sites. We do a lot more, depending on the job. This is a start on your path to feature rich data and increased profits.

3D Data: More than Machine Control

3D Data: More than Machine Control

For many years, our business has been centered on the production of 3D data for machine control. This is the low hanging fruit of a civil site. High dollar paving, building pads, and retentions are easier to do and higher quality with machine control. Fast forward to current times.

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.

Site Layout

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.

Utilities

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.

 

As-Builts

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.

Chasing Perfection on Civil Sites

Chasing Perfection on Civil Sites

We need to strike a balance between a picture perfect model on the screen and a well-priced practical job that performs well. Nobody wants us or their model builder to make some infinitely detailed model that would be so dense it would slow down machines. Not to worry, I’ll include a video to show you what I’m talking about.

Now to the details.

Parking lots

With the thousands of jobs we work on in any given year, parking lots are by far the most difficult. The reason is that the parameters are very specific but most plans lack sufficient information to accomplish this.

Plans should include:

  • All areas needing to drain correctly.
  • Slopes in common areas which need to support safe walking.
  • Handicapped parking spots requirements for slopes.
  • Grade breaks that will divert water to designed drainage structures.

In the past, the surveyor would blue-top spots from the plans and a grader operator would fulfill the above requirements. Now that we can do it digitally, it is important to check and verify plan intent so the blade operator can go full automatic in the field and get a good surface. When the data is not built correctly, an operator must field fix to make sure the rules are followed.

We are not going to go as far as running rainfall calculations to check engineering. We must however respect flow direction and grade breaks to deliver a smooth surface.

Here’s how:

  • Initially build the surface according to the plans. Fix obvious busts of three tenths or more.
  • Review the performance of the surface. I like to view slope arrows and create contours at a tenth of a foot which makes slope changes obvious and easier to fix.
  • Add breaklines to define the surface.

There is often a lot of time spent with small areas of a parking lot that are not working well. Experience will be the judge as to how much work it takes in order to meet the objective. Sometimes there just needs to be an extreme break over angle or varying slopes where you want a single one.

It is critical to remember how the surface is going to get from the screen to the dirt. A long grader blade is going to be making the undulations you have programmed into the file. Yes, the operator can rotate to make a narrower effective width, but it is important to consider this fact when building data.

Details

There are things we do that to me seem like a great way to increase speed and accuracy, improving margins. Here is a list of some the good and the bad:

  • Handicapped ramps. We can build a great handicapped ramp but I think common sense prevails. Machine curb will be run and the ramp cut out while the mud is still wet. We will give you linework so you know where to put the ramps but leave the curb full height.
  • Curb layout points. PC’s, PT’s, and radius points are a great way to layout hand built sections of islands and driveways. We will usually group the points by type so you can keep screen clutter down.
  • Saw cut line for turn lanes. When we get offsite plans, the existing road elevations may not be correct. Contractors will take good shots of the transition and send them off to us. We will build the entrance and propose changes in elevation where things aren’t right. We will forward that information to the engineers for approval.
  • Surface overbuilds. This is taking the outside edge of a surface three feet or more so equipment does not go out of design and need to reset wasting time. Newer control boxes are not a victim of this. If you are running older equipment then that’s OK. Don’t clutter up the screen with an overbuild if you don’t need it.

The take home message here is that data should look simple. The problem is that it takes a lot of work to make a simple looking surface. Machines and rovers have ten times the power and features than those from ten years ago. Use this to your advantage and leverage feature rich information. Your checkbook will thank you.

Using optical character recognition for data prep

Using optical character recognition for data prep

We have all been there. We come across a lot of numbers that need to be entered during a project. It could be spot elevations, alignment information or control. Life would get easier if we could just get the numbers from the page into our program!

In this post, I will cover two approaches to accomplish the task. Carlson has a solution that is outlined in this video as well as a walk through in the article. One of our talented engineers, Jessica Dugger, let me know about an online service that is reasonable and highly accurate. Her experience was with a raster .pdf and resulted in a highly accurate conversion. Several characters were interpreted incorrectly, but that was an easy search and replace fix in Excel. I will use a vector sheet to show the process in Convertio.

I used Bluebeam to breakout a sheet from a plan set for the demonstration. Nothing special, and this could easily be a table with a thousand points with equally huge coordinates.

Here is the coordinate table I want to convert. Just as a test, I converted the entire sheet with plan and profile as well. It did a great job with the text and actually brought in the plan view areas as a .jpg. This may help as well for an image to send with an inquiry.

The coordinates came in fine. I can now do some quick Excel editing to make it easy for my software to recognize. I will use the letter for the point name and use the full description.

You will notice the flags on the numbers and the Point name “O”. They were text and I converted them to numbers. The “O” was text, I ignored it to keep it that way. The file was then saved as a .csv for use in any software. Here it is in Trimble Business Center:

The foot indicator came in as a question mark, other than that, the import was easy and quick. We use tools like this to improve productivity and give our clients better value by saving time in managing data.

Carlson has a text conversion tool that does a good job. The prior example was really simple but the Carlson tool can come in handy with a lot of pages as it does not cost extra, or require you to be online for the conversion. We use it with jobs that require non-disclosure or are sensitive government work. Here is the process:

• Strip out the sheets to convert
• Bring them into Carlson as Linework

• Open the convert polylines to text command
• Create a new file name for the project
• Populate the characters you want to recognize

• Select and convert text.

Not to worry, I have done a complete screenshot video explaining the process below. The process is slow to set up and sometimes you will need to fix things in Excel doing a search and replace but overall the results will save you a ton of time!

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