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.

Update on LIDAR and Photogrammetry

Update on LIDAR and Photogrammetry

With the New Year well underway, I wanted to take a look and review the advances and advantages of current imaging technology as it relates to creating surfaces from LIDAR and Photogrammetry.

It appears that the more things change, the more they stay the same. Several parts of this world have made great strides while many remain slow to progress.

Drones

UAV platforms are cool, that is unless you have $38,000.00 in the air and it’s not responding to your request to come home. We need this device to do one thing; move a sensor in a predetermined pattern and image when requested and return safely for another use.

Prospective buyers have become focused on flight times, but the real number I always want to know is coverage and quality. A great camera with a proper lens can go high, fly for a short time and get the accuracy we are after. Once you know all the variables, the questions you ask will change.

Multirotors have idled in regard to advancement. Good motors, precision GPS and bigger more efficient batteries have allowed good flight times and safe operation. We use parachutes with our copters and feel comfortable sending them up.

Fixed wing platforms are split into two distinct camps, hand and wheel launch. The small, quick wings cannot carry good cameras and data quality suffers. The larger platforms need wheels and smooth ground but offer the benefit of carrying a larger sensor for better images. There is crossover in these types including hand launch/belly or parachute landing; the blurred line is offering some possibilities.

I am hoping this next platform gets proven soon, I like where it is going. The VTOL (Vertical Take-off and Landing) plane holds promise. Lift like a copter then fly high and fast with a big camera for a long time. Like any other platform, power is always the issue, to remedy this, some makers are putting gas engines to be used as thrust motors and even generators. I think we will have something worthy by year end.

Imaging

At this moment, the best solution for aerial topography is a full-frame sensor camera and a good lens. We can obtain good accuracy on a consistent basis. There are some improvements on the horizon that will help things.

When a drone flight is not possible due to regulatory restrictions, our trade partner Doug Andruik at Syn-Geo had created a two-camera pod he puts on the strut of a Cessna and effectively does close range photogrammetry with a full-scale aircraft. A great solution for large acreage or no drone zones.

We are all waiting until LIDAR becomes effective for use on a UAV. Several versions are out with fair accuracies and high price tags. Development is happening daily because of the great potential of the application. I’ll look at these and report as they become available.

Improving Accuracy

One of the best things to come along for improved close-range photogrammetry is precision GPS. The Applanix chips (Trimble) have made geo-referencing images more accurate and easier. When an image is correctly geo-tagged, post-processing is quicker and the resulting 3D information is more accurate. Combine this exacting geo-tagging and good images and accuracy gets much better. This makes our fieldwork more efficient and the results in the office better. In my opinion, this is the go-to solution; for now.

Processing

Pix 4D is still the easiest post-processing software, my issue is the same data-set run multiple times yields different results and residuals. As with any processing of imaging data, check to many ground control points to verify accuracy. UAS Master from Trimble is a robust application with the ability to fully incorporate precision GPS orientation from the Applanix chip. I use the software on a regular basis but am hesitant about training users. When you know how all the aspects of the program interface you can do some great things. When first learning post-processing, there are too many variables in the software to “just click a few icons” and get a result like in other applications. That Power can be a pain to use sometimes. Rumors are that there will be some easier workflows coming in future versions, I’ll keep you updated.

Wrap-up

Right now the best way to get reliable, consistent data is to fly a full-frame mirrorless camera with a high-quality lens using copter with an Applanix chip and post process in the software of your choice.

Always collect a TON of control/checkpoints so you know how good the results actually are. We earn our money back in the office slowly going over data, cleaning up the point cloud and shipping the client a good surface.

Profitable Implementation of CIM, Civil Integrated Management

Profitable Implementation of CIM, Civil Integrated Management

Proposal for presentation at Site Prep Tech

Marco Cecala, President, Take-off Professionals, Inc.

Summary;

The recent advances in technology for use in civil construction are impressive. The broad appeal of GPS, LIDAR, lasers, total stations and computers have provided the contractor with many opportunities. Contractors have embraced these advances, but not without difficulty during the learning process. Many have made technology a profitable part of their business, while others question the advantages.

This interactive presentation will answer questions and provide a strategy for establishing or streamlining your use of technology.

Equipment

  • Brief overview of current equipment types. GPS, Total Stations, LIDAR and field computers.
  • Best use for each type of technology.
  • What to buy, and when.

Training

  • What training options are available and their differences.
  • How to take full advantage of dealer, manufacturer and independent training.
  • How to identify key staffers for leading the technology push.
  • How to stay current with training as it relates to hardware and software upgrades.

Application

  • What to expect from the technology.
  • Implementation; gradual or all in?
  • Responsibility chain when using technology.
  • How the high tech job site differs from traditional grading.
  • The connected job site, how it can help profitability.

Work Flow

  • How technology changes job dynamics.
  • How electronic data affects a site.
  • How to effectively manage data from the office to the field.
  • Meeting requirements for the use of technology.

Marco Cecala is the President of Take-off Professionals. A Civil engineering consulting firm based in Phoenix, AZ. As the nation’s most experienced and largest firm of their type, they are uniquely qualified to work with contractors and engineers on projects of any size.

Their business involves preparing 3D models for machine control, quantity take-offs, training and consulting.

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