About Amerisurv| Contact    
Magazine | Newsletter    
Flickr Photos | Advertise    
HomeNewsNewsletterAmerisurv DirectoryJobsStoreAuthorsHistoryArchivesBlogVideosEvents
 
advertisement


Subscriptions
Rendezvous
Please Join Us . . .
At Historic Concord, MA
Visit Minuteman Park, Walden Pond, and the Old North Bridge.
Details:
SurveyorsHistoricalSociety.com
Rendezvous
Sponsored By

Software Reviews
Continuing Series
     RTN
An RTN expert provides everything you need to know about network-corrected real-time GNSS observations.
Click Here to begin the series,
or view the Article PDF's Here
76-PageFlip Compilation
of the entire series
Test Yourself

Got Answers?
Test your knowledge with NCEES-level questions.
  Start HERE
Meet the Authors
Check out our fine lineup of writers. Each an expert in his or her field.
Wow Factor
Sponsored By


Product Reviews
Partner Sites

machinecontrolonline 


lbszone.com

GISuser.com

GeoJobs.biz

GeoLearn

 

Spatial Media LLC properties

Associates

ASPRS

newsnow 

Home arrow Archives   The American Surveyor     

Right On Track Print E-mail
Written by Matt Wade   
Saturday, 24 June 2017

A 1.933Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

For its first professional drone deployment, transportation engineering company J.L. Patterson & Associates, Inc. (JLP, now part of Jacobs Engineering Group) surveyed a 30-mile rail corridor with an eBee RTK. Its team reported "phenomenal" data accuracy, completed the job in a quarter of the time of terrestrial surveying, and at half the cost of employing manned aerial services.

The California High-Speed Rail Authority is responsible for planning, designing, building and operating the first high-speed rail system in the United States. Due to be completed by 2029, this transportation project will connect the state's so-called `mega regions', enabling customers to travel from San Francisco to the Los Angeles basin in under three hours at speeds capable of exceeding 200 miles per hour.

In early 2015, the authority selected a consortium of firms to perform environmental and preliminary engineering work for the Burbank-Los Angeles-Anaheim section of the route. As part of this consortium, JL Patterson & Associates (JLP, now part of Jacobs Engineering Group) was tasked with the engineering design work required to support the preparation of the Record of Decision/Notice of Determination (ROD/NOD) with a deadline of December 2017. This means having preliminary engineering work completed by early 2016.

The Challenge
For the Los Angeles to Anaheim corridor, there was zero surveying data available. A host of issues also exist that would make mapping this corridor using ground-based surveying techniques both timeconsuming and problematic.

For starters, the corridor in question--measuring 30 miles (48 km) long by 1,500 feet (457 m) wide--is situated in an active railroad corridor that carries up to 100 trains per day.

"Traditional surveying would have required lengthy permits to access the railroad right-ofway and constant interruptions due to train traffic," explains Marc Cañas, Vice President, National Freight Rail at Jacobs. "The original plan was actually to use conventional aerial mapping, via a manned flight, however the mapping firm wanted eight to ten weeks to fly and process the data. Since our team didn't have the luxury of time, we turned instead to the eBee RTK."

Previous to flying the eBee RTK, JLP had experimented with recreational drones and small scale eBee flights. "We had some very limited experience using the eBee on another railroad project, and a recreational quadcopter, but never with the eBee RTK UAV," says Cañas. "We chose the eBee RTK because it offered the professional quality and survey-grade accuracy we were looking for and it is very compact, making it extremely portable--we can be on site and flying within a matter of minutes, without the need for complicated launching systems. Plus, the safety of the vehicle was important to us, so the software's geofencing feature was a must for our projects. With this eMotion program we could plan our missions ahead of time and execute them with confidence."

Trial, Plan, Execute
Although JLP owns two eBee RTK aircraft, its team was only able to fly one at a time due to FAA regulations.

"We started by conducting several trial and error runs," Cañas explains, "after which we decided to create a series of 1,500 by 5,200 foot flight polygon areas with overlapping areas of approximately 300 feet, which we used to set our set ground control points (GCPs). Our initial trials showed that this approach would fit our corridor objective while allowing us to optimize our time in the field."

JLP's team used the drone's eMotion software to set a 3.6 cm per pixel ground resolution. This figure was chosen to ensure a high-quality ortho aerial while staying below the 400 foot ATO maximum elevation set by the FAA. "We also specified a 69% by 69% image overlap. This yielded enough overlap for our urban environment but still kept flight times within safe battery levels," Cañas adds.

The team's flight planning in eMotion also incorporated elevation data in order to ensure flights remained at a consistent altitude above the ground.

"We used improved SRTM data when planning our missions because we chose to do a series of individual flights and tile them as opposed to merging several flights. We felt this would offer the best results for the change in ground elevation from the beginning to the end of our project limits," Cañas says.

"One of our biggest challenges came from finding suitable takeoff and landing sites," says Cañas. "We would plan the flights in the office and what looked to be great sites ended up being obstructed by overhead wires or street lights, or even buildings that were not in the Google Maps image yet but were there when we arrived to the site. 100% of our project lies within a heavily urban environment. That was challenging in itself. We learned to land in areas that you would never think of, except that necessity drove us to make it work and we did!"

The project's overlapping flight zones contained 82 GCPs in all. Why were these control points used if flying an RTK drone? Marc explains that, "In our environment we couldn't solely rely on the virtual RTK network. There were areas where the RTK would drop out so that posed a problem. Additionally, as far as we and the owner knew, RTK UAV technology had not, at the time, been used this scale and for this type of application, so setting GCPs just gave us extra confidence. As we progress with more and more flights and our virtual RTK network, and we further prove the technology onboard the eBee, I can see these GCPs being eliminated."

The GCPs were painted in place two weeks before the flights took place, controlled using total stations and tied to the CAHSR control network (State Plane coordinate system) the same week as the flights. "Because the entire project is in a heavily urban environment, almost all the GCPs were painted in the streets," Cañas says. "That was a benefit as it made them easy to ID, however it was challenging for the field survey team because they had to work in busy traffic."

To map the 30 mile corridor--an area of 61 square miles--JLP's three drone staff flew 41 flights. These missions captured 11,800 images, with an average flight time of 28 minutes and average flight altitude of 200 feet.

"Each flight's images took our other three staff between two and three hours to process in Pix4Dmapper Pro. After several iterations we found that we could queue up five instances of Pix4D and process simultaneously; any more than that would slow our processing computer down and just prolong the process," Cañas notes.

Talking Results
The efficiency achieved by JLP's first ever large-scale UAV project surpassed its team's expectations. Cañas explains: "We surveyed a dense urban corridor in less than a month. Had we used traditional surveying techniques this would have taken 18 weeks, more than four times as long, and had we used manned aircraft the cost would have been double."

Not to mention that the quality and accuracy of the data JLP produced was, as Cañas says, "phenomenal". "We were able to collect ortho-rectified images at one and a half inches [3.8 cm] per pixel--twice the resolution of even the best manned aerial product--and the data models we produced show accuracies of down to one to two inches [2.5 ­ 5 cm] for both vertical and horizontal--the kind of accuracies you can only dream of with conventional aerial methods."

Michelle Boehm, the Southern California Director of High Speed Rail, echoed Cañas' satisfaction in an interview with a local television station. "Ours is a project for the 21st century, employing 21st century technology, so we want to make sure that we do everything better, faster and more economically. We needed to obtain detailed mapping of our corridor, in quick time, and the eBee provided that for us."

Since mapping its first rail corridor, JLP has put its eBee RTKs to work on a range of subsequent projects, achieving similarly impressive outcomes. "For example, we've flown two rail yards for CSX Railroad and five miles of coastal right-of-way for Southern California's Commuter Rail System," Cañas reports. "All these projects yielded the accuracy we were looking for and for a fraction of the cost of employing traditional methods."

Matt Wade has been writing about emerging technology for more than 15 years. In his current role as marketing director of senseFly, a Swiss commercial drone manufacturer, one of his many responsibilities includes getting to know senseFly customers and helping them tell their project stories.

Sidebar:
Project Workflow

• Identify corridor using Google Maps
• Establish flight model boundaries
• Plan GCP locations
• Submit flight plans & project boundaries to land owner for approval
• Place GCPs
• Contact local ATC/tower to coordinate flights within controlled airspace
Fly eBee RTK at critical locations first (near airports & other controlled airspace)
• Sequentially fly planned limits
• Process data in Pix4Dmapper Pro at end of each flight day
• Create DTM from Pix4D .las file using TopoDOT, MicroStation & Bentley InRail software
• Deliver DTM & orthophoto to client

A 1.933Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

 
< Prev   Next >

 American Surveyor Recent Articles
Editorial 
Thought Leader: Land is Too Important to Be Left to Land Specialists
A while back I was searching the Internet for an old treatise on land titles. A Google query yielded a book published in 1914. The author was Charles Claudius Kagey and the book was titled "Land Survey and Land Titles, a book for boys and girls, a reference volume for property owners, a text ....
Read the Article
Jason E. Foose, PS 
Decided Guidance: Wacker vs. Price - Irony in Sevenfold
This month's case takes us to Phoenix, Arizona in 1950. The Arizona Supreme Court went all guns-a-blazin' in Wacker vs. Price (216 P.2d 707 (Ariz. 1950)). Maybe it's just me, but I'm sensing plenty of irony and have taken license to point it out along the way. I like what the Court did with this case ....
Read the Article
Allen E. Cheves 
Around the Bend - A Visit to Carlson Software
The Ohio River is one of America's greatest, running near 1,000 miles between Pittsburgh and the Mighty Mississippi. Much of the coal and other products that fueled our nation's industrial expansion flowed between the shores of this maritime ....
Read the Article
Lee Lovell, PS 
Surveying & Mapping Economics Part 3 - Customers & Services
This article continues an inquiry into the economic conditions of the Surveying and Mapping industry (NAICS 541370) using data from the U.S. Census Bureau. This time we will look at customers and services. The data comes from the Economic Census conducted every 5 years on American ....
Read the Article
Jerry Penry, PS 
True Elevation: Black Elk Peak
Black Elk Peak, located in the Black Hills region of South Dakota, is the state's highest natural point. It is frequently referred to as the highest summit in the United States east of the Rocky Mountains. Two other peaks, Guadalupe Peak in Texas and ....
Read the Article
Larry Trojak 
Bringing The Goods - Mobile Scanning an Integral Component
When Jim Smith, Jerrad Burns and Charlie Patton left the Memphis division of a major construction company in 2015, they took with them the knowledge of how to get even the most complex jobs done and what equipment could best serve them in making that happen. So when they joined West ....
Read the Article
 
Lee Lovell, PS 
Test Yourself 41: Integers, Integers, and Integers
ABF is a 5:12:13 triangle, ACF is a 48:55:73 triangle, ADF is a 3:4:5 triangle, and AEF is a 7:24:25 triangle, all with integer sides and inscribed in a semi-circle. What are the lengths of BC, CD, and DE? ....
Read the Article
Wendy Lathrop, PS, CFM 
Vantage Point: Sunset or Sunrise?
While we often think of legislated government programs as static, they do change over time. Such evolution and opportunity for transformation are part of the dialogue in reauthorizing these programs. Every so many years there is a sunset on each government program, and this September is the ....
Read the Article
 

deliciousrssnewsletterlinkedinfacebooktwitter

Amerisurv Exclusive Online-only Article ticker
Featured Amerisurv Events
List Your Event Here
please
contact Amerisurv


Google
 
AMERISURV TOP NEWS

GeoSLAM
Engineering Predictions

GOT NEWS? Send To
press [at] amerisurv.com
INTERGEO TV
Online Internet Content

Sponsor


News Feeds

 
Subscribe to Amerisurv news & updates via RSS or get our Feedburn
xml feed

Need Help? See this RSS Tutorial

Historic Maps
Careers

post a job
Reach our audience of Professional land surveyors and Geo-Technology professionals with your GeoJobs career ad. Feel free to contact us if you need additional information.

 

Social Bookmarks

Amerisurv on Facebook 

Amerisurv LinkedIn Group 

Amerisurv Flickr Photos 

Amerisurv videos on YouTube 

twitter

 




The American Surveyor © All rights reserved / Privacy Statement
Spatial Media LLC
905 W 7th St #331
Frederick MD 21701
301-620-0784
301-695-1538 - fax