How precise point positioning became a survey crew favorite

A positioning service energizes large pipeline surveying projects, saves time, and becomes a field crew favorite

For projects spanning large areas, a large engineering and construction firm discovered that a precise point positioning (PPP) service — Trimble’s CenterPoint RTX — could solve the challenge of receiving high-precision GNSS in remote areas.

Atwell Group LLC is a national consulting, engineering and construction services firm with 33 offices throughout the country and more than 1,000 team members. The company delivers a broad range of strategic and creative solutions to clients in three core markets: oil and gas, power and energy, and real estate and land development.

Atwell provides comprehensive turnkey services, including land and right-of-way support, engineering, land surveying, environmental compliance and permitting, and project and program management.

Photo: Trimble

Pipeline construction

Atwell’s introduction to PPP and Trimble’s CenterPoint RTX took place during two large-scale linear pipeline projects within remote areas. Atwell has substantial experience with projects of this scale, but the remoteness of some of the projects’ sections was proving to be a challenge. While they could expect to rely on base or network correction methods for most projects, Atwell needed to seek other correction alternatives — and up their efficiency for the long-corridor projects.

With the CenterPoint RTX service at hand, Atwell performed construction staking and as-built surveys for a 50-mile pipeline. The project spanned a five-month period, with an hour or more of time saved each day using the service.

Crews noticed an additional benefit: rapid response time. On any given day, there could be project managers, right-of-way agents, or inspectors on site, asking for additional survey data.

“Inspectors and others started to notice how fast our crews could jump from one place to another and get the shots they requested, without having to do any base setups,” said Jason Jung, project manager with Atwell.

“The speed at which our crews can get up and running with RTX is awesome.” — Jason Jung, 3D laser scanning projects manager, Atwell

Because of the range limits of base radios, the crews might have to do multiple setups of a conventional real-time kinematic (RTK) base each day. RTX removed this hindrance, saving the crews time by not having to use temporary RTK bases, which entails driving to base reference points, setup and teardown, and downtime from malfunctioning equipment and battery issues.

“RTX completely freed us from the time and hassle of base setups,” Jung said. “You turn it on, and it’s ready to go before you’ve had time to take a sip of coffee. And once our crews got used to it and gained confidence in the results, they have really loved this solution.”

Photo: Trimble

Scanning a pipeline

Atwell recently used CenterPoint RTX on a 135-mile large-diameter pipeline project that included 19 facilities along the route. Atwell provided as-built services related to the facilities using a Trimble X7 scanner.

The data captured was used to generate spatially correct site models that included the material traceability necessary to comply with Pipeline and Hazardous Materials Safety Administration (PHMSA) regulations. Crews used RTX to georeference point clouds from the scanner to provide the accuracy needed to comply with industry regulations. Each site was referenced with permanent monuments or scribes that tied into the master control system.

Crews also used the RTX service to establish hard checkpoints to meet Atwell’s strenuous quality-control requirements for ground targets, such as those used in UAS control work. To do the daily “in and out” check shots, they used the free BenchMap app to locate nearby survey control marks from the National Geodetic Survey database. Most checks were sub-0.08’.

The time saved in not having to change base positions, as well as setup and breakdown, were significant time savers along this lengthy project. The precisely registered scans helped speed up PHMSA required inspections and audits, and construction change management field operations.

A crew favorite

Atwell’s crews use Trimble R10 receivers and Trimble Access running on TSC7 controllers, but Jung noted that they have recently upgraded to some R12i GNSS receivers, “and they are already earning their keep.” He expects to realize even more benefits from RTX coupled with the advanced multi-constellation capabilities of the Trimble ProPoint RTK engine in the R12i.

RTX has not only become a crew favorite, it is fast becoming a go-to solution for many Atwell projects.