GPS World

Tag: architecture

  • Aligning the trades: GNSS for architecture, engineering and construction

    Aligning the trades: GNSS for architecture, engineering and construction

    Surveyors for architecture, engineering, and construction projects require GNSS receivers that have high accuracy and are rugged enough to survive the dust, water, and inevitable drops that they will endure at construction sites. They also need to be able to easily share data with architects, engineers, planners, and tradespeople, both at the sites and at the office.

    Photo: Juniper Systems
    Photo: Juniper Systems

    Juniper Systems, which has more than 30 years of experience in mapping and data collection in a wide variety of applications across industries, recently released a real time-kinematics (RTK) activation for its Geode GNSS receiver that allows mapping accuracy down to a centimeter. Pairing a Geode with the company’s Uinta mapping and data collection software and a Mesa rugged tablet makes it easy for users to share their data — such as the locations of fiberoptic telecommunication lines or of utility manhole covers — with other people working on site or at the office. The Geode and the Mesa meet IP68 protection certification for water and dust ingress; they also have MIL-STD-810G certification against drops, vibration, and extreme temperatures.

    In this month’s cover image, the Geode is at the top of the survey pole, the Mesa Rugged Tablet is mounted near the user’s hand, and the screen on the Mesa depicts the Uinta mapping software.

    On construction sites, surveying is an ongoing process. Surveyors are the first on the site, before any other work begins, and the last ones there, to map the project “as built.” Total stations with GNSS receivers, as well as tablets and other mobile digital devices are their essential tools, increasingly complemented by unmanned aerial vehicles (UAV) and lidar scanners. Accuracy is their key contribution. In this month’s cover story on GNSS for architecture, engineering, and construction (AEC), we highlight three building projects: a skyscraper in Sweden, a highway in China, and a luxury resort in the Caribbean.

    Check out these perspectives on architecture, engineering and construction:

    ComNav Technology: Building Sweden’s Tallest Tower

    CHCNAV: Expanding a Highway in China

    EOS Positioning Systems: Building a System to Build an Island Resort

  • ComNav Technology: Building Sweden’s Tallest Tower

    ComNav Technology: Building Sweden’s Tallest Tower

    When completed, the Karlatornet will be Sweden’s tallest building and redefine the skyline of the city of Gothenburg, rising to 74 stories and 246 meters (the Burj Khalifa in Dubai, currently the tallest human-made structure, is 828 meters high). Ensuring that the building remains stable even when deformed by very strong winds, sun exposure, seismic activity, settling or shrinkage will require very high precision construction methods. To ensure its vertical alignment, the engineers are using the core wall control survey (CWCS) method, which relies on active GNSS control points, and SinoGNSS T300S high accuracy GNSS receivers.

    A SinoGNSS multi-constellation T300 GNSS receiver and a 360° prism mounted at the top of a building under construction. (Photo: ComNav Technology)
    A SinoGNSS multi-constellation T300 GNSS receiver and a 360° prism mounted at the top of a building under construction. (Photo: ComNav Technology)

    The CWCS method was first used during the construction of the Burj Khalifa and was subsequently applied in the construction of many other high-rise buildings around the world. Swedish surveying company Teodoliten decided to apply this method for the Karlatornet project. Core walls, which are key structural components of high-rises, require a layered construction approach, with multiple concrete pours for each core wall element. CWCS makes it possible to precisely align these core walls with the vertical axis of the building during construction, using GNSS receivers, total stations, inclinometers, and other tools.

    When constructing a tall building, it is essential to continuously measure the positions of various elements at its summit to ensure their vertical alignment. This is typically done by placing at the top of the building four GNSS receivers — referred to in this context as active GNSS control points — each with a 360° prism at the bottom. By sighting the prisms and using the 3D coordinates from the GNSS receivers, a surveyor then sets up a total station. This obviates the need for an extensive array of ground control points, which are often not visible from the top, and for holes in the slabs to accommodate vertical laser plummets. Additionally, observations from a nearby reference station are used to post-process the data from the GNSS receivers in post-processed kinematic (PPK) mode to achieve an accuracy of a few millimeters. The Karlatornet project uses four SinoGNSS multi-constellation T300 GNSS receivers for the active control points.

    It is also necessary to correct for the movement of the survey platform as the building’s main axis is flexed by the loads applied to it during construction. This is achieved by placing a series of high-precision dual-axis inclinometers along the core walls and then applying a least squares adjustment that takes into consideration the floor height of the measuring devices.

    The SinoGNSS T300 receivers operating in GNSS-RTK mode also will be used to monitor and document post-construction building deformations.