A Strong Ally for Winter Inspections! Searching for Reference Points Hidden by Snow Using Coordinate Guidance

Table of Contents

• Introduction

• Challenges in Winter Inspections: Reference Points Buried in Snow

• What Is Coordinate Guidance? A New Approach That Excels on Snow

• Principles and Workflow of Coordinate Guidance - 1. Pre-registering Reference Point Coordinates - 2. Starting Coordinate Guidance on Site - 3. Visualizing the Target Location with Camera AR - 4. Locating the Reference Point and Saving Inspection Records

• Comparison with Traditional Methods: Improved Efficiency, Safety, and Labor Reduction

• Improving Accuracy with Localization and Handling Coordinate Systems

• Digitizing and Utilizing Inspection Records

• Winter Inspections Anyone Can Do with a Smartphone and LRTK

• Conclusion: The Innovation Coordinate Guidance Brings to Winter Inspections

• FAQ

Introduction

In harsh winter fieldwork, finding survey stakes, boundary markers, and other structural reference points on bridges and similar structures that have been buried and rendered invisible by snow is a major challenge for surveyors and infrastructure personnel. During snow seasons, inspections of roads, bridges, water and sewer systems, and power lines frequently encounter reference points that cannot be visually identified because they are covered by snow. Traditionally, workers had no choice but to rely on intuition and experience to dig through the snow, probing around with thoughts like "it should be here…" However, this often leads to digging in the wrong place or repeatedly re-digging and losing time. In cold regions, blizzard conditions and ice increase the risk of slips, falls, and accidents, placing a heavy burden on workers.

This article focuses on a new method that addresses these winter inspection problems: "coordinate guidance." With coordinate guidance, it is possible to pinpoint reference points hidden under snow. We will explain its principles and practical use on site, and explore the benefits in efficiency, safety, and reduced manpower compared with traditional methods. We will also introduce the importance of localization (aligning to the local coordinate system) that supports high-accuracy positioning, and how digitizing inspection records improves operational efficiency. By combining a smartphone with a high-precision GNSS, solutions such as LRTK are making it increasingly feasible for anyone to perform winter inspections easily.

Challenges in Winter Inspections: Reference Points Buried in Snow

In winter infrastructure inspections, accumulated snow can completely obscure surface markers, posing a significant obstacle. For example, survey stakes installed along roadsides, boundary stones marking land plots, and reference point plates embedded in structures like bridges become unidentifiable when covered by snow. Traditional methods to find these have included workers probing and digging over wide areas with shovels or using metal detectors to sense metal plates on boundary markers. However, these methods heavily depend on experience and intuition and require considerable time and effort to search large areas.

In regions with heavy snowfall, digging through deep snow is arduous manual labor. If the assumed location is wrong, unnecessary excavation exhausts personnel and wastes time. In low-light conditions such as early morning or evening, visual cues are harder to see, increasing the risk of unintentionally damaging other structures or buried utilities. Furthermore, working on frozen, slippery surfaces or inadequately cleared slopes increases the safety risks for workers.

Thus, the long-standing question has been, "How can we efficiently and safely find reference points that are invisible under snow?" Coordinate guidance answers this. If you know the precise coordinates of a reference point, coordinate guidance can electronically navigate you to that location, freeing you from the trial-and-error, intuition-driven searches. The next section explains the basic concept and mechanism of coordinate guidance.

What Is Coordinate Guidance? A New Approach That Excels on Snow

As the name implies, coordinate guidance is a technique that navigates people or machines to a pre-determined target location using its coordinates (latitude, longitude, and height). Think of it as a site-specific car navigation system. Whereas a car nav leads a driver to a destination, coordinate guidance provides the user’s device with the real-time direction and distance to the target reference point, allowing you to reach the target even across a snowy field without getting lost.

The basic principle of coordinate guidance is simple. When you input or select the coordinates of the reference point you want to find into a device (such as a smartphone), the device displays the bearing (which direction to go) and the distance remaining to that reference point. The worker simply walks in the direction indicated by the on-screen arrow and can instantly tell whether they are getting closer or farther from the target. When far away, the device shows an approximate direction and distance; as you approach, it switches to finer directional and distance guidance. When you arrive directly above the reference point, the system notifies you or displays a marker that clearly indicates "this is the target location."

Unlike traditional methods of cross-referencing paper survey maps and tape measures, coordinate guidance lets anyone reach the exact location intuitively. Its advantages are especially pronounced in environments where snow obscures ground features, as the digital arrows and numerical readouts become the primary cues. However, practical coordinate guidance requires high positioning accuracy. Ordinary smartphone GPS accuracy (on the order of several meters) makes it difficult to dig out a single buried stake. The technology that enables centimeter-level positioning is RTK-GNSS (Real-Time Kinematic positioning). In recent years, solutions like LRTK, which combine smartphones with small, high-precision GNSS receivers, have emerged to provide cm level accuracy (half-inch accuracy) easily. With LRTK, a smartphone becomes a high-precision coordinate guidance tool capable of navigating to reference points hidden under snow.

Principles and Workflow of Coordinate Guidance

Let’s look at the actual workflow for using coordinate guidance to locate and inspect reference points on site. Using a smartphone and an RTK-GNSS receiver as an example LRTK system, the process can be divided into four steps.

**1. Pre-registering Reference Point Coordinates**

As preparation, register the coordinate data for the reference points or stakes you want to find. For roads and structures to be inspected, there should already be surveyed reference point coordinates or positional information from design drawings. Input these into a dedicated app or cloud system in advance. For example, LRTK cloud services allow you to manage a list of points with names or IDs and coordinate values (X/Y/Z or latitude/longitude). On the inspection day, simply select the desired point on the smartphone app and that coordinate becomes the navigation target. Completing this registration as part of your pre-departure data preparation for winter inspections is key to success.

**2. Starting Coordinate Guidance on Site**

Once you arrive on site, begin the coordinate-guided search. When you select the reference point in the smartphone app, the screen displays a compass (arrow indicating direction) and the straight-line distance to the target prominently. For example, it might indicate "northeast 5.3 m (17.4 ft)", updating direction and remaining distance in real time. The worker walks slowly in the direction shown on the smartphone screen. Because the high-precision GNSS continuously measures your current position, the remaining distance decreases noticeably every few steps. Even on a featureless snowy plain, the on-device arrow becomes a reliable guide.

As you get close to the target, the guidance display automatically switches to a precision mode. For example, when the remaining distance drops below about 1 m (3.3 ft), it begins giving fine-grained prompts such as "20 cm (7.9 in) to go," "10 cm (3.9 in) to go…" with audible guidance, guiding you down to the last few centimeters. When the on-screen marker exactly overlaps your position, that location is directly above the reference point. The app notifies you of arrival so you can confidently begin digging.

**3. Visualizing the Target Location with Camera AR**

Modern coordinate guidance systems combine AR (augmented reality) displays with directional arrows to provide visual support. For example, in the LRTK app, when you approach the target coordinates and look around through the smartphone camera, a virtual marker appears in the real scenery. A colored virtual stake (AR marker) seemingly stands on a point of the snow surface, giving an intuitive sense of "this is where the stake should be." Even on completely featureless ground or in a snowstorm with poor visibility, the screen clearly indicates "dig here!" so you won’t miss the spot.

This camera AR feature also contributes to safety. If it is dangerous to approach the point directly on a steep slope, you can confirm the location from a safe distance by pointing the camera toward the target direction and verifying the AR marker. At night or in dim conditions, the marker can appear illuminated on the screen, making it more reliable than searching with a flashlight. By overlaying digital information onto the site view, workers can confirm positions without relying solely on numerical data. This visualization of buried reference points enhances reassurance and the certainty of on-site operations.

**4. Locating the Reference Point and Saving Inspection Records**

Following coordinate guidance and AR cues to dig in the snow will likely reveal the stake or marker. Once you find the target, record its condition. Taking photos with the smartphone automatically attaches the location coordinates and timestamp to the images and saves them. A photo showing that the stake is in the correct location serves as solid evidence for later reports. Systems like LRTK can immediately save and share each point’s measured coordinates, photos, and notes to the cloud, streamlining reporting within inspection teams and to managers.

If you find anomalies at the discovered reference point (e.g., a leaning stake or a damaged boundary marker), you can log those details directly into the app. These data accumulate chronologically, making future inspections easy to compare with previous records. For bridge supports and slope monitoring points, it is crucial to observe and record at the exact same reference points consistently; coordinate guidance enables different personnel to measure at precisely the same locations. The collected digital records can be output as forms or visualized on GIS maps, allowing broader utilization. Compared to the traditional mix of paper and camera notes, centralized data management dramatically improves operational efficiency.

Comparison with Traditional Methods: Improved Efficiency, Safety, and Labor Reduction

Let’s summarize the effects of using coordinate guidance for finding reference points compared with traditional methods.

First, in terms of efficiency, significant time savings are realized. Previously, workers might dig randomly over large areas or thoroughly sweep with metal detectors, often consuming long hours before finding a single point. Coordinate guidance leads workers straight to registered coordinates via the shortest route, drastically reducing discovery time. Field reports note that time spent finding stakes under snow has been reduced to a fraction of what it used to take and that wandering around large sites due to incorrect assumptions has been eliminated. Increased efficiency naturally reduces worker fatigue and frees resources for other tasks.

Safety improvements are also notable. On snow-covered sites, minimizing unnecessary excavation is preferable. Coordinate guidance reduces the need for extensive digging, lowering the risk of damaging buried utilities or surrounding structures. Digital navigation guides workers even in poor visibility, reducing attempts to visually locate points that could push them into dangerous areas. AR displays allow confirmation from a distance, enabling avoidance of hazards near cornices or steep slopes. In some cases where two-person teams were previously required for safety, coordinate guidance can allow single-person operations while maintaining safety, thus minimizing personnel assigned to watch duties.

Coordinate guidance also greatly aids labor-saving and skill transfer. Finding buried stakes used to rely heavily on veteran intuition, and the task became much harder when experienced staff were unavailable. Training young staff took time. With coordinate guidance, workers with limited expertise can achieve consistent results through an intuitive interface, making it easier for anyone to deliver the same outcome. Following on-screen instructions, even newcomers can find reference points with the same accuracy as veterans. This reduces the cost of skill transfer and helps achieve more efficient staffing—an element of workstyle reform.

In short, coordinate guidance offers the threefold benefits of "fast, safe, and simple." It dramatically streamlines snow-affected inspection work, reduces errors and accident risk, and enables operation with fewer personnel—making it an invaluable ally for winter inspections.

Improving Accuracy with Localization and Handling Coordinate Systems

One more point to keep in mind for reliable on-site use of coordinate guidance is localization—the process of aligning GNSS-derived coordinates with the site’s coordinate system. Simply put, localization corrects discrepancies between world geodetic coordinates measured by high-precision GNSS (e.g., WGS84) and the planar coordinate systems or local coordinate systems used in civil engineering and construction.

For example, reference point coordinates used in roadworks or bridge inspections are often managed in the national surveying plane coordinate system or in project-specific local coordinate systems. Without adjustment, GNSS-derived positions can differ from these by tens of centimeters to meters. If the coordinate guidance indicates "here" but that point is offset from the design drawing’s reference point, the result is meaningless. To prevent this, localization calibrates the positioning system using known points on site.

Specifically, observe several known reference points on site with an RTK-GNSS receiver and calculate the differences between their known coordinates and GNSS-observed coordinates. Apply correction parameters to the GNSS system so that, for that site, GNSS results match the local coordinate system (applying horizontal translations, vertical shifts, and, if needed, rotation corrections). With LRTK, carrying out localization by observing and inputting one or two known points in the app initially ensures that all subsequent guided coordinates match the site coordinate system.

Proper localization enables you to find stakes and markers under snow with positional errors on the order of a few centimeters. Skipping this step can lead to situations where GNSS indicates a location that is, in reality, tens of centimeters away. Although localization is a critical process affecting survey and ICT construction accuracy, the procedure itself is not difficult. Once localization is set, subsequent guidance is fully automated and accurate, allowing you to focus on site tasks. When using coordinate guidance, always be aware whether the coordinates you’re using match the coordinate system of design drawings and site maps.

Digitizing and Utilizing Inspection Records

Coordinate guidance not only aids in locating reference points but also brings major advantages in digitizing inspection records. As mentioned, coordinate guidance systems can save the measured coordinates and photos taken at the moment of point arrival to the cloud. This means the data collected on site can be directly used as electronic forms or reports.

For example, during a routine bridge inspection you might measure the settlement of a reference point on a pier. Using LRTK to reach that point, you can then perform leveling or use instruments to measure settlement and enter the values into the app. The digital inspection form immediately reflects those numbers. Photos taken at the same time are stamped with date/time and coordinates, providing highly reliable records and eliminating the need to transcribe notes or later label photos.

Because data are shared via the cloud, there is no need to transfer photo data by USB or send reports by email from the field to the office. Stakeholders can monitor inspection progress in real time and issue additional instructions promptly if problems are found. As historical inspection results accumulate, it becomes easy to compare with previous years on the system, supporting early detection of anomalies.

Compared with analog inspections that rely on paper and manual information transfer, digitized records reduce mistakes and streamline workflows. Coordinate guidance is not just a convenient tool for finding stakes; it has the potential to transform information management and reporting processes around those tasks. The valuable data obtained in harsh snowy conditions should be reliably managed and utilized in digital form.

Winter Inspections Anyone Can Do with a Smartphone and LRTK

Hearing "coordinate guidance" might conjure images of advanced, complicated technology or bulky equipment, but in reality it’s an easy-to-use solution requiring only a smartphone and a small GNSS receiver. Smartphone-compatible high-precision positioning systems like LRTK have low barriers to introduction and are attractive for small teams and regional operators.

From an equipment perspective, initial investment costs are lower compared with traditional optical survey instruments or large GPS units. You can start operating simply by attaching a receiver to a smartphone and subscribing to the service—no need to purchase dedicated survey instruments or deploy highly skilled operators. With waterproof and cold-resistant cases and spare batteries prepared for cold climates, the system will operate reliably even in the depths of winter.

Operationally, simple interfaces and intuitive guidance mean non-specialists can learn quickly. Field reports from LRTK adopters include comments like "We could use it the same day after a short explanation" and "Staff without surveying experience could locate stakes and confirm reference points without difficulty." Younger workers accustomed to smartphones, as well as veteran workers familiar with mobile devices, can use the system comfortably. As a result, tasks that previously required a surveyor can increasingly be completed in-house, allowing inspections to proceed smoothly even with limited personnel.

Notably, technology now helps cover for human judgment errors. Searching for buried reference points once required experienced personnel, but coordinate guidance standardizes the process so that "anyone can accurately navigate" with the tool. This reduces dependence on individual skills and enables consistent work quality. Even in harsh winter conditions, a smartphone in hand can reliably produce results. Coordinate guidance using LRTK is a dependable ally not only for large corporations but also for small contractors, municipal staff, and individual inspectors.

Conclusion: The Innovation Coordinate Guidance Brings to Winter Inspections

In winter inspection sites where snow obscures the view, coordinate guidance is a revolutionary solution. The ability to reliably locate reference points hidden under snow dramatically improves work efficiency, significantly reduces unnecessary digging and travel, enhances on-site safety, and enables inspections with fewer personnel—helping to address labor shortages and support workstyle reform.

The core technologies are high-precision GNSS and intuitive smartphone apps that provide straightforward navigation. Using systems like LRTK, even less-experienced technicians can reach inspection points with the same accuracy as veterans, realizing "surveying and inspection anyone can do." AR displays visualize reference point positions in the real world, helping workers identify buried objects with confidence.

Moreover, because site data are recorded digitally, inspection results can be accumulated and shared seamlessly. Data collected during winter inspections become valuable assets for spring repair planning and preparation for the next winter. Coordinate guidance ensures you can collect that data completely and accurately.

Finally, it is important to stress that these advanced technologies are not reserved for a few specialists; they are tools accessible to everyone working on site. If anyone can stand on a snowy plain with just a smartphone and reach a reference point without getting lost, winter infrastructure inspections need no longer be daunting. Consider adopting coordinate guidance in your operations and let it be a strong ally for winter inspections.

FAQ

Q1. Is coordinate guidance really effective for finding reference points buried in snow? A. Yes. If you have accurate coordinates for the reference point, coordinate guidance can pinpoint that location under snow. Like a car navigation system, it tells you the direction and distance to travel, eliminating the need to dig randomly over a wide area. Field use of coordinate guidance has markedly reduced the time required to find stakes in snow.

Q2. What equipment and preparations are required to use coordinate guidance? A. Essentially, a high-precision GNSS receiver and a smartphone are sufficient. Specifically, use an RTK-capable GNSS receiver (an external compact antenna) connected to the smartphone and a dedicated guidance app. Prepare the coordinate data for the points you want to find and register them in the app beforehand. Also, ensure a communication environment (SIM card or pocket Wi‑Fi) to receive high-precision correction data over the Internet.

Q3. Can I use the built-in GPS in a regular smartphone instead? A. Unfortunately, the accuracy of typical smartphone-built-in GPS (on the order of several meters) makes it difficult to reliably dig out a single buried stake. A meter-level error can easily lead you to dig in a completely different spot. Centimeter-level accuracy is necessary in many cases, so RTK-GNSS is the practical choice. Recently, affordable RTK receivers that pair with smartphones have become available and are recommended.

Q4. What is LRTK? A. LRTK is one type of high-precision positioning solution for smartphones. By attaching a small RTK-GNSS receiver to a phone and using a dedicated app and cloud service, it achieves real-time cm level accuracy (half-inch accuracy). LRTK typically offers integrated functions such as coordinate guidance, AR display, and cloud sharing of positioning data, enabling surveying and inspection tasks to be completed with a smartphone.

Q5. In what situations is AR display useful? A. AR is useful for intuitively recognizing the target location once you’re near it. Even in snow-covered areas with no visible markers, a virtual stake displayed through the phone camera shows "this is where the stake is," so you can immediately identify the point to dig. AR is also helpful in low-light conditions or when you cannot approach the target directly for safety reasons, as you can confirm the location from a distance.

Q6. Will coordinate guidance actually improve work efficiency? A. Yes, significantly. Previously, finding buried reference points relied on experienced intuition and repetitive work. Coordinate guidance directs you along the shortest route to the target, eliminating wasted effort. Depending on the case, work time has been reduced to less than half of what it used to be. Efficiency gains reduce worker burden and free time for other tasks, improving overall productivity on site.

Q7. Is localization absolutely required? A. Localization is recommended if you need accuracy. Aligning GNSS positioning with design or existing survey coordinates minimizes guidance errors. Localization simply involves measuring a few known points and computing corrections, so it is not very time-consuming. Once set, all guided results are corrected to the local coordinate system. If localization is skipped, errors of tens of centimeters may occur, undermining the goal of precisely locating stakes.

Q8. Are the devices affected by bad weather or cold? A. GNSS can usually provide stable positioning in light snow or rain, but severe blizzards may destabilize satellite signal reception. However, such low-visibility conditions are precisely when coordinate guidance yields the most benefit. On the hardware side, using waterproof GNSS receivers and cold-rated smartphone cases reduces failure risk. Batteries drain faster in cold climates, so carry spare power supplies.

Q9. Is coordinate guidance useful outside winter? A. Absolutely. It’s effective not only for snow but also for finding reference points hidden by vegetation, performing nighttime stake installation, or re-establishing survey points after disasters. Whenever you need to accurately locate non-visible points, coordinate guidance is applicable. It is a year-round tool to improve site efficiency and reliability.

Q10. I’m worried about adopting this—can our team really use it on site? A. Initial concerns are understandable, but operation is completed via a smartphone app, so no complex settings or specialized knowledge are required. With basic training at introduction, you can begin using it on site the same day. You can also start with a small pilot and expand use gradually. Many field reports say "it was easier than expected," so rest assured. Advanced technologies exist to support fieldwork—please consider adopting them positively.