6 Items to Clarify Before Conducting Site Surveys with an Optical Total Station

Site surveying is an important task that provides decision-making material for subsequent processes such as building planning, exterior works planning, land development planning, boundary confirmation, and understanding existing structures. Using a total station allows you to efficiently acquire distances and angles, but if you begin organizing conditions only after entering the site, it can lead to missed observations, swapped coordinates, insufficient boundary checks, and re-surveys. Especially in site surveying, it is important not only to have measurement skills but also to prepare in advance where to measure and for what purpose, which standards to use when compiling the data, and which information to retain as deliverables. In this article, from the perspective of field practitioners, we explain six items you should organize before proceeding with site surveying using a total station.

Table of Contents

• Clarify the survey objectives and how the deliverables will be used.

• Organize boundaries and the survey scope in advance

• Decide how to handle reference points and coordinate systems.

• Confirm the installation location and line-of-sight conditions of the total station.

• Align the acquisition policy for existing structures and elevation differences

• Establish rules for on-site records and data organization

• Summary

Clarify the purpose of the survey and how the deliverables will be used

Before conducting a site survey with an electronic total station, the first thing to clarify is the purpose of the survey. Even when you say "site survey" broadly, the required observations differ depending on whether it is to determine existing conditions for a building plan, to perform pre-construction checks for exterior works, to evaluate land development, or to identify structures near the property boundary. If you enter the site with a vague objective, even if you think you have measured as much as you could, you may later find that the measurements you needed were omitted.

For example, in a site survey for considering building placement, the relationships of existing buildings, fences, gateposts, roads, and adjacent structures to the property boundaries are important. For exterior landscaping planning, the interface with the road, on-site slopes, drainage direction, and the locations of existing manholes and side ditches will influence later considerations. When looking ahead to site development and earthworks, it is important not only to record planimetric positions but also to decide at what density to capture elevation differences. Coordinates and elevations obtained with a total station are useful information, but if they do not match the intended purpose, the results can be difficult to use.

When organizing survey objectives, you should also confirm who will use the deliverables. Whether the design team will use them for layout planning, the construction team for setting out positions on site, or the client and stakeholders for explanatory materials will affect the required level of accuracy and the way information is presented. The items to check during observation differ between cases where it is sufficient to compile a current-condition map and cases where the deliverable will be treated later as a construction standard. Sharing the intended use of the deliverables before measuring on site makes it easier to determine the priority of observation points.

Also, in site surveys, simply measuring what is visible can be insufficient. It is important to identify in advance elements related to site use planning, elements related to regulatory and management confirmations, and elements likely to cause obstructions during construction. Level differences near road boundaries, buttress/supporting walls of existing fences, drainage facilities, utility poles and their guy wires, trees, outer corners of existing buildings, and height differences with adjacent land are all pieces of information that can readily affect planning and construction. To observe efficiently with a total station, it is necessary to organize in advance the items to be measured so as not to become confused on site.

Once the purpose is decided, it becomes easier to determine the measurement density. For a rough check of current conditions, the focus is on capturing the main corners and change points, but when conducting detailed site development planning you need to carefully pick up the points where the ground changes and the locations where the slope changes. If the site is large or has significant elevation differences, plan on repositioning the total station and consider which areas to measure and in what order so that fieldwork will run more smoothly.

If preliminary organization is lacking, people on site tend to concentrate solely on the surveying work itself, making it difficult to consider how the deliverables will be used. When converting the data into drawings later, problems can occur such as necessary lines not connecting, the meaning of structures being unclear, or height references being difficult to explain. For site surveys carried out with a total station, clarifying the purpose, the information required, and the intended uses of the deliverables before beginning machine operation is the first step to reducing rework.

Clarify boundaries and survey scope in advance.

In site surveys, particular attention should be paid to clarifying the boundaries and the scope of the survey. Even if observations are made properly with a total station, if it is unclear how far the site is to be treated as the property or which boundary points are being used as reference, the reliability of the deliverables will be reduced. In site surveying, not only measurement techniques but also how information about boundaries is handled is important.

First, check for the presence of boundary markers on site such as boundary posts, stakes, nails, plates, or stone markers. If there are multiple items that could indicate the boundary, record the position of each and carefully assess which documents they correspond to. Do not rely solely on site markings; it is important to cross-check them with existing drawings, cadastral survey maps, layout plans, past survey results, and information from stakeholders. However, the legal determination of boundaries or judgments regarding rights cannot be decided simply by on-site surveying alone. In practice, depending on the purpose of the site survey, it is necessary to distinguish between the area measured as the existing condition and the area where boundary confirmation is required.

When using a total station to survey near a boundary, it is helpful for later verification to record not only the boundary point itself but also the condition of structures along the boundary line. Whether walls or fences are located on the boundary line, set back inside the property, or whether structures on the neighboring parcel are close to it are elements that often cause problems in planning and construction. In particular, for building and exterior work, the wall centerline, the projection of foundations, the top of retaining walls, and the location of drainage channels can be important in relation to the boundary. Rather than measuring only the boundary points and stopping there, it is desirable to record the surrounding site conditions as well.

When defining the surveying scope, surveying only inside the site is not always sufficient. Connections to the road, elevation differences with neighboring land, existing drainage outlets, planned entrance locations, and access routes for construction vehicles—information outside the site boundary—can affect the design. Even if you measure the interior of the site in detail, if you do not know the road-side elevations or the flow of roadside gutters, exterior works and drainage plans may need to be rechecked. Deciding in advance how far beyond the site perimeter to capture existing conditions clarifies the scope of work.

Also, when defining the survey area, you need to confirm where entry is permitted. If there is a possibility of entering neighboring properties, roads, private roads, shared areas, or managed land, obtaining prior permission and performing on-site safety checks are indispensable. A total station can observe from a distance if line of sight is maintained, but there are occasions—such as installing prisms or targets, checking boundary markers, or taking photographic records—when people need to approach. If you begin work without arranging the access conditions, you may end up finishing without having collected the necessary points.

In site surveying, how boundary-related information is represented in the deliverables is also important. Whether it is treated as a confirmed boundary, as the location of boundary markers verified on site, or as a reference position affects how one should interpret the drawings. Coordinates obtained with a total station appear precise as numbers, so there is a tendency for them to be perceived as indicating that the boundary itself has been determined. Therefore, it is important to classify and manage the nature of surveyed points according to the purpose of the survey.

By organizing the boundaries and survey area in advance, you can reduce observation omissions on site and make explanations in later stages easier. To make the most of the electronic total station's performance, don't neglect pre-survey information organization; be sure to compile and confirm the site's extent, surrounding conditions, structures near the boundary, and access conditions.

Decide how to handle reference points and coordinate systems

When conducting site surveys with a total station, it is important to decide in advance how to handle reference points and the coordinate system. No matter how carefully you measure each point on the site, if the reference is ambiguous it will be difficult to explain positional relationships when the drawings are produced later. This is especially indispensable when surveying over multiple days, when another person takes over the work, or when overlaying the data with design or construction drawings.

First, confirm whether you will use existing control points or establish temporary reference points on site. If there are existing survey results or coordinate values, check whether they can be used. When using public control points or known points, organize information on the coordinate system, vertical datum, point names, the condition of the points, and their availability. On the other hand, for understanding existing site conditions or for small-scale exterior work, you may set arbitrary reference points on site and organize everything using a local coordinate system. Even in that case, it is important to record which point was used as the origin and which direction was set as the reference direction so that they can be restored later.

With a total station, the setup of the instrument station and the backsight affects the orientation of the entire survey. If you enter the instrument station coordinates incorrectly, mix up the backsight, or set the azimuth incorrectly, the points measured afterward can all be shifted together. In site surveys, which tend to have a large number of observation points, an initial setup error can lead to major rework later. Before fieldwork, it is important to organize the rules for the instrument station, backsight, reference direction, and point naming so they can be checked at the start of operations.

Also, attention must be paid to the placement of control points. Having control points in locations with a clear view of the entire site makes work efficient, but depending on site conditions it may be impossible to measure the whole area with a single setup. In that case, assuming setups will be relocated, consider where to place additional control points or temporary points. When relocating setups, it is important to secure points that can be observed in common so that observations before and after can be connected. If there are too few control points, it becomes difficult later to verify the consistency of observations. Conversely, if temporary points are increased haphazardly, point naming and management become complicated and can cause confusion during data organization.

Don't forget the elevation reference. In site surveys, not only horizontal positions but also ground elevation, road elevation, side-drain/gutter elevation, the top of retaining walls, and heights around building floors can be important. You need to decide which reference to use for elevations—whether to use an existing elevation datum or an arbitrary temporary benchmark. If you deliver results with the elevation reference unclear, there is a risk of misinterpretation during the design or construction stages. Even when using provisional elevations, clearly state which point was used as the reference and what elevation in meters was assigned to it so that it can be easily confirmed later.

When handling coordinate systems, it is helpful to be mindful of integration with drawing data. If you plan to overlay survey results on design drawings, you need to confirm the orientation in which the site survey deliverables are produced and how they will be aligned with the north direction or street centerlines of existing drawings. Rather than simply plotting the observations obtained with a total station directly onto drawings, it is important to organize them into a form that is easy to use in subsequent processes. If coordinate transformations, rotations, or translations are required, leaving the points that form the basis for those transformations will make later verification easier.

Organizing control points and coordinate systems may seem like a mundane preparation on site. However, if this remains unstable, no matter how many points you measure, the overall reliability of the results will be reduced. Before proceeding with site surveying using a total station, make sure you have established the horizontal position reference, the elevation reference, instrument points and backsight points, your approach to relocating setups, and point-naming management.

Check the installation position and line-of-sight conditions of the total station

In total-station site surveys, the instrument setup location and line-of-sight conditions greatly affect work efficiency and measurement quality. If a site has few obstructions and good visibility, work can proceed relatively smoothly, but on actual sites buildings, walls, trees, vehicles, temporary structures, changes in elevation, and neighboring structures can obstruct the line of sight. If you start looking for setup locations only after arriving on site, not only will the work time be extended, but you may also be unable to measure all the required points.

When planning the setup location, check how much of the site can be observed at one time. A total station requires line of sight from the instrument station to the target point. Boundary points that cannot be seen, the far side of structures, building shadows, and areas behind vegetation must be observed from a different position. If you plan in advance how much to measure from the first setup and what to cover from the next setup, you can reduce movement on site.

In site surveys, it is common to encounter situations where the property is visible from the road but the rear of the site is not, where the boundary areas are not visible from within the site, or where fences and changes in elevation make it difficult to set up prisms. On sites with existing buildings in particular, building corners, exterior wall lines, areas around equipment, narrow walkways alongside the building, and rear passageways can be hard to see. Before setting up the total station, it is important to actually walk the site and identify locations where line of sight is likely to be interrupted.

The footing conditions at the installation site are also important. Check whether the tripod can be set stably, whether the ground will sink, whether it is likely to be affected by pedestrian or vehicular vibrations, and whether people or objects might come into contact with it during work. On paved surfaces, gravel, soft ground, near slopes, narrow passages, and the like, attention must be paid to the stability of the instrument. If the leveling of the total station shifts during work, measurements may be affected. Even after installation, it is important to proceed while checking the leveling condition as necessary.

Visibility conditions can also change depending on the weather and time of day. Strong sunlight, backlighting, rain, fog, darkness, reflections, surrounding traffic, and similar factors can affect surveying operations. In site surveys, because work is carried out while confirming boundary markers and small structures, poor visibility can lead to missed observations. It is important to ensure an environment in which workers can correctly verify the target objects, not just the observations of the total station itself.

When relocating the setup, you need to be aware of the connections between each installation position. To combine points measured from different locations into the same result, it is important to reliably observe common points and reference points and to ensure you can verify their consistency. When working in a hurry on site, it's easy to omit the checks after relocating the setup, but if discrepancies are found later when organizing the data, it becomes difficult to identify the cause. Before and after relocating the setup, carefully check point names, instrument points, backsight points, and common observation points.

The placement of a total station is not simply a matter of choosing a spot with a good view. You need to consider comprehensively the relationship to reference points, the distance to the target being observed, line of sight, ground stability underfoot, safety, workflow, and the ease of repositioning. If you organize site conditions in advance, decisions on the day of surveying will be made more quickly, reducing missed observations and rework.

Align the acquisition policy for existing structures and elevation differences

In site surveys, information about existing structures and elevation differences is as important as boundaries and ground conditions. Using a total station allows you to obtain the position and elevation of individual points, but if you do not decide in advance what to measure and at what density, the deliverables can become difficult to use. In particular, when there are existing buildings, fences, retaining walls, stairs, gutters, manholes, pavement, vegetation, gates, and so on on the site, it is important to prioritize what should be measured.

Existing structures are surveyed in order of priority, starting with those that affect design and construction. Information that often becomes necessary for later drafting includes building corners, exterior wall lines, positions of eaves and projections, foundations and perimeter walkways, ends of walls, gate posts, top and bottom of retaining walls, stair nosings, edges of gutters, and locations of drainage inlets. When taking points with a total station, it is important not just to measure representative points but to record which line or surface each point represents. If only points remain and it is unclear what they were measuring, the results will be difficult to use.

The approach for obtaining elevation differences is another item that should be decided in advance. If the site has a slope, measuring only the lowest and highest points may not reveal changes in between. Drainage slopes, level changes (steps), slope faces, retaining walls, interfaces with roads, and level differences with neighboring properties all have a major impact on planning and construction. In particular, when considering drainage it is important to establish the elevations of the ground surface, the bottoms of side ditches, the tops of catch basins, the road edges, and planned entrances and exits.

When measuring ground elevations, you need to be aware of change points even in areas that appear flat. Observing the four corners of the site, the center, locations where the slope changes, the boundary between pavement and soil, bulges and hollows, and places where rainwater is likely to collect makes it easier to understand the existing conditions. If earthworks or exterior construction are anticipated, it is advisable to confirm in advance the density of elevation measurements required for the plan. Taking measurements too densely will make processing and organizing the data time-consuming, but taking too few measurements can lead to misreading the ground profile.

When measuring existing structures, whether to prioritize plan position or elevation depends on the target. For fences and building corners, plan position is important, but for retaining walls, stairs, and drainage facilities, elevation information is also important. For side ditches, not only the position of the edge but also the flow direction and bottom elevation may be required. If it is a manhole, one may record not only the position but also the type, rim elevation, and, if necessary, the internal condition. Combining points measured with a total station and information supplemented by field notes and photographs increases the usefulness of the deliverables.

Also, when the surveying subject is complex, it is important to standardize point names and how attributes are assigned in advance. If it will be clear later whether a point is a building corner, a fence corner, the pavement edge, or the top of a gutter, drafting and checking will proceed more smoothly. If point names are assigned ad hoc on site, their meaning can become unclear during organization, forcing you to rely on photos and memory. Because the number of points tends to increase in site surveys, rules for managing point names directly affect work quality.

By aligning the acquisition policy for existing structures and elevation differences, you can convert observations from a total station into information that is easy to use for planning and construction. The important thing is not to measure whatever can be measured at the site at random, but to measure with an awareness of the information that will be used for decisions in later processes. By organizing position, elevation, the meaning of the measured objects, and surrounding conditions together, the results of a site survey become more practically useful.

Establish rules for site records and data organization

When conducting a site survey with a total station, you need to plan how to organize the data collected on site. Even if the surveying work itself goes smoothly, if the organization of point names, notes, photos, data formats, and deliverable drawings is insufficient, it will take time to review them later. In site surveys, because there are many survey points and many types of features, the rules for field records affect the quality of the results.

First, it is important to standardize how point names are assigned. Assign clear names for each type of feature—boundary points, control points, building corners, fences, roads, gutters, inlets/manholes, ground elevations—so that you are less likely to get confused when organizing. Even if point names are only sequential numbers, you can organize them if they correspond to field notes and photos, but the more points there are, the harder it becomes to verify. Aim to be able to determine what each measured point is just by looking at the data acquired by the total station.

In site notes, it is helpful to record not only the meaning of survey points but also the conditions at the time of observation. Locations where boundary markers could not be found, places that could not be measured directly due to obstacles, positions measured as reference points, corners of structures that are damaged or missing, and areas with poor visibility due to vegetation are details that are hard to discern from data alone. It is important to leave concise, necessary information so that someone reviewing the results later can understand even if they did not accompany you to the site.

Photographic records are also useful. Coordinates obtained with an optical surveying instrument remain as numerical data, but photos make it easier to confirm the site conditions and the significance of what was measured. Boundary markers, control points, instrument setup locations, backsight points, existing structures, junctions with roads, locations with elevation differences, drainage facilities, etc., should be organized so that photos correspond to the survey points; this will help with drafting and explanations. It is important not only to take photos but also to make sure you can later tell which survey point each photo relates to.

In data organization, raw data collected in the field, processed coordinate data, deliverable maps, photos, and notes should be stored separately in an easily manageable form rather than mixed together. Do not overwrite the data immediately after observation; keeping the original data as the source provides assurance if later verification becomes necessary. When performing coordinate transformations, deleting unnecessary points, renaming points, or similar operations, it is desirable to make it clear at which stage each change was made.

When multiple people work together, it is necessary to decide how information will be shared. It is important to convey the meaning of measurement points, the reference standards, and any points of caution so that the person responsible for preparing drawings and the designers can correctly understand what the on-site personnel measured. In site surveys, information that seems obvious to someone who has seen the site is often unclear to someone who later looks only at the data. Field records are not only to supplement workers’ memories but also serve as materials to ensure a common understanding among all parties involved.

Also, before submitting the deliverables, check for any missed observations or inconsistencies. Review the connectivity of boundary points, the shapes of buildings and fences, the relationship with roads, continuity of elevations, duplicate point names, and the inclusion of unnecessary points. Even if total station measurements were obtained under appropriate conditions, misidentification of points or errors in data organization can reduce the reliability of the resulting drawings. It is important to regard quality control of site surveys as including the processing and organization steps after returning from the field.

If you establish rules for field recording and data management, it becomes easier to recheck site survey results and reduces rework in subsequent processes. To convert data acquired with an electronic total station into deliverables usable in practice, it is important to design observation, recording, organization, and verification as a single, integrated workflow.

Summary

Before proceeding with site surveying using a total station, it is important to organize six items: the survey purpose, boundaries and survey extent, control points and the coordinate system, instrument setup locations and line-of-sight conditions, existing structures and elevation differences, and field records and data management. Site surveying is not simply the task of measuring points on the ground, but the process of preparing information that can be used for subsequent design, construction, verification, and explanation. Proper on-site measurement requires preparation before taking measurements.

The total station is an effective surveying instrument for determining positional relationships within a site based on distances and angles. However, there are many points operators must be aware of, such as ensuring line of sight, setting instrument stations and backsights, managing control points, organizing point names, and preventing missed observations. Especially in site surveys, information such as boundaries, roads, neighboring properties, existing structures, and elevation differences are intricately related, so it is important to prepare in advance to reduce the need for on-site judgment.

In practice, not all conditions will align ideally. Points of caution vary by site—sites with poor visibility, sites with existing buildings, sites with large elevation differences, or sites with many structures near the boundary. Precisely for this reason, confirming the objectives and deliverables before surveying, identifying the necessary information, and establishing rules for reference points and record-keeping leads to consistent results.

In recent years, the practice of managing not only coordinates and elevations but also photographs, point clouds, and positional information in combination has been spreading to make site information easier to understand. If you want to grasp the overall site conditions in three dimensions or make it easier to share information collected on site with stakeholders, it can be effective to consider supplemental measurement methods that suit the purpose and site conditions in addition to conventional observations with a total station. If you want to improve the efficiency of site surveying and make it easier to understand current conditions, be mindful of combining the information obtained with a total station with photographic records, point cloud surveys, and the like, and organizing it into a form that is easy to use in subsequent processes.