Why Do I need a Topographic Survey?

Posted by Hogan Land Services on Mar 15, 2017 8:15:00 AM

Topographic surveys are typically a first step in any construction or development project. If you're involved in a project or transaction where a topographic survey is needed, it’s important to educate yourself on the subject. Below we discuss everything you need to know about topographic surveying.

What is a topographic survey?

A topographic survey is done to locate and map all surface features of a property. Specifically, the survey measures and shows the shape, configuration, relief and other applicable three-dimensional characteristics of the earth to create contours. Topographic surveys can also include natural objects such as trees, large rocks, as well as man-made features such as buildings, retaining walls, streets, driveways, landscaping and utility poles. When a topo survey is carried out by a Licensed Land Surveyor the map also includes correct boundary line information that is often needed for setbacks.

Why do you need a topographic survey?

topographic survey topo survey There are many projects and design professionals that make use of topographic surveys, and they are also often a requirement for submittal of permit plans.

The topographic map is often the basis for all subsequent planning and design efforts, and similar to a foundation of a house, if it is not done correctly, it is often more expensive later.  A topographic survey provides accurate information to allow each subsequent step to be done correctly, and on budget.

Many different government agencies require construction and development projects to have topographical surveys as part of the application process. These projects include new homes, major remodels, driveways, road improvements, bridge erection, grading and drainage projects, septic systems, utility design, dam building and more.

Topographic surveys are also used by biologists for environmental restoration projects.

Since topographic surveys are useful in many fields, they serve many purposes. The benefits of a topographic survey vary depending on the type of project. In general, though, topographic surveys:

  • Determine existing conditions and identify any issues with a site or natural area.
  • Show “setbacks” from boundaries or nature features for any new building or development.
  • Provide engineers and architects with the necessary information to create correct and suitable designs for the property's unique features.
  • Indicate how new features, such as grading, building structures, drainage ditches and bridges, can be constructed (if possible).

As you can see, topographic surveys are extremely useful not just for engineers and architects, but also for homeowners, businesses, governments and builders. The information can be valuable in determining if a project can be accomplished. Then, the data collected can show how the project can be accomplished and what obstacles need to be overcome.

Topographic survey methods

Topographic surveys utilize three main methods, and are often a mix of all three as each method has a different strength:

  1. Aerial: UAV Photogrammetry and LIDAR are used to determine the surface contours of large areas, but may not map features.
  2. GPS: Real Time Kinematic (RTK) GPS allows for quick mapping of open areas that are not large enough to justify Aerial methods.
  3. Total Stations: A field crew is on site and directly maps each feature. Utilized when tree cover prevents other technologies, or when the highest levels of accuracy are required.

What influences the cost of a topographic survey?

The estimate for a topographic survey can vary based on several factors. Most influential are the shape and size of the property, the amount of trees and brush, and the accuracy required. Minor influences include accessibility to the site, distance to the site, weather conditions and the format of the delivered map.

For example, surveying a mountainous area in the winter will cost more than surveying flat land during nice weather. Similarly, a wide open field is easier to survey than an overgrown blackberry patch.

Does your Topographic survey require boundaries?

There are many smaller parcels where every square foot matters, and on sites like that, a review of the boundary lines to ensure correct setbacks is especially important.  Many older parcels have never been surveyed and many agencies require a Setback Verification Letter as part of their permit process.  Knowing where to place your dream house is just as important as what it will look like.

For these older parcels that have never been surveyed, only a Licensed Land Surveyor can legally determine and show the boundaries on a topographic map and prepare a Setback Verification Letter.

Getting a topographic survey

If you need a topographic survey, you must know whether the land's features are appropriate for the intended use. Hogan Land Services understands the many different circumstances that may require our clients to get a topographic survey. If you have any questions please connect with us at (707) 544-2104 (Santa Rosa), (831) 425-1617 (Santa Cruz) or complete this contact form to setup a free consultation.

Topics: land surveying