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Closed Traverse: Loop and Link Traverses Explained

Updated · GeoCAD Bridge engineering team · 8 min read

Summary

A closed traverse provides an independent check on its own observations. A loop traverse returns to its starting point, and a link traverse ends on a different known point. Both allow angular and linear misclosure to be computed and adjusted; only the link traverse also checks the scale and orientation of the control.

Definition

Closed traverse: a traverse that starts and ends on points of known position, either the same point (loop) or different points (link).

  • Loop: same start and end
  • Link: different known ends
  • Allows misclosure checks
  • Can be adjusted

Loop traverse

A loop traverse is efficient for site control because it needs only one known point and one reference direction. Angles can be checked against (n − 2)·180°, and coordinates must return to the start. However, a wrong starting azimuth or a scale error in the distance meter rotates or scales the whole loop without creating any misclosure.

Closed traverse A-B-C-DA four-sided closed loop traverse. The computed end point A-prime falls slightly away from the start A; the gap is the linear misclosure. ABCDA′ (computed) Leg 1Leg 2Leg 3Leg 4
Figure 1. In a closed loop the computed coordinates of the last point should equal the start. The small gap A–A′ is the linear misclosure that an adjustment distributes back through the legs.

A link traverse starts on one pair of known points (station and backsight) and ends on another (station and foresight). The closing azimuth and the closing coordinates check orientation, scale and position. This is the preferred geometry for route surveys and for densifying control between GNSS points.

Field checklist

  • Occupy and check the starting control; observe a reference object.
  • Measure each angle on both faces with the number of sets required by the specification.
  • Measure distances in both directions where possible.
  • Record instrument and target heights.
  • Close on known control and check before leaving site.

FAQ

Is a loop traverse enough for control?

For small sites it is common, but it cannot detect a scale or orientation error. Tie into a second control point or GNSS baseline when accuracy matters.

What is the difference between a closed and an open traverse?

A closed traverse ends on known control and can be checked and adjusted; an open traverse ends on an unknown point and cannot.

Tools

Articles

References

  1. Ghilani, C. D. & Wolf, P. R. Elementary Surveying: An Introduction to Geomatics, 15th ed., Pearson, 2018 (traverse computations and adjustments).
  2. Uren, J. & Price, W. F. Surveying for Engineers, 5th ed., Palgrave Macmillan, 2010.

Cite this page

GeoCAD Bridge. “Closed Traverse: Loop and Link Traverses Explained.” GeoCAD Bridge Knowledge Center, updated 2026-10-05. https://www.geocadbridge.com/knowledge/survey-closed-traverse/