California Department of Transportation



Geotechnical Engineering Software


The soil nail wall analysis and design software, Snail, can be downloaded here. External Users must purchase the Snail software license(s) through Caltrans Publications. To purchase the license(s), please send the completed Order Form and signed End User License Agreement to Caltrans Publications via fax.

Snail Download

For External Users For Caltrans Users
Supporting Documents

This software is for stability analysis of soil nails and analysis of structural facing of soil nail walls. This version of Snail replaces the previous version, SnailzWin, of Snail that was first developed and maintained by Caltrans since circa 1989. The software runs under the Windows 7, 8, and 10 operating systems.

Snail implements force limit equilibrium for the stability analysis of soil nails. For structural facing analysis and design, Snail follows the procedure presented in Soil Nail Walls Reference Manual, FHWA-NHI-14-007, FHWA GEC 007, February 2015.

Snail includes the following main features:

  • Options of using Load and Resistance Factor Design (LRFD, GEC No. 7 2015 approach) or Allowable Stress Design (ASD) for both geotechnical soil nails and structural facing analysis and design
  • Performs soil nails analysis using bi-linear or tri-linear search surfaces
  • Performs structural facing analysis with or without soil nails analysis
  • Presents the controlling modes in soil nails analysis
  • Graphically presents the calculated most critical search surface or any user selected search surface, and corresponding factors of safety (FoS) or capacity demand ratios (CDR)
  • Allows parametric study of inter-slice force inclination
  • Allows both U.S customary and metric units
  • Provides graphic and text outputs




Updated 10/08/2018