@bedrock-engineer/gef-parser

A TypeScript library for parsing GEF (Geotechnical Exchange Format) files. GEF is the standard file format for exchanging geotechnical data in the Netherlands and Belgium, including Cone Penetration Test (CPT) measurements and borehole logs.

This parser handles the GEF format specification, coordinate transformations, and provides typed data structures for analysis and visualization. It uses the WebAssembly build of gef-file-to-map for initial tokenization, with all CSV parsing, header validation, and domain logic implemented in TypeScript using zod.

Try the live demo | View example usage

Features

• Parse GEF-CPT (Cone Penetration Test) files
• Parse GEF-BORE (Borehole) files with soil layers and specimens
• Automatic GEF type detection
• Support for Dutch (BRO/VOTB) and Belgian (DOV) extensions
• Coordinate system conversion to WGS84
• Depth correction for inclinometer data
• Full TypeScript support with type definitions

GEF-DISS and GEF-SIEVE are not supported.

Installation

npm install @bedrock-engineer/gef-parser

Usage

Basic Parsing

Parse a GEF file and automatically detect whether it's CPT or borehole data:

import { parseGefFile } from "@bedrock-engineer/gef-parser";

// From a browser file input
const fileInput = document.querySelector('input[type="file"]');

fileInput.addEventListener("change", async (e) => {
  const file = e.target.files[0];
  const gefData = await parseGefFile(file);

  if (gefData.type === "cpt") {
    // CPT data with measurements
    console.log("Cone resistance:", gefData.data.qc);
    console.log("Depth:", gefData.data.depth);
    console.log("Metadata:", gefData.metadata);
  } else if (gefData.type === "bore") {
    // Borehole data with soil layers
    gefData.data.forEach((layer) => {
      console.log(
        `${layer.soilCode} from ${layer.depthTop}m to ${layer.depthBottom}m`,
      );
    });
    console.log("Specimens:", gefData.specimens);
  }
});

With Node.js reading GEF file from filesystem:

import { readFile } from "fs/promises";

const buffer = await readFile("path/to/file.gef");
const file = new File([buffer], "file.gef");
const gefData = await parseGefFile(file);

Coordinate Conversion

Convert GEF coordinates (typically Dutch RD or Belgian Lambert) to WGS84:

import { convertToWGS84 } from "@bedrock-engineer/gef-parser";

const result = convertToWGS84({
  x: 155000, // RD x-coordinate
  y: 463000, // RD y-coordinate
  epsg: 28992, // Dutch RD coordinate system
});

if (result.success) {
  console.log(`Lat: ${result.lat}, Lon: ${result.lon}`);
}

Depth Correction

Apply depth corrections for inclinometer data:

import { addComputedDepthColumns } from "@bedrock-engineer/gef-parser";

// Adds corrected depth columns based on inclinometer measurements
const correctedData = addComputedDepthColumns(gefData.data);

API

Main Functions

• parseGefFile(file: File): Promise<GefData> - Parse any GEF file
• parseGefCptData() - Parse CPT-specific data
• parseGefBoreData() - Parse borehole-specific data
• processCptMetadata() - Extract CPT metadata
• processBoreMetadata() - Extract borehole metadata

Types

All types are exported from the main entry point:

import type {
  GefData,
  GefCptData,
  GefBoreData,
  GefHeaders,
  ColumnInfo,
} from "@bedrock-engineer/gef-parser";

License

Apache-2.0

By Jules Blom at Bedrock.engineer