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This article introduces Inkscape and OpenSignTool. It also discusses how to install OpenSignTool and a sign design color palette.


Most traffic engineers or technicians design traffic signs with a commercial Computer Aided Design (CAD) software package and a plug-in sign program developed specifically for the CAD software. Often times, both the CAD software and sign program are designed by software developers without sign design knowledge. Those software tools are ofter very expensive and difficult to learn and use.

The open source community has created many excellent software applications in the past few decades. The software authors make the source code available to others who would like to learn, modify, and improve it. Anyone can freely copy, alter, and share the code.

Inkscape is a successful open source vector graphic design software application. It came into existence in 2003 with code from other open source projects. The current release version 1.1.2 is mature and stable, and a large open source community is actively improving it. The software tool is very capable, and people often compare it to Adobe Illustrator regarding its functionality.

Inkscape software itself is written in C/C++ programming language. It includes a Python programming language based extension system as a way to extend its functionality. Each copy of Inkscape software distribution includes hundreds of built-in open source Python extension programs.

OpenSignTool is an open source traffic sign design software package. It consists of several Python extension programs written for Inkscape. OpenSignTool closely follows the traffic sign design standards in the US. The tool has been utilized to create thousands of sign graphics. OpenSignTool source code is freely available on

Inkscape for Sign Design

The Inkscape software has a large user base in the graphic design community. Many design professionals and hobbyists use it to create a wide variety of graphics such as illustrations, icons, logos, diagrams, maps, and web graphics. Here are some advantages of Inkscape over other drawing software packages:

  • It is free and open source.
  • Basic drawing and editing tools are very good and reliable.
  • File format support is extensive. It supports most popular vector graphic file formats.
  • The native file format SVG is an open file format.
  • It is available on Windows, Linux, and Mac OSX platforms. The extension programs developed for Inskcape such as OpenSignTool can run in those platforms without modification.

Inkscape has many fundamental drawing and editing tools that a traffic engineer can find in other computer graphic software packages. The essential drawing tools for traffic sign design are selector, node, rectangle, ellipse/arc, bezier, text, and guideline. The editing tools fill and stroke, font and text, transform, align and layer, snapping and guide are also indispensable during sign design.

Inkscape supports most popular vector graphic file formats. Drawings are imported and exported in Drawing eXchange Format (DXF) file format to interact with CAD programs. Encapsulated PostScript (EPS) file format is the preferred choice with Adobe design software. Enhanced Meta File (EMF) file format is often associated with Microsoft Office applications. It also supports most raster image file formats. The default Inkscape file format is Scalable Vector Graphics (SVG). The SVG specification is an open standard developed by the World Wide Web (W3C) consortium. SVG files are XML based text documents. All major modern web browsers support SVG rendering and can open SVG file and view the drawings.

Here are some good learning resources if you are not familiar with the software

OpenSignTool Installation

To install an Inkscape extension, download and unzip the extension file. Copy the files into extension directory. After a restart of Inkscape, the new extension will be available under the menu Extensions. We will describe the steps in more details in the following sections.

Download and Unzip

On your Internet browser window, click the Download button on the home page of this website or click here to download a zip file. On the left bottom corner of the browser window, you will see the link to the download file. Click the upward pointing arrow, and click “Show in folder”.

download file

In the file browser window, find the downloaded zip file “”. Right click the file, and choose the menu item “Extract Here”. It will create a “OpenSignTool1.1.31522” folder. Open the folder and you will find 15 OpenSignTool extension program files.

unzipped files

Select all 15 files and right click the selection, and click “Copy” on the menu to copy those files to the clipboard.

Copy Files to Extension Folder

The next step is to start Inkscape and find the extension folder. If you don’t have Inkcape install, you can find installation and setup information on this webpage. On the Inkscape window, click the Menu Edit -> Preferences.

On the left hand side of the Preferences window, click the “System” menu item. Then you will find many system settings on the right hand side.

preferences window

Click the Open button on the right hand side of “User extension” folder. The “User extensions” setting has the following value under Ubuntu Linux system. The setting will be difference under Windows system.


On the opened folder window, right click and select the menu “Paste”. This step should paste all 15 files into this extension directory.

Verify Installation

You can now close the Inkscape and restart the program. Click the Extensions menu and you should find a submenu OpenSignTool.

preferences window

Inkscape Sign Color Palette

Traffic signs (or any traffic control devices) are restricted to use eleven colors specified in the 2009 Manual on Uniform Traffic Control Devices (MUTCD). Two colors, coral and light blue, are reserved for future use. Three colors orange, red, and yellow have fluorescent versions, but the fluorescent colors do not count as separate colors. The fluorescent pink and fluorescent yellow-green count as separate colors because they don’t have non-fluorescent versions. The other six colors are black, blue, brown, green, purple, and white.

The table below shows red, green, and blue (RGB) color values extracted from 2009 MUTCD and 2012 Supplement to Standard Highway Signs. The contents of are saved in a file Traffic-control-device.gpl in the Inkscape palette directory, and a color palette named Traffic Control Devices will show up in Inkscape. Users may choose any one of those colors. The RGB values are the same as the values of sign graphics found in the 2009 MUTCD and 2012 Supplement to Standard Highway Signs.

GIMP Palette
Name: Traffic Control Devices
# generated by
 35  31  32  Sign Black
  0  86 150  Blue
121  69  00  Brown
241  94 124  Fluorescent Pink
193 215  46  Fluorescent Yellow-Green
  0 111  81  Green
244 145  30  Orange
108  39  124 Purple
191  46  26  Red
255 255 255  White
255 210  79  Yellow
255 127  80  Coral (Reserved)
 90 147 193  Light Blue (Reserved)
  0   0   0  Black Ink
255   0   0  Red Ink
  0   0 255  Blue Ink

Here are the steps to setup the sign design color palette in Inkscape.

  1. Download the “Traffic-control-device.gpl” file by clicking the link below.
    Traffic-control-device.gpl file

  2. Copy and paste the file into the palettes folder. The folder address can be found on the Preferences dialog (Menu Edit -> Preferences). It is under the name “User palette”. Click the button “Open” next to it.

preferences window

3. Close and restart Inkscape. Click the right bottom arrow to bring up the palette setting menu. Select the new Traffic Control Devices palette. You can now use the colors on the bottom palette bar.

palette window

What’s Next?

The general procedure of designing a traffic sign with Inkscape and OpenSignTool is to first create the sign border with the Draw Border tool, then to add sign messages with the Place Message Line tool. If a user is designing a non-standard sign or a sign that has a varying width message, the process will be iterative. The user would begin with the sign border, add the sign message, go back to modify the border, and then modify the message until a satisfactory layout is achieved. Auxiliary lines are added for alignment purposes with the Place Alignment Lines tool. The signs are drawn in true scale in inches. A user increases or decreases the drawing size with the Inkscape transform scale tool.