Introduction

Barriers and access tags are important in OSM as they provide valuable information on accessibility and routability. This guide will provide definitions and propose a workflow for mapping these features in OSM.

Key Terms and Definitions

Here are some basic terms and definitions that help clarify how to tag barriers and access tags.

Implicit Classifications:	Highway classifications that imply a certain mode of transport is permitted or prohibited by default without further tags necessary to enforce the access restriction. Sometime self-evident in the name. There are two universal implicit classifications in OSM: `highway=motorway` implies `foot=no` `highway=footway` implies `foot=yes`
Innavigable Way:	Way cannot be accessed by any means. Way cannot form part of a route.
Terminal Way:	A road that does not allow thru traffic. Contains the beginning or endpoint of a route.
Enclosed Area:	An area with a closed perimeter of walls and fences. There are barriers controlling access at every point of entry. At least one barrier is a gate.
Gated Community:	An enclosed area of residential housing.

Prerequisites

Familiar with JOSM, highway classifications, and road geometry.
Review access implications of highway classification tags. Specific highway classifications make some access tags redundant. We want to avoid adding redundant tagging.
Familiar with ground imagery platforms (Mapillary, Kartaview, etc.)

Skill Instruction

Barriers

A barrier is a physical structure that blocks or prevents movement. To map barriers in OSM, an editor will add a barrier=* tag to a node or way depending on the type of barrier.

How to Map

Before we add a new barrier we first need to determine if it will go on a node or a way. To do this we'll reference both ground and aerial imagery to identify what kind of barrier it is and how it should be tagged.

Nodes

Barrier nodes are placed where the barrier structure is visible in aerial or ground imagery (where available).

Use available imagery to identify where the barrier(s) is/are.
Split the ways where the barrier(s) is visible.
Add the appropriate barrier=* tag based on ground imagery.
- Some barriers can be added to areas as well.

Note: Never connect a barrier to a highway junction as this will block routing for ALL incoming ways.

Some barriers have implied access tags, meaning you are required to stop to request permission before proceeding through the barrier.

The following types of barriers have implied access(access=permissive):

Linear Barriers(Ways)

Linear barriers include fences and freestanding walls. These are added as line features and are often used to enclose areas.

To add a linear barrier:

Use available imagery to identify where the barrier is.
Draw a line where the barrier can be seen in aerial/ground imagery.
Add the appropriate barrier=* tag.

Common Barriers

Below is a list of common barrier tags that Kaart uses. These are identified in the Kaart paint style with a green casing. For more information on this see the Kaart Paint Style page.

`barrier=gate`	Any section of wall or fence which can be opened to allow or block access.
`barrier=lift_gate`	Vehicular access is blocked using one or two horizontal bars. The bars are raised and lowered either electronically or manually.
`barrier=bollard`	A post installed to block entrance by most vehicles or prevent motorcars from colliding or crashing into pedestrians and structures.
`barrier=block`	A large, solid, immobile object—typically made of concrete or similar material—that can only be moved with heavy machinery or significant effort.
`barrier=jersey_barrier`	A jersey barrier consists of heavy prefabricated blocks which create a barrier blocking access or separating lanes. They have a distinctive shape. Often made of concrete, but can be plastic, filled with sand or water.
`barrier=kerb`	A kerb is a low profile barrier that is located at the edge of a road that separates it from a sidewalk or a path.