User:RobJN/Extended Restrictions
Extended Restrictions are used to indicate additional information about a restriction. Existing tag keys such as access, oneway, maxweight and maxspeed are extended by appending the extra details to the end of existing tag key. The additional information may include:
- The type of transportation mode (vehicle category) affected
- and/or the direction in which the restriction applies.
If further information is required in order to accurately capture the full nature of a restriction, these can be expressed as 'true conditions' and tagged using the 'Conditional Restrictions' tagging scheme.
Overview
Restrictions are used to limit use of a highway in some way. This may be to prevent use by a sub-group (for example, vehicles over 12 meters in length), or to impose conditions on it's use (for example a maximum speed of 80 km/h). To understand how to tag restrictions it may be helpful to classify the restriction by its level of complexity:
- Simple Restrictions: Long standing tags such access, oneway, maxweight and maxspeed, and so on, are used to easily add basic restrictions to OpenStreetMap. Although they are the easiest to understand the tags are limited to just the most basic of cases.
- Extended Restrictions: If the restriction only applies to certain transportation modes (vehicle category) or directions, the tag key can be extended by appending this information after the restriction type. This is the topic of this page.
- Conditional Restrictions: In some cases restrictions are only valid when certain conditions are fulfilled. Examples may be cars not allowed on Sundays or a lower maxspeed applicable between 6:00 and 20:00 - see more.
The tagging scheme described here explains how to add 'Extended Restrictions' to OpenStreetMap.
Tagging
The general syntax (where fields in square brackets [..] are optional) for Extended Restrictions is:
<restriction-type>[:<transportation mode>][:<direction>] = *
Key
The key is constructed by adding the transportation mode (vehicle type) and/or the direction to the basic restriction tags.
Restriction type
This can be any type of restriction that may have conditional validity. Common examples are access, maxspeed and oneway restrictions. The restriction type should reflect the main traffic sign. For this 
sign having an additional sign specifying a condition the type should be access. On the other hand for this sign 
the restriction type should be maxlength (similar for other max<dimension> signs).
Transportation mode
This key-part specifies the vehicle category or transportation mode to which the restriction applies. E.g. bicycle, motor_vehicle, foot, agricultural. For access restrictions it is allowed to use the abbreviated form by omitting access: in front of the category. E.g. motorcar instead of access:motorcar. Please note that the value agricultural designates the type of vehicle (not the purpose of the highway use) and is therefore a valid transportation mode. For "By use" modes (hov, emergency, hazmat, disabled) it is however recommended that you consider these to be true conditions and therefore tag the restriction using the 'Conditional Restrictions' tagging scheme.
- See Key:access for the full transportation mode hierarchy.
Direction
Some restrictions are direction dependent. Use forward and backward to indicate in which direction the restriction applies.
Value
The tag value should follow the guidance provided for the restrictions types basic restriction tag.
Examples
Examples of these extended restrictions include: