From Wikipedia:

Shared space is an urban design approach which seeks to minimise the segregation of pedestrians and vehicles. This is done by removing features such as kerbs, road surface markings, traffic signs, and traffic lights. It has been suggested that, by creating a greater sense of uncertainty and making it unclear who has priority, drivers will reduce their speed. This is conducive to a safer environment for both pedestrians and vehicles. Shared space schemes are often motivated by a desire to reduce the dominance of vehicles, vehicle speeds, and road casualty rates.

Shared space design can take many different forms depending on the level of demarcation and segregation between different transportation modes. Variations of shared space are often used in urban settings, especially those that have been made nearly car-free ("autoluwe"), and as part of living streets within residential areas. As a separate concept, "shared space" normally applies to semi-open spaces on busier roads, and here it is controversial.

Shared space is opposed in particular by organisations representing the interests of blind, partially sighted and deafpeople, who often express a preference for the clear separation of pedestrian and vehicular traffic.