Research Articletgis_1188 147..162
Spatial Planning on the Semantic Web
Rinke Hoekstra
Leibniz Center for Law
Universiteit van Amsterdam and
Computer Science Department
VU Universiteit Amsterdam
Radboud Winkels
Leibniz Center for Law
Universiteit van Amsterdam
Erik Hupkes
Leibniz Center for Law
Universiteit van Amsterdam
Abstract
Land use regulations are an important but often underrated legal domain. In densely
populated regions such as the Netherlands, spatial plans have a profound impact on
both (local) governments and citizens. This article describes our work on a ‘Legal
Atlas’. Using Semantic Web technology we combine distributed geospatial data,
textual data and controlled vocabularies to support users in answering questions such
as: “What activity is allowed here?” Spatial norms are represented using OWL 2 in a
way that enables intuitive visualisation of their effects: map-based legal case assess-
ment. Users can represent a (simple) case by selecting or drawing an area on the map.
Given a designation for that area, the system can assess whether this is allowed or not.
The same solution also enables the comparison of two or more sets of spatial norms
that govern the same region. We discuss the advantages and drawbacks of a number
of alternative solutions for representing and integrating metadata of spatial plans, and
the representation of normative conflicts and exceptions between norms.
1 Introduction
Land use regulations are an important but often underrated legal domain. Especially in
densely populated regions such as the Netherlands, spatial plans have a profound
impact on both (local) governments and citizens alike. They determine whether build-
ing permits are granted, businesses can expand, roads can be widened, housing
projects can be built, and even determine the chances of survival of endangered species.
Address for correspondence: Rinke Hoekstra, Leibniz Center for Law, Universiteit van Amsterdam,
Kloveniersburgwal 48, 1012 CX, Amsterdam, The Netherlands. E-mail: hoekstra@uva.nl
Transactions in GIS, 2010, 14(2): 147–161
© 2010 Blackwell Publishing Ltd
doi: 10.1111/j.1467-9671.2010.01188.x

Although spatial regulations can be characterised as normal regulations – given their
applicability within a spatially restricted jurisdiction (e.g. a country) – spatial plans
regulate at a much more fine-grained level, where individual norms may apply only to
specific locations or regions (often called zones). In practice this has led to a situation
where the annotated map of a spatial plan is the dominant source of law, rather than
the textual description of the plan.
Over the past decade, web technology significantly improved the accessibility of legal
sources. This development not only meant the construction of Internet portals for
accessing legal texts, but also involved a standardisation of the structural description of
legal sources in terms of both web standards – such as XML – and interchange standards
– such as CEN MetaLex (Boer et al. 2002, 2008).1 Given the prominence of maps in spatial
plans, in order to improve access to these regulations a combination of existing technology
for disclosing legal texts with that currently available in geographical information systems
seems inevitable. Such a combination allows the connecting of textual descriptions as in
traditional legal sources, to the more object-oriented representation of the world employed
by the maps of zoning plans. The Legal Atlas (Boer et al. 2007, Winkels et al. 2007) was
the first system that combined MetaLex encoded texts with the corresponding maps
expressed in GML2 by using Semantic Web technology, RDF in particular.3 In this article
we show that this proves a solid approach for extending the functionality of Legal Atlas
well beyond straightforward information integration; i.e. to support not just concept-
based information retrieval, but rather map-based normative reasoning.
We identified three scenarios that Legal Atlas can serve:
Assessment – A citizen or company or a civil servant consults the regulations to see
whether a particular plan at a specific location is allowed. In case there is the option to
compensate somewhere else in order for the original plan to be approved, the system
should indicate this on the map. In the spatial planning domain it is sometimes allowed
to compensate for violating a norm in one area in another area, e.g. compensating the
building of houses in a park by turning another area into a new park.
Planning – A citizen or company consults the regulations to see where a particular plan
is allowed.
Evaluation – Someone wants to or needs to check the consistency of two sets of spatial
norms. The State Council in the Netherlands for instance, may need to check whether a
zoning plan of a city council fits the overall zoning plan of the province. A second type
of evaluation by a legislative drafter for instance may be to see what the consequences of
a new set of norms might be in practice. Suppose the idea is to prohibit “Dutch coffee
shops”4 in the vicinity of schools (an actual case in Amsterdam at the moment). If we
have access to a database of all schools in a certain area with geographical locations, the
consequence of various implementations of these norms (e.g. not within a radius of 500
or 1,000 m, etc.) can be plotted on a map. We can for instance see if any areas remain
where coffee shops would be allowed at all (cf. the “Planning” scenario above). If we also
have a database of all existing coffee shops in the area, we can determine the conse-
quences for these establishments.
2 Requirements
It is clear that Legal Atlas has to deal with the intrinsic heterogeneity of the information
it discloses: spatial plans are not just documents, but they are closely tied to maps. These
148 R Hoekstra, R Winkels and E Hupkes
© 2010 Blackwell Publishing Ltd
Transactions in GIS, 2010, 14(2)