GI-Forum 2014: Assessing bicycle safety in road networks

Assessing bicycle
safety in multiple
networks with different
data models
Martin Loidl
Department of Geoinformatics, Z_GIS
University of Salzburg
martin.loidl@sbg.ac.at
GI-Forum 2014, Salzburg

Context
 Why bicycle safety?!
2
www.zeitpunkt.ch
“Road safety: Second good
year in a row puts Europe
firmly on track towards
target” (EC - IP/14/341; 31/03/2014)
Another worrying feature of the statistics is the
situation of vulnerable road users: The number
of pedestrians killed is decreasing to a lesser
extent than expected and the number of
cyclists killed has recently even been
increasing. This is partly due to the fact that
more and more people cycle; the challenge for
Member States is to encourage people to
use their bicycles rather than their cars more
often, but to make sure that the shift from
car to bicycle is a safe one.

How can we contribute to safety
improvements for bicyclists?
3

Assessment
 Status-quo analysis
 Weak-point analysis
 Corridors
 etc.
 Planning & Infrastructure
 Priority of measures
 Budget allocation
 etc.
 Information
 Routing
 etc.
4
www.stadt-salzburg.at
www.stadt-salzburg.at
www.radlkarte.eu
AssessmentofNetwork

Assessment Method I
 Fuzzy results
 From grades to verbal description
 Assessment standard hardly to establish
 Person, time, location
 Requires much effort
 E.g. re-assessment after every physical
modification of road space
6
 Expert knowledge as input for assessment procedure
 Sub-optimal for global assessment approach

Assessment Method II
 Conceptual fallacy
 Absolute (!) number of accidents no indication
for unsafe roads
 Function of N
 External effects
7
 Accident analysis for detection of risk factors or hot spot
analysis
http://gicycle.wordpress.com

Assessment Method III
 Not equally distributed over space
 Coverage in remote vs. central areas
 Data
 Representative only for specific sub-groups
 Semantic challenge
 Ontologies for feedback assessment
8
 For punctual validation/calibration
 For group-specific analysis, qualitative assessment
 Not yet applicable for global assessment = research topic!

Indicator-based
Assessment Model
10

Problem Statement
 Bicycle routing service with „safety“ as routing criteria
 Different data sets from different sources
 Different data models
 Geometry and attributes
 Different environments to adapt the model for
 Urban vs. rural
12
type = road
bicycle_infra = cycleway
type = road
type = cycleway

Study Area & Data
 Authoritative data for city of
Salzburg
 11,458 edges
 1,119.7 km net length
 OpenstreetMap extract for
adjacent municipalities (1A, 4G)
 9,601 edges
 941.3 km net length
 Data sets with different data
model and attribute structure
13

Data models
 Authoritative graph
 Center line
 Complex attributive formulation of bicycle infrastructure
 Complete and homogeneous
14
DB-Name Attribute Value Value description
SIC_STRAS4 Road category 400Municipal road
SIC_STRAS5 Max.speed, km/h 50
SIC_STRA9 Buslane 1Yes, FT
SIC_STR13 Oneway 1Yes, FT
SIC_RAD_RE Bicycle infrastructure (right side, FT) 10Yes, undefined
SIC_RAD_R1 Bicycle infrastructure (left side) 5Cycle-/footway mixed
SIC_RAD_RI Direction bicycle infrastructure (FT) 0No
SIC_RAD_R5 Direction bicycle infrastructure (TF) 4Both directions, independet from oneway
SIC_STR24 Motorized traffic load, V/24h (TF) 0
SIC_STR25 Motorized traffic load, V/24h (FT) 17698

Data models
 OSM graph
 Edge for every physically separated
lane
 Very simple tag (key = value)
structure
 Up-to-date
 Gaps, inconsistencies, errors,
heterogeneous attribute structure
15
Key Value
highway path
bicycle designated
foot designated
surface paved
Loidl et al. (2014), Aufbereitung von Open Street Map Daten
für GIS-Modellierungen und Analysen. AGIT

Workflow
16
Define transition points
between networks
Line matching and
integration of transition
edges
Identify indicators for
urban and rural
environment
Find corresponding
attributes in digital data
Run indicator-based
assessment model for
both environments
Z-transformation for
index values
Rivers » bridges
Highway » ring underpasses

Geometry & Topology
17
 Transfer points
 Bridges, under-/overpasses
 Transition edges
 Line matching

Conclusion
 Indicator-based assessment model
 Transparent
 Comparable
 Adaptable and scaleable
 Reproducable
 Applicable in several contexts
 Proof of concept: safe bicycle routing
 Planning and simulation tool
 GIS „intelligence“ helps for modelling in heterogeneous
environment (data, geography, …)
21
@gicycle_
gicycle.wordpress.com

GI-Forum 2014: Assessing bicycle safety in road networks

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GI-Forum 2014: Assessing bicycle safety in road networks