Technische Universität München
IFC Infrastructure
Alignment representation
TUM Proposal
André Borrmann, Julian Amann, Technical University Munich
Chair of Computational Modeling and Simulation
Motivation
 all linear infrastructure facilities
are based on alignment definitions
 this applies to
 roadway, railways
 bridges
 tunnels
 etc.
 a comprehensive definition of
an alignment model is required as a
sound foundation for IFC-Infrastructure
Technische Universität München
Chair of Computational Modeling and Simulation
Technische Universität München
Alignment as basis for future IFC-Infrastructure
IFC-Alignment
IFC-Tunnel
….
IFC-Tunnel
IFC-Bridge
IFC-Road
IFC-Infrastructure
Chair of Computational Modeling and Simulation
Technische Universität München
Carriageway Design
Conventional 2D approach
implicit 3D geometry
 Horizontal alignment
 Vertical alignment
 Cross-section profile
 established methods
 reduction of design complexity
 mature 2D design / drawing systems (ProVi, Civil3D, …) & Standards (LandXML, OKSTRA, …)
Chair of Computational Modeling and Simulation
Technische Universität München
Technical Background
2D Road Alignment
3D Road Alignment
2D Vertical Alignment
2D Horizontal Alignment
2D Road Profile Definition
Horizontal Alignment
3D road alignment geometry implicitly represented
by 2D alignment designs
Chair of Computational Modeling and Simulation
Technische Universität München
Horizontal Alignment
Horizontal Alignment Elements
 Line
 Transition Curve
 Clothoid
 Cubic curves
y
 etc.
 Circle Segment
Sn : length of curve
x
X-Y-Plane
Chair of Computational Modeling and Simulation
Technische Universität München
Vertical Alignment
Vertical Alignment Elements
 Line
 Circle Segment / Parabola
z
s
S-Z-Plane
Technische Universität München • Chair of Computational Modeling and Simulation
Current IFC-Bridge Draft
André Borrmann – [email protected]
Technische Universität München • Chair of Computational Modeling and Simulation
Current IFC-Bridge Draft
Shortcomings
Horizontal A.
 any IfcCurve can be used to define the alignment
 station information is not present
 there is no relationship between
the horizontal and the vertical alignment
PVI
 parabola does not exist
 roadway design information is not captured
Vertical A.
 Points of Intersection
 Points of Vertical Intersection
 the alignment cannot be precisely captured
André Borrmann – [email protected]
PVI
Technische Universität München • Chair of Computational Modeling and Simulation
Current IFC-Bridge Draft
Problem:
HorizontalAligment and VerticalAligment can be any IfcCurve
 lack of rigor
 alignment-specific information cannot be stored (e.g. station)
André Borrmann – [email protected]
Technische Universität München • Chair of Computational Modeling and Simulation
Data model proposal: Horizontal alignment
We introduce the entity
IfcHorizontalAlignmentSegment
to explicitly define what is
allowed for describing the
horizontal alignment.
We use an ordered list
to store the segments.
IfcTransitionCurve
can be subclassed to provide
extension mechanisms.
The Clothoid is encapsulated
by this entity.
The circular segment
is encapsulated by this
entity.
André Borrmann – [email protected]
The standard IFC entity
IfcTrimmedCurve, which
represents the actual geometry.
Technische Universität München • Chair of Computational Modeling and Simulation
Data model proposal: Vertical alignment
We use an ordered list
to store the segments.
We introduce the entity
IfcVerticalAlignmentSegment
to explicitly define what
geometry is allowed for
describing the vertical alignment.
Abstract
superclass to
provide
extendibility
The PVI associated with the parabola
André Borrmann – [email protected]
The Intersection Point Distance.
Technische Universität München • Chair of Computational Modeling and Simulation
Modifying a horizontal alignment
André Borrmann – [email protected]
Technische Universität München • Chair of Computational Modeling and Simulation
LandXML
•
Horizontal Alignment is described by Lines, Spirals and Curves
André Borrmann – [email protected]
Technische Universität München • Chair of Computational Modeling and Simulation
LandXML
•
Vertical Alignment is described by PVIs (Point of Vertical Intersection) and
ParaCurves
André Borrmann – [email protected]
Technische Universität München • Chair of Computational Modeling and Simulation
Discussion

we need a sound alignment representation as basis
for all linear infrastructure facilities (roads, tunnels, bridges, etc.)

current IFC-Bridge draft has some shortcomings (lack of rigor, missing information)

we propose the introduction of the entities
IfcVerticalAligmentSegment and IfcVerticalAlignmentSegment
for restricting the possible elements and storing additional information

original design information (PI, PVI, etc.)
 allows for later modification
 not a must, can be optional
 can be included/excluded in different model views

TUM will develop a translator LandXML  IfcAlignment
to facilitate transition and help to establish the new standard
André Borrmann – [email protected]
Technische Universität München • Chair of Computational Modeling and Simulation
Discussion

now there is number of alignment proposals on the table
 we need to achieve convergence
 another Alignment workshop is necessary (strongly technically)
© Stuart Chen
André Borrmann – [email protected]
Technische Universität München • Chair of Computational Modeling and Simulation
IfcProject
Open Question
IfcRelAggregates
Usage of Alignment: Current Approach
IfcBridge
Project Hierarchy
IfcRelAggregates
IfcBridgePart
IfcRelContainedInSpatialStructure
IfcBridgePrismaticElement
Standard Way of Defining Geometry Representation
IfcProductDefinitionShape
can also be a IfcReferenceCurveAlignment2D
IfcShapeRepresentation
Reference System (specific to IFC-Bridge)
Profiles
IfcReferencedSectionSpine
3
IfcReferenceCurve3D
IfcReferenceCurvePlacement
3
IfcArbitraryProfileDefWithVoids
*
IfcReferenceCurvePlacementSystem
IfcPolyLine
Why Polyline?
no of profiles
= number of
reference curve
placements
IfcPolyLine
IfcDirection
Orientation of the profile
What is the role of the placement system?
André Borrmann – [email protected]
Why can we not just assign
a position to each profile?
Technische Universität München • Chair of Computational Modeling and Simulation
Case study
Second Main Subway Track in Munich
André Borrmann – [email protected]