# BIM-Based Description of Intelligent Transportation Systems for Roads
###### Abstract
The IFC Road project, conducted by bSI, aimed to create a candidate standard, which extends the IFC schema for roads, e.g., developing data models for geometry, road body shape, earthwork, and semantic information for roads, and integrating use cases relevant to the road life cycle. With all deliverables of the IFC Road being published, the project was finalized in 2020 [23]. Moreover, several studies have been conducted to integrate further infrastructure elements into the IFC schema. For example, [PERSON] and [PERSON] (2011) have proposed an IFC extension for road structure, defining infrastructure segments in terms of IFC entities, such as _IfcPavementLayer_, _IfcBridgePier_, _IfcTumnelLining_, and _IfcInspectionLadder_[24]. The authors have used an example of a road section with combined bridge and tunnel segments to validate the proposed IFC extension, illustrating entities that define longitudinal and curvilinear sections of road infrastructure. [PERSON] et al. (2015) have shown the extendibility of IFC Alignment when introducing the _IfcCrossSections_ entity, which defines static and dynamic cross sections for junction-free roads [25]. A comparative study between the IFC schema and spatial elements required for tunnel design is presented in [26]. The authors later introduced an extension that defines entities for main components in tunnel structures, such as _IfcShotcrete_, _IfcSteelRib_, _IfcRockBolt_, and _IfcConcreteLining_, and have validated the extension using a real tunnel construction, which has been compared with an IFC-based BIM model. [PERSON] et al. (2018) have defined additional elements for semantic information management of steel box girder bridges using Industry Foundation Classes, Version 4 (IFC4), with user-defined property sets for spatial arrangement of the structure and physical structural components during planning and design phases [27]. Despite the extensive capabilities to describe infrastructure information for physical road components, the IFC schema provides just a few entities that may be used for describing the \"cyber\" components of ITS for roads. For example, _IfcSensor_ provides a sensor description for predefined objects, such as temperature sensors, and may partially be employed to define sensing units of ITS intelligent infrastructure. The IFC entity _IfcCommunicationsAppliance_ may specify communication units of ITS intelligent infrastructure usingpredefined property sets [28]. Although not specifically designed for describing ITS, studies have been conducted aiming to fill the gap in data models for cyber-physical components, such as actuators and sensor networks. [PERSON] et al. (2017) have presented an IFC extension that defines entities related to cyber-physical systems deployed for monitoring and control applications [29]. The authors have defined _IfcSensorNode_, _IfcSensorNetwork_, and _IfcMonitorSControlSystem_ as CPS-related new IFC entities to describe sensor nodes, sensor networks, and structural health monitoring (SHM) and control systems, respectively. Later, [PERSON] and [PERSON] (2018) defined IFC Monitor, an IFC extension for describing monitoring-related information, adding enumeration entities _IfcNetworkTopologyEnum_ and _IfcSensorTypeEnum_ for predefined network topologies and additional sensor types, respectively [30]. From the information stated above, it is concluded that the existing capabilities of the IFC schema for describing intelligent transportation systems are limited to a few IFC entities for describing infrastructure information for physical road components. To this end, an extension to the IFC schema is required to fill the gap with respect to entities devised for describing the \"cyber\" components of ITS for roads, i.e., entities not yet available in the IFC schema but relevant to BIM-based modeling of ITS for roads. In this paper, for creating a formal description of ITS for roads facilitating BIM-based simulations, a semantic model for ITS for roads is proposed.