# I-BIM Applied in Railway Geometric Inspection Activity: Diagnostic and Alert
## 2 Materials and Methods  
The study followed a work methodology composed of three main sequential steps aiming to reach relevant and useful conclusions for the I-BIM community regarding the railway infrastructure sector, with a focus on the inspection activity (Figure 1). * BIM modeling process: The first stage refers to the BIM modeling process in order to conceive of an accurate representation of the infrastructure it analyzed. A BIM model is a comprehensive 3D digital representation of the infrastructure, imposing a high demand on geometric and semantic data. The railway track components were mainly related to rails, fastenings, sleepers and layers of ballast. The available BIM modeling software did not contain libraries of parametric objects related to the railway infrastructure. As such, the geometry, the material and the related position of the components were carefully analyzed, based on the literature. This bibliographic access supported the generation of the required new parametric objects, accurate geometry and physical proprieties of the associated materials. Although the advanced modeling systems lead to advantages well highlighted by practice, in the case of transportation infrastructure, a time-consuming effort was required in this step. A new  
Figure 1: Scheme of the methodology applied in the research. set of parametric objects were then generated, allowing the creation of BIM models of railway infrastructure. * Railway inspection activity: Next, the railway inspection activity was deeply studied, referring to the identification of the most frequent geometric irregularities and to the traditional inspection practices, considering mechanical, manual and semi-automatic processes. The railway track elements are susceptible to degradation caused by vehicle circulation characteristics (frequency of use, vehicle speed and volume of transported cargo), environmental aspects, infrastructure stability and the fact that the track is supported on a ballast layer subject to displacements in horizontal and vertical directions [24]. Infrequent or inadequate rail inspection plans can provoke negative consequences, and as such, a careful planning schedule of periodic inspections must be well defined and applied. During the inspection process, information about track conditions is collected, recorded and analyzed, and then recommendations can be made, and maintenance actions can be completed. Some of the parameters generally measured in a railway inspection include position, curvature, alignment of the track, smoothness and the cross level of the two rails. Through the utilization of track evaluation equipment, it is possible to determine the values of these parameters and compare them to the safety standards. In this way, it is possible to verify the presence and identification of anomalies, determine their causes and perform the needed repairs. As a case study, an illustrative segment of a real railway track was considered, supporting not just the modelling process, but also the collection of data inspection and the evaluation of the Dynamo script efficiency. * Dynamo script development: With the aim of introducing BIM as an innovative contribution to railway infrastructure, and in order to contribute to improving the general digital transformation of the construction industry, a new approach was considered based on Dynamo programming. A Dynamo script was developed allowing users to insert the collected inspection data into the 3D BIM model, and to handle the database supporting the geometric incurrences evaluation and the emission of alerts regarding the level of severity of the detected anomalies. The script allowed for the analysis of the geometric railway inspections' data, its application over the real case study and the emission of an alert visualized over the model components.