# A BIM-Enabled Workflow for the Rehabilitation of Heritage Steel Bridges
## 3 The Information Management Framework
### The Information Delivery Specification  
Following the development of the OIRs, AIRs, and PIRs, the creation of a technical document, called an information delivery specification (IDS), is usually recommended, as it ensures the seamless integration of information requirements into practical workflows. The IDS serves as a technical document that translates natural language and unstructured information requirements into actionable specifications for information exchanges. It bridges the gap between strategic requirements and technical implementation, ensuringthat the data delivered align precisely with the expectations set out in the OIRs, AIRs, and PIRs. Technically, the IDS [58] is a standard development by buildingSMART to define information requirements in a way that is easily read by humans and can be directly interpreted by computers. It defines the structure, format, and level of detail required for each information exchange, promoting consistency and interoperability across teams and software platforms. It outlines clear rules for data quality, validation, and delivery milestones, facilitating smooth transitions between project phases and ensuring compliance with standards like ISO 19650 [24]. For instance, during the design phase of a steel bridge, metrics such as bill of material accuracy, 3D model completeness, correlation with in-field measurements, and assembly information consistency are pivotal in validating whether the information meets predefined standards and project requirements. Accuracy ensures that quantity, dimensions, tolerances, and material properties are correctly represented in the design models. For example, the specification of steel grades must align precisely with the requirements for load-bearing capacity, environmental conditions, and heritage structure rehabilitation. Completeness ensures that all necessary details, such as connection types (e.g., riveted, bolted or welded joints, if allowed) and cross-sectional geometries, are included in the model to avoid ambiguities during fabrication. Consistency verifies that different aspects of the design--such as the alignment of trusses, bracing systems, and load distribution calculations--are coherent across various models and drawings. Validation during this phase directly influences decisions regarding the next project phases. Accurate material specifications can support the most cost-effective procurement strategies while ensuring that the selected materials meet both heritage rehabilitation, performance, and sustainability criteria. Similarly, validated geometric data support the performance of structural simulations to predict the bridge's response to future loads, such as vehicular traffic or environmental stresses, informing decisions on reinforcement strategies and correct material use, and thus potentially reducing costs without compromising safety  
As the project transitions to the construction phase, these validation metrics ensure that the information used for execution aligns closely with the design intent, minimizing discrepancies that could lead to rework and project timeline extension. Accurate and complete design information, validated during the design phase, ensures that misalignments are avoided during the construction phase, which is particularly crucial for complex structures like skewed or curved steel bridges. Inconsistent or incomplete data at this stage, more often than not, result in costly fabrication errors and delays during erection. It must be mentioned that IDS is particularly critical for managing BIM workflows, as it provides clarity on how the information should be produced, shared, and utilized. Moreover, IDS mitigates risks associated with incomplete or inaccurate data, which can lead to inefficiencies, cost overruns, and delays. An important scope of IDS is that it only focuses on 'information delivery specifications', meaning that it can define what information is needed and how it should be structured.