Entrant details
Role or Job Title on the Project
BIM coordinator and PhD candidate
Employer
Employer Role
Architecture or Engineering Company
Are you or your employer a member of buildingSMART?
Yes - Sponsor Member (Standard, Multinational or Strategic)
Submission details
Submitting Party Company Name
COWI
Submitting Party Company Location
Bergen, Norway
Submitting Party Role on Project
Design consultant
Submitting Party Company Website
Full Project Name
Fv. 547 - Åkra sør - Veakrossen
Project Location (Country)
Norway
Project Objectives
The project's main objective was to build a 7 km single-lane highway that bypasses the local community center including four crossings to connect with local roads. The secondary objective was to enable and enforce digital workflows between the stakeholders in the project. Traditional drawing-based workflows were to be replaced by model-based workflows. Therefore, the client demanded only a limited number of drawings for the benefit of digital models for all disciplines in an open format.
openBIM Achievements
We could not only digitalize but also automate workflows by creating a link - a specifically coded PSet - from four design programs to a cost estimation software. By using a custom-made PSet instead of mapping the IFC entities, we could not only adapt the workflow to road entities but also collect all cost relevant properties within one information module. This helped estimators with low BIM knowledge to find the information needed for cost estimation faster. The time consuming and error prone process with cost estimation was reduced by 50%. Automation of the cost estimation reduced manual errors to 0.
openBIM used
IFC 2x3
Software used
Novapoint, Revit, Tekla structures, Civil 3D, Rhino with Grasshopper, Dynamo, SimpleBIM, ISY Beskrivelse
Strategic Alignment
Traditional manual workflows for creating the specification of work and the cost estimation were digitalized and automated based on existing pre-BIM standards. In addition to simply digitalizing traditional workflows, we added value downstream in the supply chain, reduced redundancy of information and improved the productivity within the project by automation.
Highlights
- Co-operation between a consulting company and a research institution
- Paper-less project in practice using model-based design to enable digital workfows
- Client demanded only a limited number of drawings
- Specification of work and cost estimation were automated
- 4 design programs linked to a cost estimation software by specifically coded property set based on IFC (2x3)
- Cost relevant information was collected in one information module in the form of a property set
- 70% of all cost items were mapped to model entities
- 50% time reduction, especially at revisions
- Manual errors reduced to 0
- Workaround for not yet defined road entities in IFC (2x3)
- Estimators with low BIM knowledge could find the necessary information faster
Project Website
Project Address
Project Type
Civil
Size of Project
- 7 km single-lane highway
- 3 km local roads
- 4 crossings (thereof two level-free)
- 7 bridges
- 12 underpasses
- Project cost (2020 estimate): 700 MNOK (64 M €)
Detailed description of the project
Åkrehamn is a local community center with approximately 8000 inhabitants on the island of Karmøy in Western Norway. Since the late 1970s, different alternatives for a bypass road have been assessed. The traffic into the regional center, Haugesund, continued to grow, and in 2016 a new project was initiated to realize the bypass road. The project was in 2020 estimated to cost 700 MNOK, approximately 64 M €. It consisted of the bypass road (a 7 km single-lane highway), 3 km local roads, four crossings (thereof two level-free), 7 bridges and 12 underpasses.
The road owner is the Rogaland county council. However, until January 2020 all road design work for county roads was administered and executed by the Norwegian Public Roads Administration (NPRA) . It was therefore NPRA's personnel and standards that made up the contractual basis for the project. The project delivery method was design-bid-build and both concept development and detailed designing phases were covered. NPRA signed a contract with the multinational design consultant COWI to produce both a zoning plan and a detailed design, including a specification of work.
It was one of the first road projects by the NPRA to enable and enforce digital workflows between the stakeholders. Core elements in these workflows were open standard models and a drastic reduction of the number of drawings. In the tender documents only drawings necessary for the licensing process were demanded. These drawings were a zoning plan and overview drawings for the designed constructions. The project was ordered "model-based" with discipline models delivered in open source formats like defined in NPRA's design manual V770. The core element of this manual is a mandatory BIM approach for infrastructure projects. In fact, the ambition was to deliver the project with no further drawings than those demanded by the client and the design consultant fulfilled this ambition. In total, 50 models in IFC (2x3) for all disciplines (road, construction, water & sewer, electrical, landscape and earthworks) were created by the design consultant. In total, these discipline models consisted of 175.076 model entities. Only a zoning plan and some overview drawings for the constructions were produced. This project was at the crossing between BIM level 2 and 3, as defined by the UK government's 2011 Construction Strategy.
The project team realized that this level of digitalization meant a rethinking of traditional workflows. However, it was the ambition of the project team to not only digitalize traditional workflows but also to add value through automation. In cooperation with the Norwegian University of Science and Technology (NTNU), one workflow, namely cost estimation, was chosen for further investigation. Cost estimation has traditionally been a manual and repetitive task prone to human error, something which has reduced its reliability for the contractor. However, contractors need exact and reliable information about the planned assets in a project, especially for cost drivers like constructions and masses for road layers. Therefore, an automation of cost estimation seemed like a promising solution. The digitalized workflow was based on existing pre-BIM standard specification of work texts. These specifications were published in two handbooks, R761 and R762. Only commercially available software was used.
Detailed description of openBIM on the project
With drawings missing, the design consultant had to rethink the established workflows. In 2016, the support of IFC was limited in the most used design and estimation software for infrastructure projects in Norway. However, in 2019 improvement made it possible to automate a workflow from four different design programs to a cost estimation software. This workflow was based on the IFC (2x3) schema.
The BIM team had workshops with the discipline leaders where they jointly screened Norwegian standard specification texts used for road projects. The goal was to identify cost items suitable for automatic quantity take offs. Finally, 480 cost items were identified. Then, the corresponding entities were identified in the discipline models and coded properties were added to a specific property set according to the NPRA’s general specifications. The relevant entities were expanded with a set of specifically named properties containing the specification data from the handbooks R761 and R762. These properties became a custom user-defined property set (Pset_ISY Beskrivelse) when exported as IFC (2x3) files. This specific property set lay the foundation for an efficient and precise exchange of information between four different design programs and a cost estimation software.
In detail, the property set consisted of the following properties: a unit (ISY Unit/ISY Enhet), a quantity (ISY Quantity/ISY Mengde), a numeric code (ISY Code/ISY Prosesskode), a title (ISY Title/ISY Prosessnavn), and an internal localizer (ISY Localizer/ISY Sted). They were used to map BIM entities to cost items in the specification of works. Depending on the geometry of each BIM entity, it was either identical to a cost item or had to be decomposed or attached to others.
While the property set was adapted to a workflow with one specific cost estimation software, the principle could be adapted to every cost estimation software which can extract cost relevant information from a property set in an IFC (2x3) file. Since we based our workflow on the open IFC standard we could integrate every design or estimation software that supports IFC, hopefully, soon also IFC4.3.
The four design programs allowed different levels of automation for assigning the necessary R761/R762 property set. In Novapoint, the decomposition of the entities to the respective cost items was done automatically by applying filters to the entire discipline model. In Revit, this was automated as well through the visual programming interface Dynamo and in Tekla through the visual programming interface Grasshopper. In Civil 3D, it was done manually by filtering the layers. The authoring software, Simple BIM, was necessary to edit some properties to a format that the cost estimation software could interpret. While this program could automate all of its actions by generic scripts, it was only half automatic in our case. Many functions use filters based on the IFC entity. Since road specific IFC entities are yet to become official buildingSMART standards, extra manually defined filters were needed.
As a next step IFC files were imported into a cost estimation software where cost items based on general specification texts were automatically created. ISY Beskrivelse ("Specification") from Norconsult Informasjonssystemer (“Information Systems”) was used as a cost estimation software. We verified several IFC sample imports against manually created bill of quantities. No disagreements between the IFC files and the manually created bill of quantities were found.
Benefits from using openBIM
IFC has recently emerged as the standard open format in infrastructure projects. With all software used in the project supporting IFC, we could not only digitalize but also automate workflows. One use case with major advantages was the creation of the specification of work and cost estimation. Since we based our digital workflows on the global open buildingSMART standards, we were able to create a robust and efficient platform fit for future developments.
ISY Beskrivelse (ISY Specifications), might resemble other cost estimation software e.g. VICO Office. One main difference is that ISY Beskrivelse solely extracts the quantities as numeric values from a predefined specifically named property set based on the IFC (2x3) schema and not from the IFC entities themselves. This has several advantages. Firstly, it makes it possible to automate the workflow also for IFC entities that are not yet defined in the IFC (2x3) schema, especially for road entities which mainly are exported as IfcSlab. Secondly, it makes it possible to attach several cost items to the same IFC entity without modelling it in the design software. For instance, a wall of natural stone has two cost items attached since it has a concrete sole and the backfill is protected by a geotextile. Instead of modeling these two cost items separately, their values are appended to the values of the wall. By separating the values with a semicolon ";" ISY Beskrivelse creates 3 independent cost items from this single IFC entity. There is just one property set in the IFC file (Pset_ISY Beskrivelse) which holds all relevant properties. The properties have several values which are interpreted independently by ISY Beskrivelse.
By building our workflows around the open buildingSMART standards, we could provide the estimator with an efficient tool. The relevant information for the estimator is presented in one information module in the form of a property set within an open standard model. This makes it not only easy to find all cost relevant information but also easy to integrate with different software. This helped estimators with low BIM knowledge to find the information needed for cost estimation faster. Moreover, the information is only stored in one place in an open format, pushed from the design software and pulled from the cost estimation software.
"We were able to innovate using openBIM."
We were able to automatically create a combined bill of quantities and specification of work based on 50 discipline models in IFC (2x3). The only missing element for a complete cost estimation were unit prices. These unit prices were added by the different contractors during tendering and were not part of the project scope. 70% of all cost items were either directly or indirectly mapped to corresponding model entities. All information necessary to create bills of quantities and a complete specification of work resides within the model, in one aggregated information module (property set). The cost estimation software extracts the necessary information from the IFC file. This solves redundancy of information – the same information is stored only in one location.
The presented automated workflow shifts the random human error made by manually copy-pasting numbers to systematic error made by machines. Automated workflows are not flawless, either, but instead of random errors they imply systematic errors which are easier to uncover.
Another observation was that BIM-based cost estimation could turn the traditional workflow upside down. Traditionally, estimators set up the different cost items first and supply them with quantities when the models have reached the necessary maturity. With an automated workflow, designers could map cost items to BIM entities directly in the design software and export IFC files. Estimators imported the IFC files into the cost estimation software and got the cost items and bill of quantities at the same time. The effort and entailing cost of updating the specification of work is lowered and allows an overview over the quantities already in the early phases of the project.
"We were able to identify where we need openBIM to develop further."
The above presented workflow paves the way to implement additional openBIM standards with IFC 4.3 being the most obvious. We used the Norwegian standard specification texts as a classification to map work processes to model entities. However, other national or international classification systems could be used like CoClass, Uniclass, Omniclass or DIN276. Automatic quantity takeoff is defined as a buildingSMART BIM use case leading up to the definition of an IDM and MVD. Our research contribution was the testing of the workflow in a real-life infrastructure project.
Stakeholders
Norwegian University of Science and Technology (NTNU), Trondheim,
https://www.ntnu.edu, Research partner, Eilif Hjelseth
COWI, Bergen,
https://www.cowi.com, Design consultant, Tormod Gulichsen
Norwegian University of Science and Technology (NTNU), Trondheim,
https://www.ntnu.edu, Research partner, Ola Lædre
