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Pset on Alignment2DSegment

Hello everyone,

Customers would like to add Pset on Alignment2DSegment (e.g. Max speed, width, number of lanes…).
For my understanding it is not possible. Pset can be added only on the Alignment object.
Then, is this something that could be considered ?

Thank you,

Hi Kevin,

Alignment2DSegment is a RepresentationItem, in other words, it is geometry. In general in the IFC Schema geometry does not carry semantics. So, you are right, psets cannot be assigned to Alignment2DSegment.

For the purpose of “design parameters” a pset will most likely be assigned to the conceptual model Road or RoadPart classes.

Hi Sergej,

First, thank you for your answer.

I don’t know what is this conceptual model Road or even RoadPart classes…
But is it possible to connect the Pset to the geometry ?

Hi, the support of alignment is new to IFC, first introduced in IFC4.1 and updated in IFC4.2 (currently candidate status). Check technical website for definitions.

In IFC4.1, only the IfcAlignment can hold property sets, where you can add such information for the whole alignment.

In IFC4.2 there is a new entity, IfcReferent, that defines a certain position along the alignment from which onwards certain criteria are applied. You can use this to define a design speed and other criteria.

IFC4.3 (in development) will add additional support for road and railway, this is what @sergej refers to.

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As @TLiebich said there are infrastructure project currently going on to address domain specific issues such as Rail, Road, Water ways, Tunnel etc. You can always join Expert panels to get the in touch and influence the development which is in the first stage in the form of a UML conceptual model. If you are interested in participating I would encourage you to send an email to Infrastructure


Hi Thomas, Sergej,

Thank both of you for your answers.
Indeed it is good to know what are currently in development, I might join the Expert panel, thanks for the advise.