Verifying someone else's design is a different job from producing one. The verifier does not start from a blank sheet; he or she starts from the designer's assumptions, tests whether they hold, and writes down what does not. At Vifatec, a dedicated transport-infrastructure team, led by our Chief Operating Officer, covers bridges (concrete, steel and composite), roads and earthworks, slopes, retaining structures and geotechnics. This article explains how we approach verification on that work, with two examples from our references.

Verification is not a second design

A good verification answers three questions. Are the inputs right: loads, ground data, standards and the project's own requirements? Is the method appropriate for the structure? And do the results reach the drawings correctly? The output is a list of comments that the designer can answer, not a parallel set of calculations for its own sake. Where a result looks doubtful, an independent calculation is made on that point only.

Example 1: a seismic diagnosis of a major bridge

On the Moulay El Hassan bridge in Rabat, our expertise showed that the elastic spectrum used in the execution studies strongly underestimated the spectrum defined by EN 1998-5. Rather than stopping at that finding, Vifatec produced a seismic diagnosis based on post-elastic behaviour: damage is accepted in the plastic hinge zones, while non-collapse is guaranteed.

The scope shows what a verification looks like in practice:

  • analysis of the constructional arrangements in the plastic hinge zones;
  • evaluation of seismic forces with a behaviour factor;
  • acceptability of displacements at the bearings.

Each item is a question a checker can answer yes or no, with a calculation behind the answer.

Example 2: checking execution drawings

On the steel-and-glass canopy of Les Halles in Paris, Vifatec checked the execution drawings in the VISA phase and studied vibration comfort and dynamic effects. Verifying execution drawings is where the design intent meets the workshop: member sizes, connections and tolerances must agree with the structural calculation. The same discipline applies to the connection design we provided on the Laval footbridge and the Brest cable car, two projects where Vifatec delivered structural consultancy and connection design.

Standards and where they apply

A verification is always carried out against a named reference. Our team works with the Eurocodes (EN 1990 to EN 1999, including EN 1997 for geotechnics and EN 1998 for seismic design), French rules and guidance, AASHTO and ACI where the project requires them, and Vietnamese standards and regulations (TCVN, QCVN). The first task of any verification is to write down which standard governs which question, because projects often mix references.

The Vietnamese licence, explained

For work in Vietnam, Vifatec holds a construction activity capacity certificate with Class II for the design and verification of roads and bridges. Vietnam grades such certificates in three classes: I is the highest, then II and III. The certificate shows formal competence recognised in Vietnam. It is not required for work on European projects, and we mention it so that readers can place it correctly. Details are provided to clients on request.

Geotechnics: where verification often starts

Bridges and roads depend on the ground. Our team covers slopes, embankments, retaining walls, anchorages and barrette piles, and geotechnical analysis is part of the verification: what ground data was used, how it was interpreted, and whether the foundation and retaining design is consistent with it. Our technical advisers include a specialist in geotechnics, and we can support geological and topographic survey work.

How we organise a verification

  • Brief. You send the design package and tell us the standards, the scope of the check and the deadline.
  • Reading. The checker reads the calculation notes and the drawings together, and lists the assumptions.
  • Targeted calculations. Independent checks are made where the result or the assumption is in doubt.
  • Comments. Each comment is traceable and numbered, and the issue log is shared.
  • Close-out. Answers are reviewed, revisions are recorded, and the final list is issued.

Our own deliverables follow the same logic: a two-step check, with the author first and an independent checker second.

What to expect, and what not

You should expect a clear list of findings against named standards, written so that the designer can answer them quickly. You should not expect us to replace the responsibility of the design lead or of the project owner: final sign-off stays with the contracting partner.

To discuss a verification package, write to contact@vifatec.com. We sign your NDA before receiving data.