Quantum expert witness
for construction disputes
Independent quantum expert evidence for international arbitration, adjudication, dispute board proceedings and litigation on construction and engineering projects — prolongation, disruption, acceleration, variations, termination accounts and damages.
Quantum evidence built on
entitlement and records
In construction disputes the quantum case is only as strong as its link to entitlement and to the project cost record. Tribunals are increasingly unwilling to accept global or formula-driven valuations where the records could have supported a more direct assessment. Our quantum evidence is built to meet that standard.
Every head of claim is traced from the contractual basis of recovery, through the cause, to the cost actually incurred or reasonably assessed. Where quantum depends on time, it is tied to the delay analysis — so the tribunal can see why each amount follows from each event. See also our delay expert witness services.
Quantum expert work is led by Metehan Çağlar Sonbahar, a Chartered Civil Engineer with an LLM in Construction Law and Arbitration, who has given expert evidence before the ICC, LCIA, DIAC, ISTAC, ICSID, ITOTAM, DIFC, under the UNCITRAL Rules and in adjudication.
"A quantum figure that cannot be traced back to its cause is a number, not evidence."
We value what the records and the contract support. Where a claimed amount cannot be sustained, we say so early — before it is tested in cross-examination.
Heads of claim
we assess
We act for claimants and respondents, and as single joint or tribunal-appointed expert where required.
Prolongation and time-related costs
Site overheads, preliminaries, extended plant and staff, and head office overheads — assessed from actual cost where records allow, with formula approaches (Hudson, Emden, Eichleay) applied and tested only where appropriate.
Disruption and loss of productivity
Quantification of lost productivity using measured-mile, earned value and other recognised methods, tested against the records for a genuine causal link.
Acceleration
Valuation of instructed and constructive acceleration, including the recoverability of acceleration costs where extensions of time were wrongly refused.
Variations and remeasurement
Valuation of variations, remeasured quantities, rates and prices, cost-plus evaluations and increased costs under FIDIC and bespoke contracts.
Termination accounts and damages
Final accounts, termination valuations, loss of profit and damages for breach, including counterclaims for defects and completion costs.
Review of opposing quantum evidence
Critical review of the other side's quantum report, joint statement preparation, and support to counsel on cross-examination.
Selected quantum
expert appointments
Client names and details are withheld for confidentiality. Further representative matters are shown on our Experience page.
Wastewater line and treatment plant — Middle East
Quantum expert on claims involving variations, remeasurement, cost-plus evaluation, prolongation, preliminaries, increased costs and breach of contract under a FIDIC-based contract.
304 km highway — CIS
Programming and quantum expert in DAB proceedings on an ADB and World Bank-financed highway for an ENR-listed contractor joint venture, with continuing support in the ICC arbitration that followed.
112 km highway — East Africa
Delay and cost expert on an Islamic Development Bank-funded greenfield road project under the FIDIC Pink Book (2010).
Oil processing facility — Eastern Europe
Independent expert opinion on defects, costs and damages prepared during an amicable settlement process.
Port extension project — European Union
Appointed by the Contractor to analyse and value cost and variation claims on a port extension project in the European Union.
Hydroelectric power station — Türkiye
Appointed by the contracting party to provide an independent opinion on cost and variation claims during a formal dispute resolution process on a hydroelectric power station project.
Professional qualifications
underpinning our expert work
Our expert services are led by a practitioner whose qualifications span both the technical and legal dimensions of construction disputes.
Technical foundation across construction, engineering and infrastructure projects — providing the project knowledge that underpins delay and quantum analysis.
Postgraduate legal qualification in construction law and arbitration — bridging the technical and legal dimensions of construction disputes.
Membership of the global centre for dispute resolution practice, reflecting engagement with recognised standards in arbitration.
Member of the Academy of Experts — the UK’s leading professional body for expert witnesses, focused on standards and responsibilities of expert practice.
Postgraduate qualification in construction management providing the project delivery context essential for credible delay and quantum analysis.
Recognised specialist in FIDIC contracts and dispute resolution, including appointments as DAB member under the FIDIC suite.
Quantum expert witness — common questions
What does a quantum expert witness do in a construction dispute?
A quantum expert gives an independent opinion to the tribunal or court on the value of the claims and counterclaims — for example prolongation costs, disruption, variations or damages. The expert does not decide entitlement; the opinion typically values the claim on each alternative basis the tribunal may find.
Do you act for claimants and respondents?
Yes. Equitas acts for contractors, employers and other parties on both sides of construction disputes, and can act as single joint or tribunal-appointed expert where the parties or tribunal require.
Can you review the other side's quantum report?
Yes. We review opposing quantum evidence for methodological errors, duplication, unsupported assumptions and gaps in the cost record, and support counsel in preparing cross-examination.
When should a quantum expert be appointed?
Ideally before pleadings are finalised. Early input shapes how the claim is pleaded and which records are gathered, and avoids a quantum case that cannot later be supported by expert evidence.
Need a quantum expert for a construction dispute?
Contact Equitas to discuss the matter, the forum and the timetable. Initial discussions are confidential.