The Challenge
A leading civil engineering firm embarked on an ambitious £250 million infrastructure project. As the project scale grew, the firm faced significant challenges with contractor and subcontractor payment disputes. Payment delays and disagreements became frequent, straining relationships and threatening project timelines. Traditional payment processes couldn't keep up with the complex layers of transactions and approvals inherent in such a large-scale project. The engineering firm needed a reliable solution to streamline payments and maintain transparency to ensure smooth project execution.
The Solution
Adyantrix stepped in to provide a cutting-edge blockchain payment solution specifically tailored for the construction industry. Our team developed a blockchain-based system utilising smart contracts to automate and secure payments between contractors and subcontractors. By leveraging the immutable and transparent nature of blockchain technology, all transactions and payment terms were recorded on the ledger, accessible to all parties involved in the project.
Smart contracts were set up to trigger payments automatically upon the completion and verification of specific project milestones. This eliminated the need for manual intervention, effectively removing the bottlenecks usually associated with payment processing. In addition, the blockchain system provided real-time tracking of funds, which enhanced the transparency and accountability of all financial transactions throughout the project lifecycle.
Key Results
The implementation of the blockchain payment solution resulted in a drastic reduction in payment disputes, from an average of 20 payment-related complaints per month to less than 2. The time it took to process payments decreased by 70%, enabling subcontractors to receive payments faster and with higher accuracy. Consequently, subcontractors reported increased satisfaction due to more predictable cash flow and reduced downtime waiting for payment approvals.
Moreover, the construction company observed a 50% increase in project productivity. By eliminating payment-related administrative tasks, project managers could focus more on core construction activities, ensuring the £250 million project stayed on track and within budget.
Adyantrix's blockchain solution not only resolved the existing payment disputes but also set a new standard for transparency, trust, and efficiency in the construction field. The success of this implementation showcases the profound impact of blockchain technology in transforming traditional construction payment processes, providing a scalable solution for future projects of any magnitude.
Technical Approach
The system was built on a permissioned Ethereum-compatible blockchain using the Hyperledger Besu client, deployed within a private consortium network shared between the main contractor, tier-one subcontractors, and the project's quantity surveying firm. A permissioned network was chosen over a public chain for three reasons: transaction finality speed (sub-3-second confirmation), governance control over network membership, and the confidentiality of payment terms that were commercially sensitive between parties.
Smart contracts were authored in Solidity and compiled against the EVM bytecode specification. Each payment contract encapsulated the following logic:
- Milestone definitions: Encoded as a struct containing milestone ID, description hash (SHA-256 of the scope document), completion criteria, and the corresponding payment amount in GBP-pegged stablecoin equivalents.
- Verification oracle: A two-of-three multi-signature approval mechanism required sign-off from the site supervisor, the QS representative, and the subcontractor's own authorised signatory before a milestone triggered payment.
- Dispute escalation: A 72-hour challenge window post-approval allowed any party to flag a dispute, automatically pausing the payment and routing the contract into a mediation state governed by a separate arbitration contract.
Off-chain integration was handled via a RESTful API layer (Node.js / Express) that connected the blockchain contracts to the contractor's existing Oracle-based ERP system. This meant project managers continued to work within familiar software — the blockchain layer operated transparently behind the existing UI, surfacing only when a dispute flag was raised or a payment confirmation was needed.
A React-based subcontractor portal provided real-time payment status visibility to all 47 subcontractor organisations on the project, each authenticated via hardware wallet credentials issued at project onboarding.
Implementation Highlights
Deploying blockchain infrastructure on an active £250 million construction project required careful management of both technical and human factors.
Onboarding 47 subcontractors to a new payment mechanism was the most significant adoption challenge. Many were small to medium enterprises with limited technical capacity. We designed a streamlined onboarding flow that abstracted all wallet management behind a mobile-first web portal — subcontractors never needed to manage private keys directly. Hardware security keys (YubiKey FIDO2) were couriered to each firm's authorised signatory, reducing the credential management burden whilst maintaining cryptographic security.
Integrating with legacy ERP systems required mapping the contractor's existing WBS (Work Breakdown Structure) codes to the smart contract milestone schema. This was a non-trivial data transformation exercise: the ERP held over 2,800 individual cost codes across the project, which were rationalised into 340 payable milestones for the blockchain contracts. The rationalisation was conducted in partnership with the QS team over three weeks.
Regulatory compliance under the Construction Act 1996 (as amended) required that the payment mechanism preserved the subcontractors' statutory right to adjudication. Legal counsel reviewed the smart contract logic to confirm that automated payment triggers did not inadvertently waive any party's rights under the Act. The dispute escalation contract was specifically designed to preserve these rights in code.
Pilot phase: The system was piloted with five subcontractors across two work packages (groundworks and structural steel) before full rollout. The pilot ran for eight weeks and processed 63 milestone payments totalling approximately £4.1 million without a single dispute reaching the escalation stage.
Measurable Outcomes
The headline figures — disputes falling from 20 per month to fewer than 2, and payment processing time cut by 70% — understated the broader operational transformation.
Before deployment, the contractor's commercial team spent an estimated 18 hours per week resolving payment-related correspondence and preparing dispute documentation. Post-deployment, this fell to under 3 hours per week — a productivity recapture equivalent to roughly 0.4 FTE redirected to value-adding commercial management tasks.
Subcontractor cash flow predictability improved substantially. A post-implementation survey of participating subcontractors showed that 89% reported improved confidence in payment timing, and 76% indicated they would reduce their contingency pricing on future tenders with the same contractor as a direct result. The commercial implication for the main contractor was significant: if subcontractor tender premiums for payment risk reduced by even 1–2% on future projects of this scale, the system cost would be recovered on a single subsequent project.
Payment processing costs also fell. Eliminating manual payment approval chains, bank transfer reconciliation, and paper-based application processing reduced the administrative cost per payment transaction from an average of £340 to approximately £42 — an 88% reduction in per-transaction overhead.
Lessons Learned
Smart contract logic must be audited by construction law specialists, not just developers. The first draft of the milestone verification contract assumed that QS sign-off was both necessary and sufficient to trigger payment. Legal review identified that under the Construction Act, withholding notices required specific procedural steps that the contract did not encode, which would have exposed the client to statutory adjudication risk. Involving specialist construction lawyers from the outset of contract design — not as a final review step — is now a standard requirement in our blockchain delivery methodology.
The dispute mechanism is as important as the payment mechanism. Early user testing with subcontractors revealed anxiety not about receiving payment, but about what happened when they disagreed with a milestone assessment. Investing significant design effort in the dispute and mediation flow — making it transparent, time-bound, and auditable — was essential to achieving buy-in from smaller subcontractors who were understandably cautious about ceding control to an automated system.
Permissioned blockchains are the right choice for B2B construction payments. Public chain gas costs, transaction throughput constraints, and the impracticality of managing wallet security across dozens of SME subcontractors would have made a public blockchain deployment unworkable at this project scale. The consortium network model provides the transparency and immutability benefits of blockchain whilst retaining the governance controls that commercial construction relationships require.
Why This Approach Worked
The fundamental reason this solution succeeded was that it addressed the root cause of payment disputes rather than their symptoms. Traditional approaches to dispute reduction in construction focus on contract wording, adjudication procedures, or relationship management — all of which operate after a dispute has already formed. This system prevented disputes from forming in the first place by making milestone completion and payment entitlement objectively verifiable on a shared, tamper-proof ledger.
When every party can see the same payment status, the same milestone evidence, and the same approval history in real time, the informational asymmetry that typically gives rise to disputes is eliminated. Subcontractors could no longer be told a payment was "in processing" with no visibility into where in the approval chain it sat. Main contractor administrators could no longer lose paperwork or delay approvals without it being visible to all parties. The blockchain did not change contractual obligations — it made the fulfilment of those obligations transparent and automatic, which is precisely what the construction supply chain has lacked for decades.
Speak with our Custom Software Development team at Adyantrix to find out how we can support your next project.
Work with Adyantrix
If you are looking to tackle a similar challenge, Adyantrix has the expertise to help across the full project lifecycle. Our custom software development practice covers tailored applications built to your exact workflows. Our blockchain & Web3 practice covers smart contracts, dApps, and tokenisation. Our IT consulting practice covers technology strategy, architecture review, and digital transformation advisory. Our smart contract development practice covers audited Solidity and Rust contracts across EVM chains. Get in touch to discuss your requirements — no commitment required.
