Municipal Law | Professional Liability | Civil Infrastructure

This article examines City of Montréal v. Aecom Canada Ltd., a lawsuit arising from alleged design deficiencies in the Pie‑IX Bus Rapid Transit (BRT) project. It explores the allocation of risk in public infrastructure projects, the legal standards for engineering negligence, and the implications of the case for Canadian municipal procurement practices. Montréal’s claim serves as a salient example of a municipality seeking to recover costs attributable to professional errors within a public-private development framework.

1. Introduction

Municipalities across Canada are increasingly turning to infrastructure projects that involve complex coordination among contractors, consultants, and public agencies. The legal exposure of engineering and architectural firms in these projects has grown in parallel with the scale of public investment. City of Montréal v. Aecom Canada Ltd. presents a compelling case study in municipal litigation against a professional services provider, wherein the City alleges that Aecom’s design deficiencies resulted in substantial cost overruns and construction delays on a flagship transit corridor.

2. Factual Background

The Pie‑IX BRT project was designed to create a high-capacity, rapid bus corridor between Montréal and Laval. Initially budgeted at approximately CAD 154 million, project costs exceeded CAD 523 million by the time service began in late 2022. The City of Montréal filed suit in March 2022, alleging that Aecom Canada Ltd.—the engineering consultant tasked with design and specifications—produced incomplete, inaccurate, and negligent work that directly caused construction delays and necessitated significant change orders.¹

Central to the claim is the allegation that Aecom failed to properly locate underground utilities and buried structures. These oversights led to construction delays and additional costs, which the City argues were reasonably foreseeable consequences of professional negligence.

3. Legal Issues

The litigation raises three primary legal issues:

3.1. Professional Negligence

At the heart of the City’s case is a claim of professional negligence. Under Canadian tort law, engineers and architects owe a duty of care to their clients to exercise the skill and diligence expected of reasonably competent professionals in their field.² In Edgeworth Construction Ltd. v. N.D. Lea & Associates Ltd.,³ the Supreme Court of Canada recognized that design professionals may be held liable to both contracting parties and third parties where their negligent misstatements induce reliance and cause harm.

The City contends that Aecom breached this standard by failing to conduct adequate site investigations and utility mapping prior to finalizing design documents. If proven, this could constitute a breach of duty under both tort and contract law.

3.2. Contractual Allocation of Risk

Standard form contracts for engineering services—such as those promulgated by the Association of Consulting Engineering Companies (ACEC) or Fédération des ingénieurs municipaux du Québec—often include clauses limiting liability for unforeseen site conditions. However, such clauses may not protect the consultant where the conduct alleged rises to gross negligence or where contractual disclaimers were insufficiently clear.⁴

Courts have consistently held that ambiguous exclusion clauses are construed contra proferentem, and will not shield parties from liability absent explicit language.⁵ Therefore, the enforceability of any limitation-of-liability clause between Montréal and Aecom will be central to the case.

3.3. Causation and Quantification of Damages

To succeed, the City must prove that Aecom’s negligence was the proximate cause of the extra costs incurred, and not the result of unrelated construction risks, changes in scope, or contractor inefficiencies. Damages must be quantifiable, foreseeable, and supported by a direct causal chain.

This presents evidentiary challenges, as municipal infrastructure projects often involve multiple overlapping causes of delay and cost escalation. The Court may require expert testimony to parse the various factors contributing to the final cost.

4. Legal and Policy Implications

4.1. Risk Management in Municipal Procurement

The Montréal case underscores the importance of robust due diligence and risk allocation at the procurement stage. Municipalities must ensure that contracts clearly articulate responsibilities related to site investigation, utility coordination, and the consequences of latent defects.

Some municipalities have adopted early contractor involvement (ECI) or integrated project delivery (IPD) models to better allocate these risks across the design and construction continuum.⁶ However, these frameworks remain relatively underused in Québec.

4.2. Professional Standards and Municipal Oversight

This case also highlights the growing accountability of engineering firms in the public sphere. With increased public investment in green and transit infrastructure, courts are likely to scrutinize professional conduct more closely.

At the same time, municipalities must recognize their own role in ensuring quality assurance during project design. Passive reliance on consultants without internal vetting mechanisms may limit a city’s ability to claim damages downstream.

Conclusion: Building Bridges

City of Montréal v. Aecom Canada Ltd. represents a significant case in the evolving landscape of professional liability in public infrastructure. As municipalities continue to invest in large-scale projects under fiscal and political pressure, the need for legally sound procurement, oversight, and accountability mechanisms becomes ever more apparent.

If Montréal succeeds, the case may strengthen the doctrinal foundation for municipal recovery in cases of engineering negligence. Conversely, if Aecom prevails, it may reinforce the need for more precise risk management strategies within government procurement frameworks.