Lessons from mapping what lies beneath cities

As cities race to deliver more housing, expand transit, and modernize infrastructure, some of their most consequential innovation is happening not on construction sites but inside the partnerships they're building to manage and share critical infrastructure data.

That’s because local leaders everywhere face a hidden constraint on their ability to build: fragmented data about the so-called “underground assets,” such as unmapped fiber cables, critical gas lines, and collapsed water mains, that lie beneath their streets.  When construction crews unexpectedly encounter these obstacles, it can stall projects, inflate costs, and slow urgently needed development. In Wellington, New Zealand, for example, a 2024 city council survey estimated that inaccurate or difficult-to-access underground data was costing the infrastructure sector tens of millions of dollars each year, as well as thousands of days in delays.

To overcome this barrier, cities across the world are not simply producing better maps; they are redesigning how public and private institutions collaborate. These efforts bring fragmented data into new systems that allow agencies, utilities, and contractors to work from the same information and follow common rules for using it. The immediate product of this work is a unified digital perspective of what lies beneath city streets. But the deeper innovation lies in the coordination and trust making that perspective possible.

Diagnosing a system in need of overhaul.

As with many successful urban innovations, this work began not with technology but with a clear diagnosis of a system that wasn’t serving residents. In particular, city leaders increasingly realized that the way underground infrastructure information was managed and shared across government agencies, utilities, and construction companies was slowing their ability to deliver.

For decades, records about underground assets were scattered across multiple institutions. Some were paper-based, others digitized but stored in incompatible formats. Contractors and engineers often had to assemble their own picture of what lay beneath a construction site by reconciling multiple datasets, many of them incomplete or contradictory.

What cities began to recognize was that this fragmentation was not simply a technical problem. It was a coordination problem. 

And as pressure has mounted to accelerate housing construction in particular, leaders have recognized that better governance of underground data can remove a persistent barrier to building. “We want to build homes faster,” explains Randal Rodger, a civil servant in Ottawa, Ontario, whose team has worked to unify the city’s underground asset information. When infrastructure data is accurate and accessible, developers are less likely to face delays and cost overruns.

Cities are also recognizing the broader benefits of improving how underground information is managed. For example, first responders can better assess nearby infrastructure during emergencies, and planners can design new transit hubs with a clearer understanding of existing utilities.

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Designing incentives for collaboration.

Once they’ve identified key challenges that can benefit from new forms of data governance, cities still need to overcome institutional norms: the hesitation of key actors to disclose everything they know given long traditions of guarding that data internally.

As Fernando Fernandez-Monge, a senior associate at the Bloomberg Harvard City Leadership Initiative who researches data governance, wrote of Wellington’s work to confront this challenge, “This data can be sensitive, both for security reasons and companies’ business interests, so they are not eager to share it.” 

That sensitivity means cities cannot easily mandate compliance or, for that matter, just purchase new software and expect alignment to follow. Instead, they are designing frameworks that make better collaboration possible. 

In Wellington, the city has launched what it calls an underground asset register. It’s essentially a map that consolidates utility operators’ data on pipes and cables into a single, easily updatable platform. And the way they built it was by engaging in a years-long process of stakeholder engagement, informed by their Bloomberg Harvard City Leadership Initiative training, to incentivize key players to share data in unprecedented fashion. 

“People have to trust you,” explains Denise Beazley, a local official leading this work in the city. “They have to have a sense of being part of a team and that they have a legitimate seat at the table and that you understand their needs.”

To build that trust, Wellington officials formed a technical reference group composed of everyone from utility owners to regulators to contractors to surveyors, engineers, planners, and even the people actually drilling on local streets. The goal? Making it clear the city was grounding the effort not just in local leaders’ political priorities, but also in the infrastructure community’s expertise. 

What began to emerge was a sort of FOMO effect, where the city signaled that businesses and other actors might miss out on access to data that could help them meet their own internal goals, such as speeding up projects. This, in turn, incentivized greater participation in the city’s since-launched asset register platform.

“You have to demonstrate value—because their time is money—and help them to understand that there's a benefit to participating,” Beazley says. 

Fine-tuning governance to make the new system durable.

Once cities begin designing more coordinated systems, they can take strategic steps to ensure those relationships endure. 

Sustaining collaborations that are anchored by data requires decisions about custodianship, access controls, and long-term governance. And in the case of underground asset mapping, some of the relevant datasets are operationally critical and even high-risk. Wellington addressed these concerns by appointing a third-party nonprofit as the independent custodian of its new, shared database. “Our role is to be the librarian,” Beazley says of the city. The arrangement reinforces neutrality and reassures participants that no single actor will control or exploit the system.

Ottawa, which has received the Bloomberg Philanthropies What Works Cities Gold Certification for its exceptional data practices, opted to house its asset register within government. “For us, it’s owning the data so that we can harvest it for multiple use,” Rodger explains. By running the system internally, the city aims to leverage underground data across departments and planning processes.

What stands out most about this work is the commitment of local leaders to strengthen the systems that allow data to move across institutional boundaries, including institutions outside of government. Rather than accepting fragmentation as inevitable, they have invested the time and political capital required to build durable collaboration in service of urgent priorities like housing and infrastructure delivery.

That commitment is beginning to reverberate beyond city limits. Wellington’s asset register recently earned a collaboration excellence prize and has drawn praise from New Zealand’s national government, which has highlighted the model as a way to reduce costly project delays and is exploring its potential for nationwide adoption. It’s a reminder that urban innovation is not confined to solving municipal problems. When cities work in new ways, they often create blueprints that reshape practice at higher levels of government.