In Back to the Future II (1989), Marty McFly travels through time to October 21, 2015, and discovers the city of the future: holograms, video calls, flying cars, and even hoverboards. At the time, it was considered science fiction, yet it accurately anticipated many of the innovations that would shape the coming decades. While flying cars and hoverboards still sound futuristic, they are getting closer to becoming a reality.

The question of what future cities will look like — and what infrastructures will make them possible — was at the heart of the “Innovative Infrastructures for the Cities of the Future” forum, organized by elEconomista.es. The event featured Telmo Pérez, Chief Innovation and CEO Office Director at ACCIONA’s Infrastructure Division; Julián Núñez, President of Seopan; Isabell Buschel, Founder and Director of Transport & Environment Spain (T&E); Miren Tellería, Real Estate Sector Leader at PwC Spain; and Sonia Suárez, Board Member of the Madrid Association of Civil Engineers.

“When we talk about the infrastructures of the future, we are facing a paradigm shift. The sector will change more in the next 20 years than in its entire history. It’s not just about what we build, or the digitalization and transportation changes — it’s about how we build. This will lead us to an unprecedented level of productivity,” said Telmo Pérez, Director of the CEO Office and Innovation at ACCIONA’s Infrastructure Division. Change will not only come through new infrastructures — existing assets will also undergo significant transformation. “Innovation represents a huge global opportunity. It is driving momentum not only for the creation of new infrastructure, such as data centers, but also for the modernization and adaptation of existing ones,” highlighted Julián Núñez, President of Seopan.

According to Núñez, this second point deserves particular attention: “In Spain, we have a significant stock of public infrastructure. Incorporating innovation into existing and future public works requires modernizing current regulations — innovation in public works depends on regulation.” Building the cities of the future also means driving the energy transition and tackling climate change — and engineers have a critical role to play. “We must design decarbonized cities that improve people’s quality of life, integrate autonomous and connected vehicles, and are resilient to climate change impacts such as floods and droughts. Civil engineers have the expertise to design, build, and manage this type of infrastructure,” explained Sonia Suárez, Board Member of the Madrid Association of Civil Engineers.

For Isabell Buschel, mobility is one of the key areas for improvement: “We need to distinguish between light and heavy vehicles. According to our analysis, Spain’s infrastructure for light vehicles is currently sufficient, but we need to anticipate future growth. There are delays in heavy transport. We must facilitate permits, introduce favorable tax policies, provide purchase incentives, and prioritize the expansion of the electric grid,” she said.

The road ahead is still long. Miren Tellería, Real Estate Sector Leader at PwC Spain, warned that cities are not yet prepared for current demographic shifts: “We are witnessing enormous population growth, and cities are not ready. New neighborhoods are being built just like 30 years ago, with zero integration of new technologies. We’re still building as if it were the 1990s,” she said.

Telmo Pérez (ACCIONA): “When we talk about the infrastructures of the future, we are facing a paradigm shift”

To achieve innovative infrastructures — and, consequently, the cities of the future — we must consider two major transformational forces: digitalization and decarbonization, explained Telmo Pérez, Director of the CEO Office and Innovation at ACCIONA’s Infrastructure Division. “We’re talking about more planned infrastructures that, even if not innovative in themselves, will be in how they are conceived. They will have the ability to digitalize, as new infrastructures will require an interconnected vision,” he said. These advances will lead to a 180-degree transformation in the sector: “When we talk about future infrastructures, we are facing a paradigm shift. The sector will change more in the next 20 years than in its entire history. It’s not just about what is built — it’s about how it’s built,” he emphasized. ACCIONA is already investing heavily in these future-oriented technologies: “We are investors in one of the few existing aerotaxi companies. That futuristic concept already exists and is being tested. In four or five years, people will be using them just like helicopters,” Pérez revealed. However, Pérez stressed that innovation must evolve alongside regulation: “The most urgent issue lies in administrative processes. There are multiple levels of government, each with its own agenda, and that’s creating delays not seen elsewhere,” he noted.

Miren Tellería (PwC Spain): “The urban challenge is regulatory — infrastructure is not keeping pace with innovation”

“We’re experiencing major population growth, yet cities are unprepared. New neighborhoods are still being built with outdated design models, without integrating new technologies. Most housing is privately owned, and homeowners must recognize that residential emissions are a major issue. It’s essential to bring corporate sustainability principles into the private sphere,” she explained.

Sonia Suárez (Civil Engineers Association): “Engineers can provide solutions for innovative infrastructures”

“Civil engineering has the competencies to design, build, and manage this type of infrastructure,” Suárez stated. She emphasized that the priorities must include expanding decarbonized public transport, improving electric mobility, and adapting infrastructure to mitigate climate change. “Progress is being made, especially in urban mobility, and Spain is already a reference in renewable energy and large-scale transport networks,” she added.

Julián Núñez (Seopan): “Innovation in public works depends on regulation — which must be modernized”

“We’ll see a qualitative leap. Autonomous driving will transform mobility habits and reshape public transport demand. Yet innovation in public works depends on a regulatory framework that must evolve. It’s hard to innovate in the 21st century with a framework built in the 1960s,” Núñez remarked. He also stressed that infrastructure must anticipate technological milestones, such as electric mobility, 5G connectivity, and data storage systems, and be guided by public-private collaboration.

Isabell Buschel (T&E): “Decarbonizing through transport electrification is an industrial opportunity for Spain”

“Decarbonizing the economy and reducing energy dependence through transport electrification is not only an environmental necessity — it’s also an industrial and employment opportunity,” said Buschel. She noted that the focus should not be solely on technology but also on replacing polluting fuels: “We’ve reached the limits of internal combustion engine efficiency. The key is deploying charging points, expanding the grid, and developing new synthetic fuels for aviation and shipping,” she explained. “We must remove regulatory barriers, speed up permit processes, and provide incentives for both light and heavy electric vehicles. Infrastructure for light transport is progressing well, but heavy transport remains behind,” Buschel concluded.