Building sustainable urban systems for the future practice questions.

Rotterdam, the Netherlands, has built public squares that are designed to fill with rainwater during heavy storms and to drain slowly afterwards. As a response to climate change, this measure is best classified as:

• Mitigation, because it reduces the greenhouse gas emissions produced by the city
• Adaptation, because it reduces the impact of an expected flood hazard
• Mitigation, because it stores carbon within the urban water system
• Adaptation, because it removes the cause of the heavier rainfall

Answer: Adaptation, because it reduces the impact of an expected flood hazard

Mitigation acts on the causes of climate change, that is on emissions, while adaptation acts on its consequences. The water squares change nothing about emissions but they cut flood damage, so they are adaptation.

The bus rapid transit network of Curitiba, Brazil, in operation since 1974 and upgraded with tube stations from 1991, carries passenger volumes comparable to a light rail line. Which design feature is mainly responsible for that capacity?

• The buses are newer and have larger engines than ordinary city buses
• Fares are subsidised, so more residents can afford to travel by bus
• Segregated busways with level boarding and fares paid before boarding
• Routes share the same streets as cars but are given priority at junctions

Answer: Segregated busways with level boarding and fares paid before boarding

Capacity depends on how fast the buses move and how fast passengers board. A dedicated lane removes delay caused by other traffic, and pre-paid, level boarding cuts the time spent at each stop from minutes to seconds.

Since 2017 Ghent, Belgium, has divided its centre into six sectors and a car-free core: drivers can no longer cross directly from one sector into the next but must go back out to the ring road, while walking and cycling routes stay direct. How does this measure mainly cut transport emissions in the centre?

• By making each vehicle cleaner through improved engine technology
• By charging drivers a daily fee to enter the historic core
• By making short journeys quicker without a car than with one
• By adding road capacity inside the centre so that traffic flows more freely

Answer: By making short journeys quicker without a car than with one

The plan changes the relative speed of the modes rather than the vehicle or its price: driving across the centre becomes a detour while walking and cycling stay direct, so short trips shift mode. Cleaner engines would cut emissions per kilometre but leave the number of car journeys unchanged.

Curitiba in Brazil built a bus rapid transit network with dedicated lanes, level boarding and pre-paid tube stations from the 1970s. What made this attractive as a strategy?

• It delivered metro-like capacity at a fraction of the cost and construction time
• It required no changes to the city's land use planning
• It replaced the need for any other form of public transport
• It was funded entirely by international development banks

Answer: It delivered metro-like capacity at a fraction of the cost and construction time

Segregating the lane and moving fare collection to the station removes the two things that slow buses, so throughput approaches that of light rail without tunnelling. Curitiba also aligned zoning with the corridors, which is why the density followed the transport rather than the reverse.

The Vauban district of Freiburg in Germany combines high residential density, a tram line, restricted car parking and low-energy building standards. Which principle links these measures?

• Density and transport are designed together so that car ownership becomes optional
• Energy standards alone determine whether a district is sustainable
• Restricting parking is effective regardless of what transport exists
• Low-rise, low-density building is required for sustainable neighbourhoods

Answer: Density and transport are designed together so that car ownership becomes optional

Each measure supports the others: density gives the tram enough passengers, the tram makes the parking restriction tolerable, and the restriction frees land for housing and open space. Applying one without the others is where imitation schemes usually fail.

Medellín in Colombia connected steep hillside settlements to the metro with cable cars and built libraries and public spaces at the stations. What was the main intended effect?

• Cutting journey times to work while investing visibly in excluded districts
• Increasing tourist arrivals to the city centre from the airport
• Replacing informal housing with new blocks on the valley floor
• Reducing the population of the hillside settlements through relocation

Answer: Cutting journey times to work while investing visibly in excluded districts

The cable cars addressed a physical barrier - steep slopes made a two-hour journey out of a short distance - and the accompanying public buildings signalled that the districts were part of the city. Accessibility and recognition were the aims, not clearance.