Enhanced urban rail infrastructure
Urban rail systems can come in different forms:
- Heavy commuter rail lines either run on dedicated high-capacity tracks and infrastructure or share the same tracks with other rail services.
- Metro systems are completely segregated from other traffic and provide high frequencies and capacity; they generally have extensive segments either underground or elevated in viaducts.
- Light rail systems typically run on the surface, sometimes including elevated platforms or underground sections; sometimes they share space with cars, buses and other vehicles.
Urban rail allows for, and is especially suited to, dense cities and regions where it can achieve efficiency gains and economic benefits from agglomeration effects. It provides the highest urban public transport capacity, allowing the transport of large volumes of passengers while minimising land use, relieving road congestion, improving local air quality, and reducing accidents and fatalities. It is the only motorised transport mode that is extensively electrified and thus can have zero tailpipe emissions. Urban rail can take particular advantage of the growing share of renewable electric energy as well as from the development of traction batteries and autonomous driving equipment for road vehicles.
For public transport to truly be an attractive alternative to private motoring, and for any notable level of modal shift to occur, it is necessary to improve public transport of an inferior quality to an appropriate service and quality level. The different urban rail systems offer an array of solutions for reliable, frequent, high-quality public transport and high throughput capacity. Enhancing the rail systems’ performance can take place through very different type of investments, from "hard" investment in new infrastructure to, for example, a new traffic management system that improves the capacity of an existing system (e.g. going driverless for metro). In several countries, cities have used investments on a project for a new, modern rail-borne public transport system as an opportunity to redefine goals in terms of urban planning and land use, through the rehabilitation, modernisation or restructuring of the entire urban context.
Where urban rail is electrified, its tailpipe emissions are zero. Climate externalities from electric rail are zero according to the European “Handbook on the external costs of transport”.
By fostering higher-density development, rail indirectly also contributes towards urban forms that favour more public transport use, non‑motorised modes and greater overall transport efficiency. For instance, public transport-oriented compact cities, combined with improved infrastructure for non‑motorised transport, could reduce greenhouse gas intensities by 20-50% compared with 2010 levels. Controlling for other factors, the difference in transport intensity between high- and low-density areas can be more than 40% in vehicle-kilometres travelled per capita.
Passenger rail services will especially contribute to CO2 emissions reductions where load factors are high (i.e. there is sufficient demand) and where electricity powering the rail services stems from renewable energy sources.
The costs of an urban rail project vary greatly according to the type of project, the desired transport capacity and the related infrastructure. While they can have relatively high costs of implementation, they have usually lower lifetime costs per passenger-kilometre than road infrastructure for private cars.
Some reference costs for different systems (per kilometre) that can be identified in the available literature are the following:
- light rail: USD 10 million (US dollars) to USD 25 million
- metro: USD 50 million to USD 350 million
- commuter rail: USD 40 million to USD 80 million.
The average external costs (in euro cents per passenger-kilometre), based on 2016 estimates for the EU28, is 2.71 for electric trains and 3.90 for diesel trains (compared with 19.7 for car travel and 4.8 for bus travel). These estimates include costs for accidents, air pollution, climate change, noise, congestion, habitat damage and well-to-tank emissions.
Urban rail, which often forms the backbone of a city's public transport system, can yield benefits from agglomeration effects. Other gains can include fewer accidents, less congestion and more efficient land use. Rail can also be less noisy than road transport systems.
Rail projects can also contribute to urban regeneration. For example, the opening of Line D of Lyon's metro system quadrupled the rate of urban regeneration in the corridor it served. The proportion of new or renovated buildings for commercial purposes rose to 60% compared with 13% elsewhere.
Because of its capital-intensive nature, urban rail requires very high throughput in order to achieve its environmental and economic goals. Investment in rail infrastructure is expensive, but often provides long-term economic and environmental benefits.
Noise is a consequence of all major modes of transport, and is one of the key concerns for people living near transport infrastructure.
Urban rail infrastructure can lead to separation effects and time losses for pedestrians. It can also be a physical barrier curtailing accessibility to certain urban areas (especially so in the case of surface-level heavy rail commuter systems).
ITF (2021) Transport Climate Action Directory – Enhanced urban rail infrastructure
https://www.itf-oecd.org/policy/enhanced-urban-rail-infrastructure
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