CITY

Subway (Metro) and heavy rail

Subway or heavy rail systems are appropriate for rapid transit corridors requiring very high capacity, typically more than 30,000 passengers per hour per direction. Trains can typically reach speeds of 80 km/h, but because they stop at every station, the average operating speed between origin-destination pairs is usually between 35 and 45 km/h, depending on the distance between successive stations. However, both the up-front investment of over 40 million USD per km and the high operating cost – which usually requires a subsidy – make subway systems unviable for most medium-size cities or those with budget constraints.

Light Rail

Light rail systems, in general being one level below heavy rail or subway systems in terms of both capacity and investment, are certainly appropriate for many rapid transit corridors requiring trunk line capacity. Operating speeds can be similar to those of subway systems or can be significantly lower if many at-grade crossings are present. The up-front investment required – over 25 million USD per km – coupled with high operating costs, still implies a very high level of public investment and often government-subsidized operation. This can be an obstacle for implementation in states or cities with limited budgets, or where current transport operators (competing conventional buses or vans) would need to be removed to ensure light rail ridership.

Monorail

Monorails are appropriate for corridors requiring a capacity of more than 20,000 passengers per hour per direction, where the existing transportation infrastructure at ground level is very saturated. They present a contemporary image, but they also require an investment of more than 20 million USD per km. Depending on the specific technology used, their implementation can be restricted to one-way loops.

BRT (Buses on exclusive lanes)

Bus Rapid Transit has the best capacity to investment ratio and is the most appropriate transport mode for those corridors where there is sufficient space at ground level and where it is viable to convert mixed traffic lanes to dedicated bus lanes without strangling the corridor. BRT systems are typically operated at a profit without subsidies, and this facilitates their implementation in cities with pulverized conventional bus concessions, because the same operators that served the route under the individual owner-operator model can continue to do so under a more efficient enterprise model. Average speed, however, is often only around 20 km/h due to street intersections..

Aerial cars or gondolas

Aerial trams or gondolas are appropriate as feeder systems that serve mountainous sections of a city or areas with very difficult access, especially where the social benefit of serving a vulnerable population justifies the investment (which is high considering the relatively low number of passengers such a system manages to move). In cities with extreme topographies, aerial trams or gondolas can be a vital element of an effective rapid transit network. Where not dictated by topography, however, due to their operating speed below 25 km/h and their capacity below 5,000 passengers per hour per direction, aerial trams or gondolas are not the most appropriate solution for rapid transit trunk lines.

Trams

Modern trams can reach capacities similar to those of BRT systems, and because they operate at surface level the initial investment required is moderate (typically around 15 million USD per km). They can be integrated nicely into the urban environment, including pedestrian zones. However, their operating speeds remain below 20 km/h, so in most cases they are not considered rapid transit.

GRT (Autotrén)

In places where it is necessary to invest in new infrastructure, either elevated or underground, or wherever rights of way are very restricted, modern GRT systems like Autotrén are a more economic alternative in comparison to conventional rail systems or to elevated/underground BRT systems, and they still offer trunk-line capacity of 10,000 passengers per hour. Autotrén’s low operating costs, similar to those of operating conventional city buses in Latin America, coupled with its capacity to attract ridership through high operating speed (around 40 km/h between origin-destination pairs) and guaranteed seating even during rush hours, enable public-private investments and profitable operating concessions.

In medium sized cities without an existing rapid transit network, where conventional rail systems would require unnecessarily large infrastructure or be economically unviable, Autotrén lines can be implemented to form the structural axes and/or rings of a new rapid transit system. In large cities with existing rapid transit networks, Autotrén lines can be used to add important missing links that are difficult or impossible to implement with other technologies. As an added benefit, implementation of the Autotrén system can free up space at ground level for pedestrians and cyclists.