Cambridge: right-sized for Light Rail…?
According to the International Association of Public Transport (UITP), Light Rail is ideal for carrying 3K to 11K passengers per hour per direction.
Based on our calculations of approximate peak demand in 2011, that is 7281 journeys per hour +285 tourist journeys per hour, this would result in a total of 7566 passengers per hour on the system, or about 3783 per hour per direction, which is above the lower end of the range assessed by the UITP as ‘ideal’ for Light Rail. The demand projected in 2031, including with the proportion of people taking public transport increasing to around 15%, would be 16 108 journeys per hour with ~336 tourist journeys per hour, or in total 16 444 journeys per hour, which places it at ~8222 journeys per hour in each direction, in the mid-range of the UITP ‘ideal’ bracket for light rail. Because light rail can carry many times more than this number, the Light Rail approach would be scalable for expansion and thus future-proofed.
These back-of-the-envelope figures, while perhaps interesting, are inadequate to reach proper judgement. They take no account of demand that would be manifest when a system would be operational from 2032-40 and beyond, which are relevant considerations because the transport network as designed and built over the next 10 years would remain in place for at least 20 years beyond commissioning.
The intent of our work thus far has been to provide some broad guidance on numbers, based on existing data and educated estimates. However, we recognise there is a need for a detailed scientific evaluation of passenger numbers, including of projected and latent demand, and we call for this as part of the full technical and economic feasibility studies we recommend.