Energy and carbon savings with trams – a short paper by Professsor Lewis Lesley
“Getting urban car trips down from 70% to 50% would save about 5% of UK carbon emissions.”
Transport is an energy intensive activity, heavily dependent on oil (99.97%) and a significant emitter of carbon dioxide (30% of UK total). Exhortation and education can reduce car dependency but in the absence of draconian powers to force people to change travel modes, people will freely choosing sustainable alternatives is surely the best way? Market research and behavioural studies demonstrate that for short journeys, under 2 miles (50% UK car trips) walking and cycling are acceptable options, when there are safe and attractive routes. For longer urban journeys ( < 5 miles = 75% of UK car trips) public transport should be the alternative to car ? In the UK most urban public transport is by bus (80% of trips). Car users however are not willing to use buses. Studies by the US Transportation Research Board shows that on a like for like basis of frequency, travel speed, fares etc, buses attract 40% less car users than even old rail services.
Getting car people to use public transport means rail services. Metros and railways would be ideal but most UK towns and cities do not have suitable lines and constructing new lines needs a lot of embedded energy and is very expensive , eg. the proposed London 6 miles long Crossrail will cost £12bn. A former Secretary General of the International Public Transport Association (UITP) observed that light rail gives 90% of the benefits of a metro at 10% of the cost. The speed at which new tram systems have been opened in the UK over the last 20 years, one every 4 years, means that it will take 150years to catch up with Germany. Promoting and funding new tramways is the subject of another paper but given the public funding available, it would probably be better spent promoting cycling and providing cycle networks, and raising the modal split from 2% to 10%, as has been done in Denmark and Germany.
Compared to buses, tram operating along the same route, at the same maximum speed carrying the same passenger loadings will use less than 25% of the energy, which will be electricity, not oil. Indeed I am working on several projects where new tramways will be powered by renewable generation, therefore in energy terms totally sustainable, and almost carbon emissions free, once the embedded energy to build the trams and track have been depreciated, usually a couple of years of operation. Indeed bus operators with routes having a peak frequency of ten buses or more per hour, could already make financial savings in converting to trams. This excludes any carbon emission considerations, and if the new tram service only carried former bus passengers there would only be the energy ( and carbon) savings of trams compared to buses. The real carbon savings come from diverting urban car trips.
New tram systems in France, have attracted 30% more patronage (all car diverted) than the bus services replaced. This is in line with the earlier US study. Car travel is energy intensive, and for short urban trips highly polluting. By suitable park and ride, as well as walk and ride, about 50% of car trips in the tram corridor will be attracted. Getting urban car trips down from 70% to 50% would save about 5% of UK carbon emissions.