Leading the way in increasing greenhouse gases
According to the ‘High Speed Rail Industry Leaders Group’, HS2 and Crossrail are leading the way in the vital task of reducing carbon emissions for new infrastructure projects.
[David Shirres, ‘Reducing project carbon’, Rail Engineer, 17 Jan 2017]
Transport for London (TfL) is reducing its contribution to climate change to support the Mayor’s ambition of London becoming a zero-carbon city by 2050. To do this, TfL is taking action to reduce its carbon dioxide emissions by 60 per cent by 2025 (from 1990 levels), including reducing project embodied carbon.
So, TfL are planning to reduce carbon emissions.
But what about HS2?
For Crossrail and HS2, sustainability is a high priority. Considering carbon at the early design stage enables these mega-projects to achieve significant carbon (and cost) reductions for both construction and operation. Crossrail’s operational energy usage will be minimised by a vertical track profile that aids deceleration and acceleration, responsive escalators, specially developed LED lighting and lightweight energy-efficient rolling stock. Crossrail has so far achieved an 11 per cent reduction in embodied project carbon against its baseline. This is mainly due to reduction in construction materials and the amount of cement used in concrete, subject to cement performance requirements and curing time.
Project construction is estimated to generate 1.7 million tonnes CO2e, against which the carbon footprint model indicates annual operational CO2 savings of between 70,000 and 225,000 tonnes, largely due to car journey replacement. Crossrail estimate that, after 9 to 13 years, the project will provide net CO2 savings.
The construction carbon footprint for HS2 Phase One is estimated to be between 5.3 and 6.5 million tonnes CO2e. Some of this is from the construction of tunnels and earthworks as mitigation for environmental noise and visual amenity. Operational emissions are estimated to be a net 3 million tonnes CO2e over a 60- year period taking into account modal shift, mitigation from planting two million trees and freight benefits from released capacity on the classic network. Emissions per passenger kilometre from high-speed rail, inter-city rail, car and plane are estimated to be respectively 8, 22, 67 and 170 grams of CO2e.
49 per cent of the embodied carbon for the construction of a high-speed railway comes from steel while 28 per cent is from concrete. HS2’s opportunities to lower embodied carbon include maximising opportunities to re-use excavated material on site, the use of 4-D modelling to plan efficient logistics with low carbon modes such as rail and development of new materials including sustainable concrete.
In all the verbiage, Mr Shirres never got around to saying whether building and operating HS2 would reduce, or increase, carbon emissions.