CO2 EMISSIONS FROM RAILWAYS – USE OF EMISSION FACTORS

Sudhir Gota

Quantifying emissions from Railways (including LRT/MRT) is really tricky. Some of the variables which often trouble analysts are – use of construction, technology and occupancy factors which can make or break an analysis. Last year, Mikhail Chester brought forward a very interesting analysis on complete carbon footprint of transport modes and this study was critically accepted. The study provided a comprehensive environmental life-cycle assessment of not only vehicle and fuel components but also infrastructure components for automobiles, buses, commuter rail systems and aircraft. Many processes were included for vehicles (manufacturing, active operation, inactive operation, maintenance, insurance), infrastructure (construction, operation, maintenance, parking, insurance), and fuels (production, distribution). The vehicles inventoried in the study were sedans, pickups, SUVs, urban diesel buses, light rail, heavy rail and aircraft.

The important argument made by Chester was that one needs to closely look at the occupancy of Rails and its built infrastructure which often tip the scales. But, more often researchers think that one can always borrow the emission factors from different sources and this would provide some estimates of reasonable accuracy. This is a myth.

In order to demolish the argument of usage of common emission factor, we summarize many of the emission factors [1]available online. The data collation was further helped by inputs from ADB-TA - Reducing Carbon Emissions from Transport Projects.

It is to be noted that emission factors have been quantified using different methodologies with different boundaries. What sets them apart is the huge variation. The variation is between 16 to 1200 g/pkm. The Asian MRT’s which have very high occupancy ratios have values between 20 to 110 g/pkm. Segregating heavy rails, MRT and LRT may help in refining this further. However, it is to be noted that emission factors cannot be constant but dynamic with time in order to reflect changes in design, occupancy and other factors.

Thus, one cannot borrow the emission factor straight away. What one should do is to measure the fuel/electricity consumption to derive emissions. There is no easy way out.

---

[1] Please send us a request in case you would like to access the sources.

Transport Infrastructure Efficiency

Which kind of transport investments are the most efficient?

Sudhir Gota

This question bothers many policy makers. Answering this question is rather difficult as different projects require different scale of investments which carry variable load and satisfies diverse set of consumers. Also it would be wrong to assume that we can always build different alternatives physically having same bunch of people using it.

Knowing the above limitations, we can still assess efficiency of infrastructure requiring different set of investments – from High Cost such as Metro, to median ranged projects such as BRTS, Roads to low cost projects such as bikelanes and footpaths.

Let’s consider the following projects – Metro, BRTS, Expressway of 4 lane, two lane urban in high income zone, two lane urban in Low income zone, Bikeways and Footpaths and thus using the law of averages to evaluate the construction cost efficiency.

In order to compare efficiency – one needs average capacity and average cost. Let’s make an assumption as detailed in below table.

	Capacity (average person/hour)	Cost (million USD)
1 km of Footpath of 2m wide	2400	0.1
1 km of Bikeways of 3m wide	3000	0.15
1km of two lane urban (Low income)	4500	1
1km of two lane urban (high income)	2600	1
1 km of Expressway of 4 lane	8500	3.5
1 km of BRTS	16000	2
1 km of Metro	60000	35

1. The Metro represented here is a replica of Bangalore Metro being constructed now. Its estimated to cost 35 million USD/Km.

2. BRTS – The BRTS taken above satisfies 8000 pphpd and costs 2 million USD/Km. this represents an average BRTS which is being constructed in many Asian cities.

3. Roads are tricky as they can carry a highly variable set of volume. So let’s assume LOS “B” and and 7% as peak hour volume. Lets also assume that a freight vehicle is equivalent to a vehicle carrying 15 passengers. ( this thumb rule matches with Value of time concept)

a. consider 35000 PCU/Day for Expressway – 4 lane

b. consider 15000 PCU/day for 2 lane urban road

c. Occupancy of 1,2,1.5 and 25 for two, three wheeler, car and Bus

d. Assume 50% mode share of freight in expressway and 9% in urban roads ( data Indian Roads)

e. Assume 55% two wheelers in low income and 55% Cars in high income areas

f. The other mode share epitomizes typical Asian roads ( 6% of vehicles as Bus)

4. Use Passenger Car Units to convert PCU’s into vehicles and then using occupancies break down the vehicles into passengers

5. Consider Bikelanes to carry 3000 cyclists/hour suggesting a dense network as seen in Delhi BRTS costing 0.15 million USD/km

6. Consider footpaths to carry 2400 persons/hour at a speed of 1.2 m/sec indicating LOS B. It may cost approx ) 1million USD/km.

Using the same money as required for constructing 1 km metro, one can on an average construct

1. 18 km of BRTS
2. 10 km of four lane Expressway
3. 35 km of two lane urban road
4. 235 km of Bikeways
5. 350 km of footpaths

Thus normalizing different projects into same investment of say 1 km of metro and thus using the capacities and length, we can calculate efficiencies.

The below graph gives the efficiencies

The low cost projects such as bikeways and footpaths in fact provide best efficiency!!

They are 12 to 14 times more efficient than a system like metro. The above calculations can be made more useful by including operation costs and emissions. But the footpaths and bikelanes would be the winners but they often receive least attention and funding.