Transport and sustainability

Order from lowest to highest environmental impact per person on an urban journey and justify the order: single-occupancy car, bus, bicycle and underground.

Rank these transport energy sources from lowest to highest emissions when driving/moving and justify the order: petrol, electricity from renewable sources, diesel and human power (bicycle).

A city bus consumes the equivalent of 8 litres of diesel per $100\ \text{km}$ and carries an average of 20 passengers; a car uses 6 litres per $100\ \text{km}$ with a single occupant. Calculate the consumption per passenger per $100\ \text{km}$ in both cases and comment on the result.

The graph compares CO₂ emissions per passenger per kilometre for various modes of transport. Calculate the emissions for travelling to school and back ($15\ \text{km}$ in total) by car and by bus, and state how many times more one option emits compared to the other.

Twenty students who travel $4\ \text{km}$ a day by car to get to school decide to switch to cycling. With these figures per passenger: $120\ \text{g}$ of CO₂ per kilometre by car versus $0\ \text{g}$ by bike, calculate how many kilograms of CO₂ are avoided in a month of 20 school days.

The construction of a 400 km high-speed railway line has generated a carbon footprint of 1,5 million tonnes of CO₂ equivalent due to earthworks, tunnels, and concrete work on viaducts. In that corridor, travelling by plane emits 120 g of CO₂ per passenger·km, while the train emits 24 g of CO₂ per passenger·km with the current electricity mix.

1. a) Calculate how many full passenger trips by train (replacing the plane) are needed to offset the initial impact of the infrastructure.
2. b) If the line carries 3 million passengers per year and 70 % of them shift from flying, predict in how many years the environmental payback of the project will be achieved.
3. c) Justify how this payback period would change if the country's electricity mix shifted from 50 % to 90 % renewable generation.

Explain what a "protected cycle lane" is and why it increases bicycle use much more than a simple line painted on the road.

What is an "intermodal" journey? Describe a realistic example of a journey to school combining cycling, taking the train and walking, and what is needed to make that combination convenient.

Name three non-environmental benefits of walking or cycling to school (health, financial savings, independence) and explain them in one sentence.

Explain what sustainable mobility is and mention three specific actions a city can take to promote it.

A mobility audit at your secondary school (600 students) reveals that 45 % arrive by private car (with an average occupancy of 1,1 students/vehicle), 30 % by bus, and 25 % on foot or by bicycle, causing severe traffic jams and hazardous situations at the gate at 8:00.

1. a) Design a school mobility plan with three specific technical or organisational measures aimed at reducing car trips by at least half within one school year.
2. b) Define two verifiable quantitative indicators (specifying their calculation formula and unit of measurement) for the school management to evaluate the plan's effectiveness on a monthly basis.
3. c) Justify a low-cost physical intervention on the public street in front of the school (tactical urbanism) that increases the safety of students who commute actively.

A secondary school with 800 students obtained the following percentages in its transport survey:

• Mode A (Active mobility: on foot, bicycle, or non-motorised scooter): 30 %

• Mode B (Public transport: school bus or city bus): 40 %

• Mode C (Carpooling with 2 or more students): 10 %

• Mode D (Individual private car with 1 student): 20 %

1. a) Design a mathematical formula to obtain a "Mobility Sustainability Index" ($I_{SM}$) that scores from 0 to 100. Assign a weighting coefficient between 0 and 1 ($P_A, P_B, P_C, P_D$) to each mode, justifying the chosen values based on their energy efficiency and public road occupancy.
2. b) Calculate the current value of the school's $I_{SM}$ with your formula.
3. c) If the school installs lockers and covered bike racks, managing to get half of the students who came by individual car (Mode D) to switch to active mobility (Mode A), calculate the new index and predict how many cars per day will stop congesting the school entrance.