TRM: Vehicle Emissions

=== PART OF TRANSPORT REWORK MOD ===

Every vehicle's noise and pollution come from what it is, not from a hand-typed number.

In the base game a 2014 truck is rated three times as loud as its 1980 predecessor, electric locomotives pollute more than small steam engines, and wagons without an engine get noisier from decade to decade. With this mod both values are derived from the vehicle itself when it is loaded: engine type, power, top speed, weight and year of introduction.

=== FEATURES ===

• Noise from the vehicle. An engine term by type, horse, electric, diesel or steam, plus rolling noise that rises with top speed. Diesel engines get quieter after 1970, vehicles without an engine make rolling noise only and are silent at a standstill.
• Pollution by engine and era. Steam and early diesel engines are the dirtiest, every combustion type gets cleaner over the decades, electric vehicles emit next to nothing and horses a little.
• Fleets stay as loud as before. Within each carrier the fleet as a whole stays as loud as in the base game, so towns are not suddenly quieter. What changes is the difference between vehicles, set to half of the real-world difference. The dirtiest vehicle of each carrier keeps the base game's maximum.
• Civilian traffic. The cars of the residents, rated at a fourteenth of a bus in the base game whatever their age, can follow the same rules as the road vehicles.
• Idle emissions. Road vehicles standing at a stop or a junction can emit less than moving traffic, so queues are quieter and cleaner.
• Other mods and DLCs. Their vehicles are treated the same way, since the values come from the vehicle files rather than from a table.

=== SETTINGS ===

• Vehicle Noise ("Base Game", "Rebalanced", default "Rebalanced"). "Rebalanced" derives the noise value from the engine type (horse, electric, diesel or steam, or the sound set for ships and aircraft), the power or thrust, the top speed, on roads the weight, and the year of introduction. Rolling noise rises with top speed, diesel engines get quieter after 1970, and vehicles without an engine make rolling noise only, so wagons and coaches are silent at a standstill. Within each carrier the fleet as a whole stays as loud as in the base game. Only the differences between vehicles change, set to half their real-world size.
• Vehicle Pollution ("Base Game", "Rebalanced", default "Rebalanced"). "Rebalanced" derives the pollution value from the engine type, the power or thrust and the year of introduction: steam and early diesel engines are the dirtiest, every combustion type gets cleaner over the decades, electric vehicles emit next to nothing and horses a little. The dirtiest vehicle of each carrier keeps the base game's maximum.
• Electric Vehicle Pollution ("None", "5%" to "25%", default "10%"). The share of the pollution of a 1970 diesel engine of the same power that electric vehicles cause, standing in for the power stations that supply them. At "10%" a 4,200 kW electric locomotive pollutes about as much as a 420 kW diesel of 1970. Only applies with "Vehicle Pollution" set to "Rebalanced".
• Electricity Era Effect ("Off", "Low", "Normal", "High", default "Normal"). Whether that share falls with the vehicle's year of introduction as power generation gets cleaner. At "Normal" vehicles from 1950 and earlier get the full share, a vehicle from 1990 gets 70% of it, from 2010 half, from 2030 a quarter and from 2050 a tenth. "Low" halves that decline, "High" doubles it.
• Horse Pollution ("Low", "Normal", "High", default "Normal"). Horses leave manure in the street. At "Normal" a two-horse carriage or horse tram is rated about 3.5 on the 0 to 100 scale and a one-horse cart about 2, roughly half of the first steam trucks. "Low" is two thirds of that and "High" a third more.
• Civilian Traffic ("Base Game", "Rebalanced", default "Rebalanced"). Whether the cars of the residents are rated like the road vehicles. In the base game every car, from a 1900 horse coach to a modern sports car, carries almost the same small value, about a fourteenth of a bus. With "Rebalanced" cars follow the same rules as buses and trucks, so towns with heavy traffic get noisier and dirtier, most of all between 1930 and 1990.
• Idle Emissions ("Base Game", "High", "Normal", "Low", default "Normal"). How much of a road vehicle's noise and pollution is emitted while it stands still. In the base game a waiting bus, truck or car emits 70% of its full value. "High", "Normal" and "Low" lower the standing share to 50%, 30% and 10% of the noise value and to 55%, 40% and 25% of the pollution value, the rest being emitted with speed and engine load. Trams, trains, ships and aircraft keep the base game's split.

=== INGAME EXAMPLES ===

• A 4,200 kW electric locomotive at "10%": the pollution of a 420 kW diesel of 1970.
• A two-horse carriage: about 3.5 on the 0 to 100 pollution scale, half of the first steam trucks.
• A bus waiting at a stop: 70% of its full noise in the base game, 30% at "Normal".

=== COMPATIBILITY ===

The values are set when the game is loaded and nothing is written to the save, so the mod can be added or removed at any time. Vehicles from other mods and DLCs are treated the same way. The game's Noise Sensitivity and Pollution Sensitivity settings and the vehicle maintenance effect still apply on top. Option changes take effect at the next load.