The state of California in the USA is about to begin construction of a high speed rail line that will go from San Francisco to Los Angeles in 2 hours and 40 minutes. By 2030, the 220mph high speed trains are expected to carry up to 100 million passengers per year, and will be a far faster and more convenient method of travel than flying or driving, meaning people really will want to travel this way.
Even with normal bullet trains, the emissions reduction caused by people taking the train rather than flying or driving would be huge, but this project could be even more positive. Before the project was given the go ahead by the state, the board decided to power it entirely with renewable energy, meaning the already more efficient system could have significant environmental benefits for the state.
The majority of the environmental impacts come from building and maintaining the system itself, but a study from earlier this year shows that overall it's by far the greener option. However, a group of California farmers recently hoped to halt work on the plan over supposed environmental concerns, but from what it sounds like, the only thing they're concerned about is their ability to grow their businesses. That's their prerogative, but claiming they are fighting for the environment when they're trying to stop something that could significantly reduce emissions is ludicrous.