Well, if at labour prices at half of the US average China can build high speed trains at a fifth of the price that we can build tunnels, there is more to it than that.
Right of way of land works in largely the same way in China than in the US. If you have the 99 year lease for urban terrain, or ownership of rural terrain, the government pays you the amount it would cost for you to buy similar land in the case of rural expropriation, or a market rate for your lease. You are also compensated for improvements to your land, such a crops or buildings. In the case of land owned by collectives, the collective is paid for land value but not improvements, which are paid to the farmer.
In practice, laws are not always followed to the letter, but the same can be said in the US. You have the right to appeal to higher court, which is effective as unless it is a hugely major project, expropriations are generally made by the municipal or regional government.
As for environmental studies, they are directly paid for by the government. Environmental standards obviously vary, but have been strongly strengthened in the recent push against pollution.
