A giant snake rattles above

...Spewing black clouds into your kitchen"

Shes talking about railway cars and trams.

A little history on railways in Chinatown
The Central Pacific Railroad Company was established, and construction of the route East from Sacramento began in 1863. Although the beginning of the effort took place on relatively flat land, labor and financial problems were persistent, resulting in only 50 miles of track being laid in the first two years. Although the company needed over 5,000 workers, it only had 600 on the payroll by 1864.

Chinese labor was suggested, as they had already helped build the California Central Railroad, the railroad from Sacramento to Marysville and the San Jose Railway. Originally thought to be too small to complete such a momentous task, Charles Crocker of Central Pacific pointed out, "the Chinese made the Great Wall, didn't they?"

The first Chinese were hired in 1865 [sic] at approximately $28 per month to do the very dangerous work of blasting and laying ties over the treacherous terrain of the high Sierras. They lived in simply dwellings and cooked their own meals, often consisting of fish, dried oysters and fruit, mushrooms and seaweed.