Final answer:
Abandoning drainage pumps in underground rail systems would lead to severe flooding, infrastructural damage, and potential suspension of transportation services.
Step-by-step explanation:
If hundreds of drainage pumps in underground rail systems like London, Moscow, and New York City were abandoned, the result would likely be severe flooding in the subway tunnels. These networks of pumps are essential for removing water that seeps into the system from surrounding soil, waterways, and rainfall. The London Underground, as an example, dates back to the 19th century with the Metropolitan line, which opened in 1863. Managing water in dense urban environments has been an issue for centuries, evident from London's history of dealing with sewage and reconstructing the sewer system post the Great Stink of 1858 under the guidance of Joseph Bazalgette. Abandoning drainage pumps would also pose significant risks of structural damage to historic buildings due to unchecked water accumulation, much like the sinking issues faced in Mexico City resulting from the depletion of underground aquifers.