Figure 1.
Statistics of railway bridge infrastructure; (a) according to construction material specifications; (b) according to the number of years in operation (based on [1]).
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.