Which Pittsburgh bridge should be added to the science center's miniature railroad? Voting now open

It's time for the Kamin Science Center's miniature railroad to get a little bit bigger, and Pittsburghers can vote for which addition they want to see next. 

This year, voters can choose between three of Pittsburgh's iconic bridges. Votes can be cast once a day online through July 31, and visitors can use their admission wristbands as ballots when leaving the museum.

First up on the ballot is the 143-year-old Smithfield Street Bridge, which was one of the first bridges in the country to use structural steel in its construction. Up next is the Hot Metal Bridge, which, when it was finished in 1900, allowed locomotives to haul 4,300 tons of molten iron across the river on a daily basis. Last on the ballot is the Panther Hollow Bridge, which has been part of Oakland's Schenley Park since 1896. 

The Miniature Railroad and Village was first displayed at the Buhl Planetarium and Institute of Popular Science in 1954. It was created by Charles Bowdish of Brookville, Pennsylvania, who began building miniature railroad villages in 1919.

Each year, a new model is added to the Miniature Railroad and Village. Last year's addition was the Presque Isle Lighthouse in Erie. It also has tiny versions of Pittsburgh landmarks like the stone chapel in Evans City Cemetery from "Night of the Living Dead," Gus and Yiayia's Ice Ball Cart and Kaufmann's Department Store.