A look at BART's overnight testing of new train cars

We're getting a look at some important overnight testing that BART has been doing on the first of its brand new train cars.

BART is trying to replace its aging fleet of train cars as soon as possible, and it won't be long until we're seeing some of those new cars rolling down the tracks. 

Early Friday morning we got a look at some critical testing that's being done on the first 10 pilot train cars. 

We watched as the brand new train left the maintenance yard in Hayward and took a trip across the Bay to the Colma Station and then returned. 

For the past few months BART has been testing this first batch of new cars during the overnight hours when there are no other passenger trains in service. But in a few weeks you might start seeing these new cars cruising along during regular service hours. 

"Once we complete the overnight testing we're going to begin testing during the daytime during passenger train service so these out of service test trains will run in between the trains that are carrying passengers," said BART spokesman Jim Allison.  

BART is doing dozens of tests on these new rail cars, checking the brakes and making sure they can pull other cars if they become disabled. 

BART has ordered a total of 775 new cars to replace the entire existing fleet.