TriMet received some good news from Uncle Sam this morning: $6 million in grant money to help the cash-strapped agency replace a handful of its aging buses. The award, announced by the Federal Transit Administration this morning, comes less than a month before voters decide on a $125 million tax measure also aimed at boosting sagging bus service.

The Oregonian's Joseph Rose was on the conference call where officials made the announcement. The money will be used to replace 14 buses, he reports.

But he also says there's a "catch":

The agency must find 20 percent, or $1.2 million, in matching funds to buy the 14 buses.

If the property-tax measure passes on Nov. 2, TriMet said it will use part of the bond revenue for the matching funds. If it fails, the agency would need to borrow against revenue bonds backed by tax revenues.

Technically, voters are being asked to reauthorize a bond approved in 1990 that's now set to expire in 2012. The tax to pay back that bond would charge property owners $8 per every $100,000 in value on their home.

TriMet's pitch wants you to feel bad for seniors: The elderly and people with disabilities take 10 million trips a year on TriMet—and more and more bus riders will fall into those categories by 2025, officials estimate.