The other half is two lanes, and fairly narrow. But there's not much reason to take it. There's a walkway on the west side. This runs between the South Side and Second Avenue east of Downtown. It's four lanes, concrete, not really any shoulder, but with sidewalks.
Traffic is usually pretty light.
Birmingham Bridge I've started using this bridge more now that the Beehive has opened up on the South Side. It connects Oakland and the South Side, and it's probably the best of the Mon bridges in the city for bikes. It's a smooth concrete 4-lane bridge, with a wide shoulder. If you're crossing over from Fifth, watch for cars merging from Forbes from an on-ramp to the right. The slope is gently downhill towards the South Side.