What is the best way for a Project Manager to Build Team Accountability?

As no two teams are the same (unless you are always doing projects with the same team) this really comes down IMHO to building rapport with the individual team members AND build a team spirit towards that total effort that will get the project on rails as well as delivering.

• Individual rapport: You don't need long walks on the beach to get to know your team members but just from a human interest angle, spend a bit of time talking to your team members about things that are not work. Take an actual interest - don't fall into the trap of always asking the same 2-3 fake interest questions but invest in the relationship.
• Team rapport: Team building is almost a cliché - but it is ABSOLUTELY a good idea to do a few social building sessions with everyone. Doesnt need to be complicated - go offsite for some talk on strategy, invite for a mug of tea/coffee/favourite beverage and cake/snacks/whatever works, etc. The goal is comfortability with each other - don't need to end up as extended family, but some familiarity makes things go much easier.
• Clear individual targets: Work with each team member to clarify what they need to deliver, when and map out the activities needed to reach the finish line. Whatever model or practice you work from, establish the critical path on deliveries and work on the focus there.
  If you understand what you are supposed to do, it is much easier to own it.
  That way it also becomes much easier to assist if something or someone is keeping a team member from reaching the targets.
• Group goals and interdependencies: I have seen quite a few teams where everyone keeps being individual contributors and just work in their own siloes, not considering if their work has an impact on other team member's effort - especially if delayed or not delivered to spec. Work with the team to build an overall plan so everyone can see where they fit in and how/when their contribution fits in - when everyone has understanding of the overall goals, that helps too. Make ownership a group goal.
• Scope, scope, scope: A final thing is a clear scope - what is in scope, what is most definitely out and so on. I have recently used the "moscow method" quite successfully because it is a very visual and very simple way to visualizing the overarching goals of the project.When it is clear what needs to be done and delivered overall - that also informs the individual and group accountability in my experience.