sql server – CONCAT and CASE WHEN combined

I’m trying to create a query that concatenates the directions field that were involved in each transaction_id.

I’ve tried to do it creating a flag table with multiple case whens, and then querying on it, but as you can see in the image below, I’m having trouble to get a multiple 1’s flag in one single row ID.

Any ideas on how to do it?

Here’s the code and the tables I’m using:

SELECT
t2.trans_id,
CASE WHEN t2.dept_nbr IN (SELECT dept_nbr FROM t3 with WHERE dir = 'dir1') THEN 1 ELSE 0 END AS flag_dir1, 
CASE WHEN t2.dept_nbr IN (SELECT dept_nbr FROM t3 with WHERE dir = 'dir2') THEN 1 ELSE 0 END AS flag_dir2 
FROM  
t2

Tables I’m using