time different excluding overlap period

If the OP is on an earlier version SQL Server, this version should be good all the way back the SQL Server 2005. ;)

;WITH t AS (SELECT *, ROW_NUMBER() OVER (ORDER BY t.startTime) AS rn FROM @tbl AS t)
SELECT 
        t1.id,
        t1.startTime,
        t1.endTime,
        COALESCE(DATEDIFF(hh, 
                CASE WHEN t1.startTime > t2.endTime THEN t1.startTime ELSE t2.endTime END,
                CASE WHEN t1.endTime > t2.endTime THEN t1.endTime ELSE t2.endTime END
                ), DATEDIFF(hh, t1.startTime, t1.endTime)) AS Diff
FROM t AS t1
        LEFT JOIN t AS t2
                ON t1.rn = t2.rn +1
ORDER BY
        t1.id

---

Jason Long