LAS Controller described a near runway intersection error; involving traffic landing Runway 19L and a departure from Runway 25R; the reporter alleging flow time pressure contributed to the event.

Narrative

Local Control 1 (LC) had 2 aircraft in position ready for departure on Runway 25R; one of which had a flow time. I (LC2); had Aircraft X on approach for Runway 19L. I knew LC1 was trying to meet the required flow time for their aircraft; so I told Aircraft X to square his turn to final and reduce to final approach speed. LC1 coordinated the runway intersection to me behind Aircraft Y. Aircraft Y started take off roll late; I knew it was going to be close if Aircraft Y was able to clear the intersection before Aircraft X crossed the landing threshold. The Supervisor was also aware of the situation; and the decision was made to let Aircraft X land. Aircraft Y was airborne passing Taxiway A7 (about 800'-900' before the runway intersection) when Aircraft X crossed the landing threshold. Recommendation; ambitious flow times by TMU cause controllers to push aircraft out of tight departure holes when they normally would wait. The layout of the airport causes a huge conflict at the runway intersection. This will never go away and will continue to happen unless we can get the 'GAST tool' back; which allows this exact situation to become a legal operation.