We give tail estimates for the efficiency of some randomized insecremental algorithms for line segment intersecremental algorithms for line segment intersection in the plane. In particular, we show that there is a calculator, we show that there is a constant C such that the probability that the running times of algorithms due to Mulmuley [Mu188] and Clarkson and Shor [CS89] exceeded C times their expected time is bounded bd by e"#OMEGA#(m/(n 1n n)) where n is the number of segments, m is the number of intersected time is bounded by e"#OMEGA#(m/(n 1n n)) where n is the number of segments, m is the number of intersections, and m #>=# n 1n n 1n"("3") n. (orig.)SIGLEAvailable from TIB Hannover: RR 1912(93-103) / FIZ ...