Original: This is due in part to the trains having better performance than the 1967 Tube Stock they are replacing - they have a higher top speed of 80 k , faster maximum acceleration of 1.3 msâ ' 2 , normal service deceleration of 1.14 msâ ' 2 and emergency brake deceleration of 1.4 msâ ' 2 , the same as the 1992 Tube Stock .
Simplified: This decrease is partly because the new trains have better performance that the 1967 Tube Stock that they are replacing . The new trains have a higher top speed of 80 k , a faster maximum acceleration of 1.3 m\/s2 , a normal service deceleration of 1.14 m\/s2 , and an emergency brake deceleration of 1.4 m\/s2 .