Rail way tram

When I am moving in tam on max speed and I press ‘S’ to slow down, tam easly and smooth go slower (even speedometer slowly goes down). When I am moving in reverse gear and press ‘W’ to move forward the train suddenly goes forward, there is no animation.
Somtimes it works… sometimes not.
Video
https://tinypic.com/player.php?v=t9gnki&s=6

the tram has lost its function to move backwards right after a Bullsquid’s soul left its physical body here: bm_c2a2a at: -694 x, -200 y, 818 z
setpos -694.834534 -200.549118 818.752441;setang 22.594141 83.937004 0.000000
the same happens when I just pass the above mentioned creature without hitting it.

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.