A bill aimed at improving truck and bus safety was approved by the Senate Commerce Committee. The measure, co-sponsored by Sens. John C. Danforth (R-Mo.) and Brock Adams (D-Wash.), would require the Transportation Department to issue new regulations by Sept. 30, 1989, aimed at improving truck brakes, and a department study to be completed by next Sept. 30 would have to consider new anti-lock brake systems used in Europe. It would also require installation of automatic devices aboard commercial trucks and buses to record driving hours and speeds. As many as one-third of drivers are evading federal rules forbidding more than 10 hours of driving at a stretch or a maximum of 60 hours per week, Danforth said. The rules were enacted to reduce the possibility of accidents caused by driver fatigue.