Is it illegal to hit the Extended Stop Arm?  Yes, the extension arm and sign is part of the school bus.  If the arm is hit, law enforcement should be notified and standard accident procedures should be followed.

Is the school or transportation contractor liable for damages caused by a motorist that hits the Extended Stop Arm? The West Virginia Department of Transportation, Indiana Attorney General, and North Carolina Department of Justice have determined that it is illegal for any other vehicle to occupy the area in which the Extended Stop Arm extends. The offending vehicle is liable for damages to the sign or bus as well as their own vehicle.

Does the second sign meet Federal Specifications? Yes, the National Highway Transportation Safety Administration Chief Counsel has stated that Extended Stop Arms meet all the requirements for School Bus Stop Arms (FMVSS 131).  

Is this product legal to install in my county?   Your particular state director of pupil transportation (or equivalent) should be contacted to ensure their approval.  As of January 7th, 2020, the product is installed on 900 school buses in 17 state at 75 school districts.  Approximately 70,000 students ride buses equipped with Extended Stop Arms.

Does the arm impede traffic?  At first glance, it would seem so, but after examining the situation further, it is clearly No.  Once the red lights of a school bus are activated, there is no longer any legal “traffic” around the bus.  In fact, law enforcement officers would issue a ticket to any vehicle that was moving next to a parked bus with their lights on.  This is similar to a road cone placed in the street during road work.  It isn’t impeding traffic, it is notifying the drivers that it is illegal to drive through the work zone while workers are there.

Does the Extended Stop Arm count as an additional arm?  NHTSA Chief Counsel has stated that the Extended Stop Arm is considered a driver side stop arm even though their may be two stop signs in that area.