(a) Must drive in a careful and safe manner at all times;

(b) Must comply with the signals and directions of Federal police officers or other authorized individuals;

(c) Must comply with all posted traffic signs;

(d) Must comply with any additional posted traffic directives approved by the GSA Regional Administrator, which will have the same force and effect as these regulations;

(e) Are prohibited from blocking entrances, driveways, walks, loading platforms, or fire hydrants; and

(f) Are prohibited from parking on Federal property without a permit. Parking without authority, parking in unauthorized locations or in locations reserved for other persons, or parking contrary to the direction of posted signs is prohibited. Vehicles parked in violation, where warning signs are posted, are subject to removal at the owner's risk and expense. Federal agencies may take as proof that a motor vehicle was parked in violation of these regulations or directives as prima facie evidence that the registered owner was responsible for the violation.