6. The surety shall guarantee payment for any final judgment against the rail carrier for any damage caused in the course of railway activities during the period of validity of the contract, up to a maximum of $5,000,000, per event. Notwithstanding the foregoing, that amount shall be not less than $10,000,000, where the rail carrier transport hazardous substances and not less than $20,000,000, where the rail carrier offers passenger transportation services to the public.