Racing Times to be converted into seconds by formula

Hello Xlers,
I face the issue that my racing times found in columns "I" to "M" are not always in the right format.
I need all columns in seconds.
In example: cell I2 shows the number: 01:32:44.010 (1 hour: 32 minutes: 44 seconds and 010 hundredths of a sceond). I need it in seconds which will be : 5564.010 seconds
Which function or formula can do that?

My original file consist of 60,000 lines and growing.

I attach a sample file and hopefully someone can help me to have those 4 columns being revised into "seconds", showing me the correct function or formula.

Thank you very much
Thomas