To fix the problem of solid obstacles - bollards, styrofoam signs, corner yardage signs, etc. go to hardware_settings_config.xml file which can be found in:
\My Documents\My Games\FormulaOne2011\hardwaresettings\hardware_settings_config.xml
Edit this file to change the following parameter from false to true:
physics environmentalDamage="true"
\My Documents\My Games\FormulaOne2011\hardwaresettings\hardware_settings_config.xml
Edit this file to change the following parameter from false to true:
physics environmentalDamage="true"