Simplify the following text for a Grade 4 native English-speaking person.
Original: In 2008 , the road course was modified to replace the southwest turn with an additional infield section , for motorcycle use , resulting in a 2.621 m course .
Simplified: In 2008 , the road course was changed to add another infield section . This is used for motorcycle racing , and is a 2.621 m course .