The second traffic information source is from the Google
Maps real-time and historic traffic information, which
divides an hour into 4 time zones and each time zone lasts
for 15 minutes. The road segment colored in green, yellow,
red or red-black means its driving speed is fast, modest, slow
or congested, respectively. However, Google Maps does not
provide traffic information of all road segments but major
roads in the urban area or highways.