Google Map Traffic Overlay on Android Device

I am currently doing an android project that shows live traffic congestion report. I am a newbie in Android Dev. I successfully deplayed Google map on my emulator. I also did some over开发者_高级运维lay control. I would like to do something like Google did, highlight the road with red (congested), orange (moving slowly) and green (moving swiftly) on the road to show traffic. Any references or any idea on how to add those in Google map? Any help would be appreciated =)

You can use mapview.setTraffic(true); method