Texas A&M University’s Texas Transportation Institute, contracted by the Texas DOT (TxDOT), installed solar-powered Bluetooth readers along I-35 to provide real-time traffic information to around 30 electronic road signs.

The signs, which are north of Austin and span from Georgetown to Hillsboro, are part of TxDOT’s efforts to provide traffic information to drivers on I-35 during the highway’s construction.

The readers, which were first installed in 2011, pick up signals from Bluetooth-enabled devices, such as cell phones and GPS units, in cars on I-35 and measure the time it takes for the signals to reach the next reader. Times are then sent to monitoring stations and are also communicated through e-mail and Twitter.

TxDOT neither records nor stores personal information from the Bluetooth-enabled devices.

The road signs are temporary and will be replaced with more permanent overhead signs as construction on I-35 continues.