Drainage Volume
FL Sensor
Description
A "FL" or "flout" sensor measures the volume of water passing through drains in the pavement. Data is automatically collected once every 15 minutes. The Flout (FL) sensor consists of floating container within a 30 gallon collection barrel. As water fills the barrel, the floating container rises until water over-tops an opening in the container. Water then fills the container until the weight of the water exceeds the floating force, which then causes the container to fall and the water exits the system through an outlet in the container. A magnetic proximity sensor is triggered each time the container nears the roof of the barrel. Each time the container falls and empties, 16 gallons is released from the system, and the proximity sensor records the event (as a count).
Manufacturer
This device was designed and manufactured by MnROAD facility staff.
Location and Quantity
FL sensors are located to measure water drained by the curb system (or any water collected after surface clogging) in the pervious pavement cells.
Current Status
The FL sensors continue to function.
MnROAD Database Table
Data has been collected automatically every 15 minutes since the installation of the FL sensors. Data can be found in MnROAD database table: MNR.FL_VALUES.
Tipping Bucket - TB
Description
A "TB" or tipping bucket sensor measures the amount of water draining from the outlet of an edge drain. The Tipping Bucket (TB) device consists of a divided "bucket" and an electronic counting switch. Water from a pavement edge drain falls into one side of the divided "bucket" until it is filled, at which point the bucket tips or "rocks", such that the other side of 8 the bucket then begins to collect the drain water. An electronic switch counts the number of tips of the bucket. Knowing the quantity of water in the bucket and the time between tips, edge drain flow rates can be determined.
Manufacturer
The original tipping buckets (TB) were designed by Mn/DOT and constructed by a consultant hired to manufacture and install the MnROAD sensors.
Location and Quantity
TB sensors are installed at the end of the outlet of edge drains in several MnROAD test cells. ii. There were originally 14 TB sensors located in 5 PCC and 2 hot-mix asphalt MnROAD test cells. Newer test cells have also been equipped with TB sensors.
Current Status
Automated readings from the original TB sensors ceased after June 2003. Sensors in newer cells continue to function.
MnROAD Database Table
Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.TB_VALUES, MNR.TB_ERRORS, MNR.TB_CALIBRATIONS.