Abstract: A method of assessing whether a vehicle is straddled between lanes (12,14) on a multi-lane carriageway, the method comprising the steps of: a) measuring inductance change values from two adjacent inductive loops (22a, 20b) situated at a loop site, as the vehicle traverses the loop site; b) summing separate logarithms of the inductance change values, or taking a logarithm of the product of the inductance change values, to obtain a value; and c) comparing the value from step (b) against a predetermined threshold value to make a determination as to whether: i) a single vehicle is straddling multiple lanes (12,14), where the value from step (b) is on one side of the predetermined threshold value, or ii) two vehicles are present in adjacent lanes (12,14), where the value from step (b) is on the other side of the predetermined threshold value.

Abstract: A method of assessing whether a vehicle is straddled between lanes (12,14) on a multi-lane carriageway, the method comprising the steps of: a) measuring inductance change values from two adjacent inductive loops (22a, 20b) situated at a loop site, as the vehicle traverses the loop site; b) summing separate logarithms of the inductance change values, or taking a logarithm of the product of the inductance change values, to obtain a value; and c) comparing the value from step (b) against a predetermined threshold value to make a determination as to whether: i) a single vehicle is straddling multiple lanes (12,14), where the value from step (b) is on one side of the predetermined threshold value, or ii) two vehicles are present in adjacent lanes (12,14), where the value from step (b) is on the other side of the predetermined threshold value.

Abstract: Apparatus is disclosed for monitoring use of a carriageway, the carriageway having two or more lanes (12, 14, 16) for use by vehicles travelling in a single direction A, the apparatus including: a pair of inductive loops (20abc, 22abc) on or in the surface of each lane (12, 14, 16), the loops in the pair being positioned substantially side-by-side across the lane (12, 14, 16) and the pairs of loops (18a, 18b, 18c) being positioned substantially side-by-side across the carriageway, each pair of loops (18abc) substantially extending across the full width of the lane (12, 14, 16), and each loop having a length in the direction of vehicle travel which is substantially shorter than the width of the loop across the lane; a loop controller associated with each loop, each loop controller energising its associated loop and carrying out measurements of the inductance of its associated loop; and processing means for receiving the measurements from the loop controllers, and for using the measurements for calculating the

Abstract: Apparatus is disclosed for monitoring use of a carriageway, the carriageway having two or more lanes (12, 14, 16) for use by vehicles travelling in a single direction A, the apparatus including: a pair of inductive loops (20abc, 22abc) on or in the surface of each lane (12, 14, 16), the loops in the pair being positioned substantially side-by-side across the lane (12, 14, 16) and the pairs of loops (18a, 18b, 18c) being positioned substantially side-by-side across the carriageway, each pair of loops (18abc) substantially extending across the full width of the lane (12, 14, 16), and each loop having a length in the direction of vehicle travel which is substantially shorter than the width of the loop across the lane; a loop controller associated with each loop, each loop controller energising its associated loop and carrying out measurements of the inductance of its associated loop; and processing means for receiving the measurements from the loop controllers, and for using the measurements for calculating the

Abstract: Loop sensing apparatus for detecting vehicles traveling along a lane of a roadway comprises an outer loop producing a region of magnetic field with the same polarity and an inner loop sized to fit within this region of constant polarity. The inner loop provides two regions of opposite polarity, so that field produced by the outer loop has a null effect on the inner loop. Detection circuitry energizes both the outer and inner loops individually for separate detection of vehicles passing over the loops.

Abstract: A road vehicle sensor provides an output signal having a magnitude which varies with time through a plurality of values as a vehicle passes the sensor. Signal processing apparatus monitors the timing of sensor signals generated from sensors in adjacent lanes of a highway and provides an indication when such sensor signals could correspond to a double count with a single vehicle being detected by both sensors. Then, the geometric mean of the amplitudes of the sensor signals from the sensors in adjacent lanes is calculated and is used to indicate a double count if the geometric mean is below a threshold value. Signal processing arrangements are also described to detect tailgating vehicles which may be simultaneously detected by a sensor, and for determining the length of slow moving or stationary traffic.