A unique and efficient system model is proposed for sensor networks to create sensor-smart highways. The approach first considers various cell geometries encountered with two-dimensional roads, and then extends the same to three-dimensional roads. Mathematical relations describing each type of cell are derived, and the analyses indicate the numbers and positions of sensor nodes needed in each cell of a certain type. We then propose algorithms for computing the deployment positions of sensor nodes on roads by describing them as consisting of cells of different geometries. We also validate the approach by computing a sensor deployment using real geospatial data.