is available for calculating the actual mileage between any two locations in the same county. However, for load-distance method, a rough calculation that is either Euclidean or rectilinear distance measure may be used. Euclidean distance is the straight-line distance, or shortest possible path, between two points. A[10, 15) B/30, 10) X Fig. 2.2 Distance between point A and point B The point A on the grid represents the supplier's location in Ghaziabad, and the point B represents the possible warehouse location at Gurgaon. The distance between points A and B is the length of the hypotenuse of a right triangle, or dx = sqrt (X-X) + (Y - Y13 where din = distance between points A and B X = x-coordinate of point A Y = y-coordinate of point A x = x-coordinate of point B Y = y-coordinate of point B x2 Rectilinear distance measures distance between two points with a series of 90 turns as city blocks. Essentially, this distance is the sum of the two dashed lines representing the base and side of the triangle in figure. The distance travelled in the x-direction is the absolute value of the difference in x-coordinates. Adding this result to the absolute value of the difference in the y-coordinates gives DX = X - X, + IYA - Yol CALCULATING A LOAD-DISTANCE SCORE Suppose that a firm planning a new location wants to select a site that minimizes the distances that loads, particularly the larger ones, must travel to and from the site. Depending on the industry, a load may be shipments from suppliers, between plants, or to customers, or it may be customers or employees travelling to or from the facility. The firm seeks to minimize its load- distance, generally by choosing a location so that large loads go short distances. To calculate a load-distance for any potential location, we use either of the distance measures and simply multiply the loads flowing to and from the facility by the distances travelled. These loads may be expressed as tones or number of trips per week. This calls for a practical example to appreciate the relevance of the concept. Let us visit a new Health-care facility, once again. ILLUSTRATION 3: The new Health-care facility is targeted to serve seven censtes tracts in Delhi. The table given below shows the coordinates for the centre of each census tract, along with the projected populations, measured in thousands. Customers will travel from the seven census tract centres to the new facility when they need health-care. Two locations being considered for the new facility are af (5.5, 4.5) and (7.2), which are the centres of censtes tracts C and E. Details of seven census tract centres, co-ordinate distances along with the population for each centre are given below. If we use the population as the loads and use rectilinear distance, which location is better in terms of its total load- distance score? SL No. . Census tract (x ) Population (1) (25.4.5) (25.25) (5.5.4.5) (5.2) (8,5) F (7.2) 7 G (9.25) 14 1 2 B 5 2 3 10 4 D 7 5 E 10 6 20