 By introducing an advanced drive-time calculation system from MapMechanics, using real-life road speeds to determine catchment areas, retailer ASDA (part of the Wal-Mart group) is improving and speeding up the process of evaluating the market potential for proposed new stores.
Strategic Development Manager Neal Stevenson says, “it is undoubtedly the biggest single development in routing systems t hat I’ve experienced in my career.”
In the past, when ASDA evaluated a potential location for a new or improved store, it used a combination of desktop GIS analysis and a comprehensive catchment visit to assess the quality of the site relative to the strength of the surrounding competitors. Part of the ‘on-the-ground’ catchment analysis also included driving the key roads in the catchment and producing a hand-drawn catchment area which was subsequently digitised into the GIS and the relevant market and demographic data was then analysed. Neal Stevenson explains, “Whilst there have always been GIS systems which are capable of producing isochrones around specific locations, and these are adequate for some uses, we have, however, always had some concerns with the fact that often the isochrones did not always look realistic due to the way the system treated road speeds. As a result we preferred to physically do the drive time research ourselves, for single store decisions, because it was the only way we could be confident of presenting real-world travel time data that would stand up to scrutiny by the Board and our retailers.” The new system developed by MapMechanics, which is called the Enhanced Isochrone Model, calculates drive-times with GeoConcept, the powerful GIS, basing the process on NAVTEQ street-level data with ITIS road speeds. This is a special version of the NAVTEQ dataset, in which each road link is associated with a unique set of speeds for various times of day. The speeds are derived from a massive store of real-world data constantly gathered by ITIS from a pool over 50,000 vehicles in regular service, whose position is pinpointed by GPS (Global Positioning System). “The great thing about this system is that the road speeds are averaged over multiple journeys, so we can be confident that they’re realistic,” Neal Stevenson says. “This is a huge advantage. By contrast, when we actually drive the routes, we’re subject to the vagaries of bad weather, road works, unduly heavy traffic and other local anomalies.” Because the system calculates the exact drive-time along every relevant street, the area picked out may look irregular when plotted on a map; but MapMechanics has done some bespoke programming to create smoothed ‘buffers’ around the areas found. A further attraction of the Enhanced Isochrone Model is that it can calculate drive-times from multiple points simultaneously, whilst still using the real-world ITIS road speeds supplied with the NAVTEQ data. So it is applicable to large-scale analytical exercises as well as one-off projects. ASDA has used other drive-time calculation systems in the past, particularly when it has needed to establish drive-times for many stores at the same time, and when physically driving the routes would have been ruled out by time and cost. “Previous systems have proved acceptable for large-scale, multiple store, exercises” says Neal Stevenson, “but they tend to apply the same road speeds to all roads of the same class in the same geographic region, without reference to any local issues such as traffic lights, congestion hotspots or the time of day. The MapMechanics system takes account of all these factors, so it produces a more precise and detailed result, which is ideal for planning new stores. We will never move away from visiting the site in order to get a qualitative view of the catchment, but with the new system we’re confidently expecting we’ll be able to throw the digitising board away.” He adds: “I’ve been waiting years for a product like this to come along, it’s the future. I’ve never seen an isochrone calculation system that comes anywhere near the accuracy of this one. It produces results that I can confidently put in front of the Wal-Mart Board.” |
