Optimising an air ambulance fleet to complement a ground-based network
When a client comes to us wanting travel radii from their service centres we normally have to caution them about how misleading “crow fly”, or straight line, distance can be in transport planning. So when a project comes along that demands the use of crow-fly distances, it is refreshing. In fact, when an air ambulance charity came to us for help in planning the location of a new operations hub, there was a lot about the project that made it very different to a “typical” network optimisation or site analysis.
The challenge:
One of the UK’s air ambulance charities was looking to increase their coverage by adding an additional helicopter to their fleet. The challenge was in finding the optimum location to base their new air ambulance to complement the existing fleet, so that they could benefit the greatest number of the most vulnerable population. When this was broken down it revealed several distinct sub-challenges:
Complement the limitations of road travel
Although the air ambulance itself can effectively fly in a straight line and land anywhere that the pilot deems safe and is large enough, it is just one part of a holistic emergency network. To work best, it needs to consider road-based ambulances and be positioned to cover the extreme edges of their effective drive radius. So we had to consider a large area in the catchment but factor in an exclusion area close to any hospitals with a trauma centre that could be effectively serviced by traditional ambulances.
An aerial service network based on fixed points and real people
An air ambulance is constrained by having to be based at an existing airfield and needing to get patients to fixed destinations (ie. hospitals). Since creating new airfields or hospitals is out of the question, any network optimisation would need to be a compromise based on the closest viable sites.
With up to 2 hours flight time, at a speed of more than 150mph for each call, and unimpeded by waterways or traffic, the geographic scale of this project was impressive. Population density was a key factor in defining a service area, as it was vital that the helicopter could reach as large a vulnerable population as possible.
Low cost location intelligence for a charity client
Finally, the air ambulance operates as a charity, so our solution needed to be as cost-effective as possible. It costs around £3,000 each time the air ambulance is dispatched, so we needed to ensure that every penny possible went towards saving lives.
The solution:
After discussing the brief with the client, we began the project by undertaking a gap analysis of the charity’s existing air assets. To do this we mapped 60, 90, and 120 miles radius circles from their existing air bases. The critical distance was 90 miles as this marks the optimal maximum radius of a call-out.
We then assigned a nominal value to every person in the overall region and added a value weighting to those people living more than 20 miles from a hospital with an A&E; department. We did this at a postcode sector level to get the right balance between granularity and manageable analysis areas. This gave us a way to account for ground-based ambulance services without excluding the areas entirely, as callouts within this radius could still happen, albeit they are less likely.
Once we had established those clients within the current effective service area, we could identify those outside of this area. Client densities within the unserved postcode sectors could be identified and either mapped or exported.
Finally, new service radii could be overlaid onto the data map from a shortlist of potential airfields, and its impact on the unserved population areas assessed. Charity experts could then create a proposal for a new base that they could then visually share with trustees who would need to sign-off this major investment.
The result:
The location analysis tool for charity customers
All of the work was done within MapVision, our online mapping tool. This brought several benefits to the project that made it the obvious choice.
Ease of data import and export:
Fixed location data such as hospitals and airfields could be imported using either postcode or coordinates as the location key. The population weighting exercise also called for a large amount of Excel work. These spreadsheets could be easily imported into MapVision, mapped, analysed, and then exported again for further manipulation or analysis.
Online collaboration amongst stakeholders:
Like any responsible charity, the air ambulance needed to demonstrate due diligence in such a major decision and engage all trustees and stakeholders in the process. MapVision allows projects to be shared with a wide audience - with any level of technical ability - to illustrate location data, and enable informed decision making.
Cost effective and scalable for charities:
MapVision is far cheaper than a desktop GIS but has all of the tools needed for this kind of location analysis and network optimisation. We offer a significant discount for charity customers. For one-off projects, such as this network analysis, the flexible subscription length of MapVision is perfect. The air ambulance was able to subscribe to the project for just long enough to undertake the analysis, share the results, and make a decision. The end result was the lowest possible cost for effective geographic intelligence.
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