Recently I’ve been doing some work involving the transportation problem. The Transportation Problem is an allocation optimisation problem that requires the optimal assignment of demand, in my case patients by Output Area, to known, fixed, supply points, in my case doctors surgeries (General Practices). Rather than use a euclidian or manhattan metric to model distance from the demand site to the supply site I have used public transport travel times from TfL.
Initially this seemed a difficult task, and early attempts only provided partial, or non-optimal, solutions. However, once I had found the linear programming functionality in R through the package LPSolve it became very easy to create a model with the constraints I wanted and get a solution very quickly. Key to the success of the R package was the ability to set the constraints I needed, crucially integer constraints so that people were not subdivided, and constraints on the number of patients doctors could take.
Mapping the outcomes in ArcGIS was straightforward due to R’s built in csv-export funtionality.
Here is an example of the output.
The legend denotes the 44 physical practices in the London borough of Southwark, some doctors exist on the same site and so these practices were agglomerated. The grey areas represent unallocated demand caused by capping the size of the General Practices. In another definition of the model I ran I set the GPs up as uncapacitated so that all the demand would be satisfied. This model uses data from 2006, I have data from 2009 for which I will also run the model.
Some earlier work I did on this is available in the Proceedings of GISRUK ’09.
September 22nd, 2009
by Martyn
I like this map. Would be awesome if you could implement other forms of transport (eg cycle times) and note the differences/optimise time.
January 10th, 2011
by marihot siahaan
Dear Mr Lewis,
we have upcoming workshop on transportation problems in Jakarta Indonesia on this coming June 2011. I established a management training and consultancy, Kemsis International, in Jakarta.
To work together with an Association of Motorbike Users in Indonesia(P2MI), weare now working to organize a symphosium and workshop on the topic of solving the transportation problems in big cities in Indonesia, particularly Jakarta. The Governor of Special Territory of Jakarta together with the central government of Indonesia had expressed their concerns, sometime in frustation, of the very serious transportation problems in Jakarta. So heavy is the traffic and so bad is the public transportation that it takes hours to get to a place of shorter than 10km. In this symphosium – tentatively scheduled in June 2011 in Jakarta – we are planning to invite academician, practitioners, operators and other experts from different countries to scrutinize these problems, and to offer sound solutions to the government of Indonesia.
I understand that you and your research and your experinces are very valuable to share with the road and transportation stakeholders in Indonesia. I hope that you consider travelling to Indonesia to share your experinces and expertise with us, and at the same time exploring the opportunity to work with relevant agencies to build road and transportation infrastructure in Indonesia.
The comittee of the symphosium is now working to look for sponsors to finance this international event, and I will get in touch with you soon. In the mean time you might give us information on the possible topic you might share with us. You may also recommend person you might think suitable to share with Indonesian stakeholders.
See you hopefully soon.
DR Marihot Siahaan, MA