Tuesday, 30 June 2015

OR & Oxfam: optimising donation bank collections (write up and video now available) #ORblog

Many thanks to Tom Cherrett for a great presentation on his work with Oxfam illustrating the application of remote monitoring technology and optimisation techniques to collect donations more efficiently.

To view the full presentation please visit: http://www.theorsociety.com/Pages/Probono/latestnews.aspx

Below is a full write up from the event (by Nigel Cummings)

OR and Oxfam
(The OR Society: Joint Third Sector SIG, SORG and CORMSIS Event)

A recent presentation given by Tom Cherrett, Associate Professor, Logistics and Transport Planning, Southampton University, illustrated the application of remote monitoring technology and optimisation techniques to collect donations more efficiently.

Many shops around the country have “food banks” where shoppers can deposit unwanted non-perishable items possibly bought in a BOGOF deal. Charity shops also often receive items that they cannot sell but are perhaps too good to throw away. Oxfam recognised that collecting these items accounts for something like 20% of their income and thought O.R. might be able to make significant reductions in this.
While the main focus of Tom’s presentation concerned work done for Oxfam, he also had the time to detail some of the processes involved in achieving logistics efficiencies in other organisations.  Primarily his talk concerned the implementation of remote sensor technology in donation banks to help organisations like Oxfam more efficiently judge “fill levels” and allocate appropriate times for donation bank collections.

Using the fill levels reported daily and derived collection strategies using tabu search methods Tom Cherrett’s team had achieved considerable efficiencies and overcome many obstacles associated with donation bank management. One of the problems they had to address was neatly illustrated by a slide which showed a small child being used by donation thieves to enter donation banks and remove contents (Fagin would have been proud!).
Such despicable acts were all too common, and it was a goal of this research to find ways of reducing this type of pilfering.  The work undertaken had involved equipping Oxfam banks with infra-red sensors that measured how full the banks were, reporting the data twice daily, and using it to schedule collections more efficiently whilst reducing thieving.
O.R. methods were employed to help provide indicators as to the most appropriate times to make collections. The proposed routes output by the algorithm used for each day of operation were then adjusted by Oxfam's transport manager to take into account issues such as round balancing, vehicle access restrictions, staff availability and other constraints.
A trial was run 2013 with the results showing a relatively modest time and distance savings (~3%) initially, these being limited by Oxfam's fixed shop servicing constraints. It was estimated that savings of up to 25% could be made by easing these restrictions. These savings were based on a set of rules that only allowed banks to become eligible for servicing once they had reached a specific fill level.
The fill/collection problem was made more complex by the need for the collection vans to visit Oxfam shops on a fixed schedule basis to remove unsold textiles too. Following live and simulated trials, the results suggested that time and distance savings of up to 30% over the current fixed schedules could be achieved when a minimum bank and shop fill level of between 50% and 60% was used as a collection trigger.
Some of the outcomes from the project are now being developed commercially in the form of a mobile phone app, to allow area managers, shop managers and drivers to communicate and manage collection scheduling in a more dynamic way. Other benefits included greater flexibility for transport managers working at Oxfam, to schedule ad hoc work and offer shops additional collections. The Oxfam drivers benefited too as the efficiencies achieved in logistics and better division of labour meant that sometimes it was possible to finish work an hour early.
The work with Oxfam is ongoing, and it is expected that further efficiencies will be achieved.