• Opinion
  • December 21, 2018
  • 6 minutes
  • 2

How we’re using behavioural science to decrease litter in Philadelphia

Opinion: We ran two different policy experiments that will inform future policy

This piece was written by Nandi O’Connor, Policy & Digital Content Manager for GovLabPHL. For more like this, see our cities newsfeed.


Tackling litter is a persisting challenge for many cities and Philadelphia is no exception. With nearly 1.5 million tons of waste disposed by residents and businesses each year, and only 40% of it being recycled, there’s still a lot of work to be done in order for the City to advance it’s sustainability goals.

Recognising this as a challenge that needed a committed group of people to think through, implement solutions, craft policy and monitor outcomes, the City launched the Zero Waste and Litter Cabinet in 2017.

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Over the past two years, the cabinet has committed its efforts to reducing waste entering landfills or commercial incinerators, combating litter and enhancing the cleanliness of streets and public spaces.

Within this cabinet, a behavioural science subcommittee sits amongst four others with the goal of using the experimental outcomes to inform policy changes. The creation of this particular subcommittee was inspired by GovLabPHL, a cross-agency team stationed in the Mayor’s Office that promotes and supports the use of evidence and data in government policymaking.

The behavioural science subcommittee has been able to complete two experiments — thanks to GovLabPHL team members and academic partners at the University of Pennsylvania, Swarthmore College and Temple University.

One experiment was to decrease litter through the manipulation of trash receptacles and another was to increase recycling rates through the distribution of recycling bins with lids. As a result of both efforts, the City was able to better understand residents’ waste behaviours. Having these insights to guide how limited funds can be smartly resourced is invaluable.

Distributing bins with lids

While standard recycling bins are readily available for residents at designated locations throughout the City, recycling bins with lids were distributed to neighbourhoods within two separate recycling routes for the purpose of this experiment.

The City was interested in learning if lidded bins increase the amount of recycling tonnage collected and reduce litter, and by how much.

The two recycling groups selected for this study were located in the Port Richmond and Brewerytown neighbourhoods, chosen based on where the City’s new Litter Index (a metric for measuring litter) was being piloted.

With the help of volunteers, 2,400 newly lidded recycling bins were distributed at recreation centres in these communities with the intention of influencing recycling volume, examining recycling tonnage from residents and measuring litter along four selected routes.

Sanitation workers collecting along these routes were asked to complete surveys recording resident recycling bin lid usage. The City’s litter index was used to measure the effect of the new bins on litter rates.

Existing data collection procedures are not always created for the purposes of evaluation

The results of this experiment varied by neighbourhood. Port Richmond saw an increase  in recycling volume as a result of the recycling bin distribution. If this intervention were to be implemented across all of Port Richmond, we estimate an annual savings of $9,884.16 in that neighbourhood!

In Brewerytown, the results were inconclusive due to significant variation in tonnage data between the two recycling routes.

We learned that existing data collection procedures are not always created for the purposes of evaluation, and the results have inspired us to improve data collection procedures for future experiments.

Altering trash bin placement

Another project launched by the Zero Waste and Litter Cabinet’s behavioural science subcommittee in 2017 took a look at how altering the number of available trash receptacles can influence litter and illegal or short dumping behaviours.

The experiment studied whether increasing or decreasing the amount of receptacles decreased litter and staff hours picking up litter for the area. Four parks and four commercial corridors in the city received a manipulation that either increased or decreased their number of trash receptacles by 75%. Two non-treatment periods returned the number of receptacles to the original amount.

The results varied by treatment site but overall we found that increasing the number of trash receptacles led to a decrease in time spent by staff picking up litter by 30 minutes a day. Results also confirmed that less trash receptacles increased the amount of litter.

 The Zero Waste and Litter Cabinet will use the results from both experiments to better inform how the City utilises financial and operational resources moving forward. Insights will be used to advise policymaking as well as next steps towards the City’s zero waste goals.— Nandi O’Connor

The full report detailing each experiment is linked in the references below. 

(Picture credit: Unsplash)

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