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Foodie traffic fixes

by Laura Howes
January 17, 2020 | A version of this story appeared in Volume 98, Issue 3


A German gherkin experiment

A truck sprays brine on the autobahn.
Credit: Bayerische Staatsbauverwaltung
In a pickle: Spraying brine on the autobahn

When winter comes, streets crunch underfoot with salt and grit, laid down to lower the freezing point of water. But while most road salt is mined especially for that purpose, the German state of Bavaria has found an unusual source for some of its salt: Gurkenwasser, the brine from pickling gherkins.

The Bavarian transport ministry is responsible for treating a total of 23,000 km of autobahns and streets. This creates a bit of a pickle—treating the streets in winter uses a lot of salt, which has both an economic and an environmental cost. Excess salt may run off into groundwater and surface water, so the ministry uses blends of brine and granular salt to reduce waste. At warmer temperatures, wet mixes help the salt stick to where it’s needed. This year, a pilot project will source some of that brine from a local company that makes pickles.

Develey Senf & Feinkost’s pickle plant in Dingolfing, Germany, has 1,000 silos, each filled with about 10 m3 of brine to store cucumbers during the pickling process. This pickling produces the crunchy, tangy gherkins that go so well with pretzels and beer.

To make the brine road ready, Develey plant manager Thomas Huber says workers filter out all the pickle particulates and concentrate the solution from 9% to 21% salt by weight. Recycling the brine and reducing the amount of salt that goes into the environment are, according to Bavarian transport minister Hans Reichhart, “eine Win-Win Situation!” The transport ministry estimates that using pickle juice this winter could save 700 metric tons of salt.

Newscripts recalls in 2007, when sweet-toothed sheep were seen licking streets in Wales after the local authorities switched to a sugar-based grit. Hopefully the pickle brine won’t attract similar behavior.


Grocery store traffic

A grocery cart filled with healthy food.
Credit: Shutterstock
Quick trips: Can math speed up grocery shopping?

For humans searching their local supermarkets for pickles or other goodies, navigating both stores and fellow shoppers can be infuriating. That’s certainly the Newscripts gang’s feeling when visiting the UK and trying to quickly pick up British snacks to take back home. So it seems reassuring that mathematicians at the University of Oxford and the University of California, Los Angeles, have used shopping data from UK supermarket chain Tesco to suggest how to make grocery shopping more efficient (Phys. Rev. E 2019, DOI: 10.1103/PhysRevE.100.062304).

Congestion, the authors point out, doesn’t just annoy shoppers but also slows down staff fullfilling online orders. The mathematicians’ models show that if, for example, people who buy pasta also often buy cheese, stores should be arranged to reduce the distance between those ingredients. Arranging popular items around the perimeter of the store, like a ring road of high-volume goods, also reduces shopping-cart traffic jams.

Although it’s unclear if grouping Marmite, crumpets, and tea bags for British expats has enough payoff to influence store layout, the authors suggest that their approach can also help the design of museums, restaurant buffets, and even poster sessions at conferences.

Laura Howes wrote this week’s column. Please send comments and suggestions to


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