The streets of Mendoza

by Tarah Hodgkinson

In previous blogs, we have spoken about tree canopy and its correlation with reductions in not only heat, but also crime. Indeed, 3rd Generation CPTED now includes environmental sustainability as a central strategy for safer places. I recently experienced this firsthand during travel to South America.

One of the wonderful things about travel is the opportunity to see beyond your view of the world to another way of doing things. I was reminded of this during a recent trip to Mendoza. 

Mendoza is a city in Argentina home to one of the best wine regions in South America. Beyond the wine, the city itself is really interesting. Situated in the desert, Mendoza is subject to the extreme desert heat. To combat this, the streets are lined with trees. 

Indeed, the streets of Mendoza feel welcoming and engaging. You can instantly feel the difference in heat when you leave the treelined streets and enter one of the city’s many parks. 

This commitment to tree cover exists in the cities and also along the routes to the original olive farms and vineyards. This was done to protect the agricultural produce during transport so it wouldn’t spoil. It also protected the drivers. 

However, it wasn’t the tree canopy that really caught my attention, rather it was the infrastructure that supported the trees. Throughout the city, deep canals collect and supply water to the trees. These “acequias” were originally designed by the indigenous peoples of what is now known as Mendoza. Despite the destruction of much of the Indigenous peoples and culture by colonizers in the 16th century, the canal system remained. 

However, while the canals are imperative to supporting the survival of these trees, and contribute to the liveability of the city, they also pose a huge physical risk. This is because the canal system is wide open. 

PHYSICAL SAFETY

In speaking with local residents about the canals, many told us stories about people walking home at night, missing a step, falling in, and getting hurt. They shared that this was often tourists, or people unfamiliar with the area, but after a few beers, the locals were just as susceptible.  But this risk seemed to be an accepted one, in order to maintain the trees. 

As someone trained to see the city in a particular way, I couldn’t believe that these canals weren’t covered with grates or something else that might protect people from falling in and getting hurt. Coming from North America, where liability is everything, it was interesting to be thrust back into another culture that prioritizes other values. 

It also reminded me that our western view isn’t necessarily the right one. For example, an extensive grate system is quite expensive and may not be achievable. Or perhaps they have agreed to trade one form of safety (physical), for another (heat exhaustion), with the acknowledgment that you can just look where you are going. Either way, the result is absolutely beautiful – albeit a little tricky to navigate. 

So, if you are heading to Mendoza, watch your step! 

Trees and crime?

Tree canopy in the island city of Montreal

What to do about trees? You know, the CO2-sucking kind. Do they influence crime opportunity? I doubt they cause or solve it. Do they matter at all? I've written about the crime and tree theory before. 

New research calls for a revisit.

Yesterday my Safe Cascadia colleague Tod Schneider found the latest evidence. It was a study called "The relationship between tree canopy and crime rates across and urban-rural gradient in the greater Baltimore region".

First, what does CPTED have to say? 

CPTED guidelines generally mention trees only in passing. A typical example is the Tempe, Arizona CPTED guidelines on the Florida DOCA website. Those guidelines, as others like them, practically ignore canopy. They do suggest pruning for better sight lines and street lighting. But mostly trees are invisible in guidelines, unlike in the real world where they are not. 

When urban planner Elisabeth Miller and I wrote Saskatoon's CPTED guidelines we spent a bit more time on trees. We drew on research showing the positive effects of trees, particularly a recent Portland, Oregon study.

Our conclusion: "Tall trees, especially those older trees with large trunks, are often associated with beauty and should be retained." 

And what does this latest research say? In the June issue of the journal Landscape and Urban Planning, US Forest Service researchers concluded "a 10% increase in tree canopy was associated with a roughly 12% decrease in crime." 

Canopy along Moscow street

It's not the definitive word, of course. Yet their tree/crime relationship held statistically for public and private areas. It also held for different socioeconomic neighborhoods. It didn't matter if low crime rich areas had more tree canopies and poorer areas didn't. They controlled for other factors like public versus private land. Same result.

One exception - a patch of industrial, abandoned areas where canopies made things worse. Yet they were the exception not the rule. Mostly the study results suggest tree canopies contribute to safety. 

What to do about trees? Plant, prune and leave them alone.