Here's how bad Montreal's asphalt gets in just 5 years

It's no secret that many of Montreal's streets are in a dire state of disrepair, but now residents can see just how bad they are and how quickly they've deteriorated.

The City of Montreal began releasing data this year on the condition of nearly every street, block by block — part of Montreal's "smart city" initiative, which calls on residents to find solutions to urban problems.

A CBC analysis of that data reveals how quickly the degradation can happen: roads that were freshly paved in 2010 had deep fissures and tar patches by 2015, with small cracks branching out in all directions.

The map below lets you compare the state of the pavement in 2010 (left map) to 2015. You can slide the vertical bar in the middle to see the changes. The key in the top right shows the colour-coded rating that the city assigns to each street, from from "excellent" to "very bad."

Demerged municipalities including Westmount, Hampstead and the West Island suburbs are not included.

Half of Montreal's streets are rated 'bad' or 'very bad'

The data is collected by special trucks fitted with sensors that detect cracks and potholes.

Each block of pavement is assigned a number based on the Pavement Condition Index (PCI), a standard in use in many cities in Canada and the U.S.: one is terrible, 100 is pristine.

Those numbers are then grouped into grades, from "very bad" to "excellent."

In the five-year period between 2010 and 2015, the number of Montreal blocks with a positive rating decreased, while those with a "bad" or "very bad" rating grew from a third of all blocks in 2010 to nearly half of all the blocks scanned by 2015. 

Normally, a street loses about five points in the PCI scale each year, according to Jean Carrier, Montreal's chief of asset management. If no maintenance is done over five years, a stretch of pavement can slip from good condition to average.

"Five years is a long time," Carrier said. "If we don't do any work on it, degradation will happen."

And for the most part, Montreal's streets degraded at that rate. Of the road segments that decreased in quality in those five years, the average PCI loss was 20 points.

What 5 years of deterioration looks like

But some road segments lost far more than five points a year on the scale. Below are Google screen grabs of Montreal blocks that saw large drops in quality.

Note: This stretch of Alexis-Nihon Boulevard has been repaved since 2015.

More money for roads

"Certain street segments are indeed in a bad state, but since 2014, the City of Montreal has made unprecedented investments in the road network, water mains and sewers," said Marie-Ève Courchesne, spokesperson for the city.

Carrier concurs.

"Back in 2010-2012, there was less roadwork being done than [there is] today," he said. "2015-16 was a good year for roadwork. We'll see how much we improved in the next evaluation cycle."

The estimated budget for roads in 2017 is $218 million, almost five times the amount devoted in 2010.

There have been other changes, as well: Back in 2010, the Charbonneau commission into collusion in the construction industry had not yet revealed that the asphalt quality used in paving jobs was often substandard.

Since then, there have been changes in the tendering process and in the supervision of roadwork.

Montreal is planning on scanning the road network regularly, but it's a lot of work to cover 4,000 kilometres of city streets. In one year, only half the arterial roads and one-quarter of residential streets can be done. So a full picture of the city is only possible every four years.

Still the city will publish data every year. The next release is expected in 2018.

Pierrefonds and Saint-Laurent stand out

The data shows that some of the best-kept streets are in the boroughs of Pierrefonds-Roxboro and Saint-Laurent. They have the highest proportion of street segments with "excellent" and "good" ratings.

There are historical reasons for this going back before the municipal mergers, Carrier said. When these boroughs were still cities, they used a different paving technique with a flexible foundation made of granular material, which made it more resistant to wear. These boroughs still use this paving technique today.

Pre-merger Montreal, other hand, used a flat concrete base that absorbed less shock and cracked easier, Carrier noted. 

A city spokesperson later added that these flat foundations were mostly built in the 1960s.

"We are slowly converting the city's streets to the flexible asphalt," Carrier said.

Anjou, LaSalle, Rosemont at the bottom

On the other end of the spectrum, some boroughs stand out as having more terrible streets than others. Anjou, LaSalle and Rosemont–La Petite-Patrie lead the city with the highest proportion of segments in "very bad" condition in 2015.

According to the city, boroughs are responsible for paving residential streets, while the central administration handles arterial roads.

Percentage of road segments in 'very bad' condition in 2015

Anjou 29%
LaSalle 27%
Rosemont–La Petite-Patrie 26%
Mercier–Hochelaga–Maisonneuve 25%
Côte-des-Neiges–Notre-Dame-de-Grâce 23%
Ahuntsic-Cartierville 23%
Lachine 23%
Villeray–Saint-Michel–Parc-Extension 22%
Montreal North 22%
Southwest 19%
Ville-Marie 18%
Verdun 18%
L'Île-Bizard–Sainte-Geneviève 17%
Plateau-Mont-Royal 17%
Outremont 16%
Rivière-des-Prairies–Pointe-aux-Trembles 14%
Saint-Leonard 13%
Pierrefonds–Roxboro 11%
Saint-Laurent 11%