Ensuring Affordable, Reliable, and Sustainable Local Government Services and Infrastructure with the Ministry of Highways Saskatchewan

A new prioritization system 

The province of Saskatchewan, like many across Canada, has quite a large number of culverts and other water channels running through it. Many of these are necessary for the functioning of the province because they carry water, and waste and are particularly useful when it comes to draining roads, but Alison M. Lara, the Asset Management Engineer of Operation Standards at the Ministry of Highways within the Government of Saskatchewan, says when it comes to maintaining them, we are basically being reactive instead of proactive. We didn’t have a formal, long-term strategy for culvert replacement. There are close to 27,000 through-grade culverts identified by the Ministry of Highways, and many of them are 40 or 50 years old, or more, whereas the lifespan for a typical culvert is only around 35 years. That is why we recently moved from a regionally prioritized system to a provincial prioritized system.

The notion that things needed to change began in 2014 when we started an inspection program to update our inventory and assess current culvert conditions. It took a while, but now we have inspected most of our network.” The only ones yet to be seen are in very remote areas or by hard-to-reach roads. In 2019, when most of the inspections were complete, we started working on our new process. The intention was to find a new way to maintain the culverts and address emergencies instead of being completely reactive. The way to be proactive was by developing a ranking system. We looked at the probability of failure, the consequence of that failure, and then the exposure level if it did occur. For each option, there were multiple factors to consider. For instance, in terms of the probability of failure, we looked at things like corrosion, seam separation and distress levels.” The consequences of failure it was more about the direct and indirect cost of the failure, like the bigger the failure, the costlier it is to replace. And for exposure, it was not about the culvert itself but about traffic volume on the road and the impact to the community.  

At the end, we developed a score for each and then added up the probability, the consequence and the exposure scores to get a total possible score of 561 points. In other words, the worse the condition, the higher the score, so we prioritized our program from the highest to the lowest scores. The province allocated a specific amount of money for this project, but there were some discussions about how to spend it. Rather than spending it all on the replacement work, we decided to assign 60% of our overall budget to the replacement category. This was then separated into three equal parts. Part 1 was for four different categories of high levels of service (LOS), part 2 was for our thin membrane surface network, which incorporates about 5,000km of our total network, and part 3 was for our gravel network, which is also quite comprehensive. Of the remainder, we put 35% to the corridor replacement, which includes resurfacing projects and clusters of culverts that perhaps have high priority scores so we can again get some economies of scale and do the replacements all at once. The final 5% was set aside for capital preservation work. We haven’t done this to date yet, but it’s in our pipeline.

This budget allocation has been important because, since 2019, it has ensured that we have successfully delivered our budget every year. The prioritization system means that we are able to justify completing a certain project over another based on the prioritization score, and it has meant that projects with greater need get addressed first. Overall, the goal is to replace a total of 2,000 culverts by 2030, but that is less of a target and more of the broad idea not really based on conditions. In terms of conditions, culverts are generally rated good, fair, poor or critical, with critical meaning they could cause a sinkhole in the road so they need to be addressed right away.

So far only one inspection of each culvert has taken place since 2014 and some were already in the fair to poor categories. Since deterioration is hard to predict or anticipate, an assumption was made – based on scientific methodology – that a certain percentage in each category moves to the lower category each year, in this case, 2%. This will be reviewed and refined as culverts are maintained and replaced, but it is a good standard to start with. So we decided that we wanted to focus on keeping our culverts in the good and fair condition categories and out of the poor and critical condition categories.

The next steps 

To achieve this, initial targets were set using mathematical formulations that can easily be refined, and the program of maintenance began, always starting with the highest score and going to the lowest. Unlike in the past, as works began, all the new replacements, their sizes and types were documented in our inventory so that we could make sure that our network was up-to-date with all the current information.  

If we don’t document what’s being replaced, our network is just going to continue to deteriorate. Eventually we want to look at developing new models, including some asset management software, so that we can actually get the software to select projects for us. This will involve the incorporation of our prioritization score, but it will be a more effective way to determine the deterioration of the network.

Alison M. Lara, Asset Management Engineer, Operation Standards, Ministry of Highways,  
Government of Saskatchewan