“Worst first” is a common practice in road maintenance for many municipalities — the roads that are in the worst repair, or that are generating the most complaint calls from ratepayers, are the first to be repaired or resurfaced.
In Ontario, some of this practice began in the pre-1995 era, when municipalities received up to 50 percent funding from the provincial government for road rehabilitation, with funding given to repair only the worst roads.
With the elimination of provincial funding in 1995, many municipalities struggled to close the funding gap. In the Town of Markham just north of Toronto, as in much of the Greater Toronto Area, this problem was compounded by the fact that the roads built during the housing boom of the 1970s were nearing their 25th anniversary. The backlog of road repairs had grown.
The story of how Markham overcame its backlog and planned for its future, and did it in a way that meets sustainability priorities, contains lessons that apply not just to paving but to many of the challenges municipalities face today. Markham decided to break the old cycle of dealing with the worst roads first and move to a proactive sustainable preservation strategy.
Beyond “worst first”
Markham’s backlog of road repairs totaled about 60 kilometres by 2000. In 2001, the municipality decided to first deal with the backlog, and when that was done it would then be feasible to move beyond the “worst first” approach to a more sustainable approach.
Accordingly, Markham adopted a five-year plan to rehabilitate 117 km of its 955 km inventory of roads, partly to clear the backlog, but also to address additional road needs during that period.
Part of the answer was financial — doubling the investment in roads from $2 million per year to $4 million, and indexing that level of funding over the years.
The other part of the answer was the development of a continuous improvement program with the objective of sustainability, focusing key drivers defined as:
• Community: maintain a high ratio of roads rated as Good or Better;
• Economic: find ways to reduce the overall lifecycle cost; and,
• Environmental: reduce the environmental impacts of the rehabilitation work.
Moving from a reactive to a proactive strategy involved finding new ways of working. This included training staff to inventory roads in a new way. Rather than looking for potholes that needed to be fixed, Markham’s road crews were trained to recognize early-stage problems such as cracks that might turn into potholes without intervention.
Visual inspection was backed by a testing program that helped find problems before they became serious. This meant buying more testing equipment and training staff in its use. As well, new equipment was purchased to seal cracks and other elements of the sustainable, proactive maintenance approach.
Expanded asphalt stabilization
As Markham adopted several techniques to “reseal” the surface of new and rehabilitated roads early in their lifecycle — to extend longevity and “ride-ability” — the town discovered that many roads were structurally unable to handle increasing traffic loads and volumes. The conventional approach to increase the strength of the road base would involve full excavation; this would be expensive and disruptive, and would generate a large volume of waste aggregate and asphalt.
Markham sought a better solution to meet its sustainability objectives.
Working with its asphalt contractor, the town adapted a recycling technique called Full Depth Reclamation with Expanded Asphalt Stabilization (EAS). This technique is widely used on rural highways and roads but needed to be adapted for urban roads with curbs and gutters. EAS involves a machine driven along the distressed pavement that uses a milling drum to rip up the pavement along with some of the granular material below it; the mixture is then injected with foamed asphalt and compacted in place. The new pavement layer is at least 20 percent stronger and will last 20 percent longer than the one it replaced. The in-place recycling method requires no additional aggregate and with the cold-foamed asphalt, also reduces energy needs and emissions.
EAS still requires a top layer of hot mix asphalt and Markham found a sustainable solution for that as well. The town partnered with the Miller Group and the University of Waterloo on an Ontario Centres of Excellence grant to use old tear-off shingles as an additive to the asphalt mix, to reduce the volume of virgin aggregate and improve the quality of the final product. In 2007 and 2008, 135 tonnes of used shingles were diverted from landfill and applied to Markham roads; these roads are performing admirably.
Although Markham needed to adapt EAS to its urban setting through some innovative approaches, it has found situations where pavement-recycling techniques such as EAS may be impractical or too difficult to be effective. In the case of intersections and cul-de-sacs, roundabouts, narrow laneways and along streets with low tree canopies, Markham often needs to use more conventional techniques that do not involve recycling.
Markham is pleased with the results to date. Staff compared EAS pavement performance with roads rehabilitated with conventional “shave-and-pave” (S&P) approaches (shaving off a layer of asphalt and resurfacing the road with hot mix asphalt). While the information is preliminary and the sample size is small, comparisons of roads rehabilitated using the two techniques in 2002, 2003 and 2004 found that the roads done with EAS consistently out-performed the S&P roads and will make an excellent base for preservation techniques.
The cost of EAS is comparable to S&P when the longer lifespan is taken into account. With EAS combined with the preservation program, Markham expects to reduce pavement costs by $25 million over the next 25 years.
The big picture is also encouraging. In 2004, 86 percent of Markham’s roads were rated as Good or Better; in 2008 it was 89 percent. While the provincial average has been trending downwards since 2004 to 70 percent in 2008, Markham’s roads are among the best in Ontario.
Peter Loukes, P.Eng., is Director, Operations in the Community & Fire Services Commission for the Town of Markham. Contact Peter at email@example.com