Potholes

Thank you to the Winnipeg Free Press for covering this important issue. See a recent article: City can’t get its fill of potholes

This more technical update was provided from the Manager of Street Maintenance. Please know this update is for ‘this year’ and we are looking into longer term solutions as I fully expect conditions will be similar next year.

During the spring, we had 7 crews focusing on Priority 1 streets and hazardous potholes on Priority 2s and 3s. Currently, we aim to have 12 crews (based on labour and equipment availability) working 5 x 8-hour shifts. Overtime is offered to extend regular weekday shifts to 10 hours, and additional weekend shifts are scheduled when hot asphalt is available. P1 potholes are reported by Regional Inspectors and through 311, and are prioritized accordingly. Once P1s are under control, some crews will shift to address P2 potholes. P3 and back lane potholes are reported by Zone Foremen and through 311. Crews are then directed to address all potholes within the block of each service request.

 Issues:

  • Some P3 potholes do not get addressed within the season due to the limited number of crews versus the increasing workload.
  • We face challenges with the availability of external roller rentals. Rollers provide the best compaction for lasting repairs. It would be beneficial to own some rollers to ensure we are adequately equipped.
  • We’ve shifted labour from concrete crews to asphalt crews, to keep the 12 crews going with adequate labour. We do not have access to additional equipment (asphalt transporters and rollers) to establish additional crews.

We have recorded a significant increase in pothole repairs from January 1st to July 1st, 2024, compared to the same period in 2023. The number of potholes filled has surged from 98,795 in 2023 to 179,721 in 2024. This uptick in repairs can be attributed primarily to an increase in the amount of rainfall and the number of rainy days, which have created challenging conditions for road repairs.

 Key Statistics:

Year: 2023

    • Potholes Filled: 98,795
    • Rainfall (mm): 73
    • Rain Days (>=1mm): 13
  • Year: 2024
    • Potholes Filled: 179,721
    • Rainfall (mm): 297
    • Rain Days (>=1mm): 29

Technical Explanation:

Potholes are a common road defect caused by the infiltration of water into the pavement structure, which weakens the underlying base and sub-base layers. The freeze-thaw cycles typical of Winnipeg’s climate exacerbate this problem, leading to the formation of potholes when water freezes, expands, and thaws.

In 2024, Winnipeg experienced a substantial increase in both total rainfall and the number of days with significant rainfall (>=1mm). The data indicates 297 mm of rainfall over 29 days in 2024, compared to 73 mm over 13 days in 2023.

This dramatic rise in rainfall has resulted in the following challenges:

  • Increased Water Infiltration: Higher rainfall amounts lead to more water seeping into the pavement, weakening the road structure and increasing the likelihood of pothole formation.
  • Frequent Repair Interruption: With more rainy days, the window for conducting effective repairs is reduced. Rain delays repair work and can cause newly filled potholes to fail if the material does not set properly.
  • Impact on Repair Materials: Rain affects the performance of repair materials. During the winter and early spring months, the Public Works Department relies on cold mix asphalt for temporary pothole repairs. Cold mix asphalt is more pliable and easier to apply in colder temperatures, but it is less durable and more susceptible to moisture.

This year, many of the cold mix repairs failed sooner than in previous years due to the increased rainfall. The constant exposure to water prevents the cold mix from properly bonding with the existing pavement, leading to quicker degradation and the need for repeated interventions. Once hot asphalt becomes available, typically in late spring and summer, it is used for more permanent repairs. Hot asphalt provides a stronger, more durable bond and is less affected by moisture. However, even hot asphalt can face challenges in rainy conditions. Prolonged exposure to water can hinder the curing process, leading to compromised repairs. The reliance on cold mix asphalt in the earlier part of the year means that early repairs are more vulnerable to failure, especially in the wetter conditions experienced this year.

 Charts and Summary Table:

Year Operations Customer Service Environmental April 15th-July1st % Labour Hours
Potholes Filled Total SRs Total Precipitation # of rainy days (>=1mm) Weekday Weekend Regular Overtime
2018 81,822 3,757 149.6 13 98% 2% 98% 2%
2019 82,724 3,498 73 14 100% 0% 99% 1%
2020 77,473 2,862 123.6 18 97% 3% 97% 3%
2021 56,983 2,031 95.2 9 96% 4% 97% 3%
2022 134,828 8,210 353.2 26 90% 10% 75% 25%
2023 98,795 5,312 73.3 13 87% 13% 84% 16%