August 5, 2021
The city of Vaughan, Ontario retained Englobe’s pavement engineering team to provide a viable solution to a serious problem: the pavement at an important fire and rescue station was failing… again. The asphalt pavement design which had been installed only two years prior had not only started to deteriorate in many areas, but was now deemed dire and required immediate, emergency action. The facility is an important hub for emergency responders who deliver critical life-saving services to the city and surrounding boroughs, and with an average response rate of 6 minutes, their ability to respond was being impacted by the failing pavement.
Resources were being wasted on ‘band-aid’ solutions; they did not know why the pavement was failing, and they did not have a long-term fix. They could not wait much longer to implement repairs.
Englobe to the rescue!
Pavement may not be glamorous, but these issues were impacting the unit’s efficiency, making it a high-priority and high-profile problem. The ruts, some 8 inches in certain spots, were collecting standing water, creating an unsafe environment for fire and rescue personnel. Many were concerned about the impact the deteriorated pavement was having on the vehicles, with the potential for adding unplanned maintenance costs. Most problematically, the state of the parking lot was so bad that it could be adding precious minutes to response times. The key client objective was a pavement design that would not fail under the heavy loads and constant wear-and-tear of a busy emergency services hub in both freezing winter and hot summer temperatures.
Englobe’s team set to work on recommendations for an immediate repair to the current pavement focused on getting the facility back on a safe and solid foundation. To do this, they dug to uncover the root cause for why the pavement was failing and to identify the best long-term solution. The team conducted subsurface investigations to determine the asphalt thickness and supporting granular base, local interviews to understand the day-to-day parking lot usage, and ran scenarios through advanced pavement technology to get a background and test design options.
Emergency response is a fast-paced, 24/7 operation utilizing specialized equipment including fire trucks which on average weigh some 35,000 pounds – far heavier than a normal vehicle load. The pavement requirements for this type of an operation needed to be custom to account for the heavy static loads of the trucks, how many times the trucks exited and entered the station, and the long-term impacts caused by the trucks’ sharp-turning movements.
A concrete solution
The Englobe pavement engineering team concluded that the pavement was predictably failing because the granular base was inadequate, the asphalt thickness was insufficient to accommodate the loads, and that an asphalt pavement design given the special circumstances was not ideal. They recommended concrete as an alternative, confident that concrete was the right solution because of its durability and longevity. They recommended replacing the complete parking lot with a 250mm thick concrete slab on grade, approximately 2500 m2, with a thickened edge. The design recommended excavation and removal of the existing asphalt parking lot, including the granular base to 1m depth, and installation of a new granular base, and a poured concrete pavement surface.
The design team advised removing the asphalt and pouring the concrete in stages to allow all emergency response units to remain operational with no disruption during construction. But custom staged construction added an element of complexity to the project, as optimizing pavement designs is not easy and phasing impacted thickening of the concrete. The pavement design also incorporated very intricate and detailed jointing plans to guard against cracking and other deformations that are common in parking lots. The jointing plan accommodated the many obstructions (manholes, sidewalks, etc.) and challenging parameters of the space (nothing was square) ensuring they did not impact the final product.
In the end, the concrete pavement was the perfect solution! The design minimized future liability, allowed construction to proceed without interruption to day-to-day operations, had long and short-term cost savings, aligned with aggressive project timelines, and was an environmentally friendly alternative to asphalt. Most importantly, it was a robust design built to withstand the wear-and-tear of fire and EMS traffic. The final product was a smooth parking lot built to facilitate and support fire, rescue and emergency services for city residents. It corrected elevation issues that had persisted since the facilities’ grand opening and had a significantly longer design life than the asphalt option.
Fire and rescue services are in the business of saving lives and anything that does not help to achieve this mandate, can be considered a hindrance.
Englobe played a key role in finding the best solution to ensure the station could offer a prompt response to all emergency calls.