Cost effective alternatives for roads and parking lots
April 21, 2014 by ROSS MONSOUR
It has been a really rough winter for Canadian roads. Even the newly constructed surfaces that were funded as part of the government’s investment in infrastructure over the past few years are already scarred with a litany of potholes.
In a misguided attempt to complete as much work as possible with limited infrastructure dollars, municipalities used repaving techniques that are failing after only four or five years. During this period the ready mixed concrete industry has been touting the message of using concrete instead of flexible pavements as the best long-term, cost-effective solution in the marketplace.
The use of concrete as a paving material was prevalent years ago until the economics of being in political office dictated solutions that could be completed and justified in a city councilor’s four-year term. The cost of flexible pavements became the mainstay solution for municipalities. This strategy has left huge holes in Canadian infrastructure, physically and economically.
The economics of paving have shifted substantially for two main reasons. First, the cost of asphalt cement has risen due to material production shortages in the oil refinery business. And, second, asset management systems implemented by municipalities, mean lifecycle assessments now play a bigger role in materials and system selection.
This change in economics has made concrete paving more attractive on a first cost basis. As such, the concrete industry has developed several tools that allow municipalities to conduct economic assessments using their own material and construction costs. However, with any change in construction, many people are reluctant to implement new technology unless required to by administration.
In Ontario, the Ministry of Transport (MTO) has recognized and tendered many 400 series roads that have gone concrete in the last five years. The concrete industry convinced the MTO to remove the restriction on lower volume roads that would allow concrete as an alternate bid. This change was made almost two years ago, but there have still been no alternate bids for concrete from the MTO on the lower volume roads. This is mainly due to the reluctance of staff to deviate from their normal method of business, even if it could save the province money.
The Ready Mixed Concrete Association in Ontario (RMCAO) has continued to promote its perspective in spite of these challenges, and launched a new program that removes the barrier of the cost of design for alternate bids.
The Pavement Design Assistance Program (PDAP) was launched at the Concrete Canada show in December 2013. The intent of PDAP is to provide industry with the decision making tools to go to an alternate design for concrete paving while simultaneously pricing flexible pavements. PDAP provides an alternate concrete design, including CAD drawings that can be incorporated into the tender.
HOW DOES IT WORK?
Essentially you submit the details and costs of your project and engineering staff and the RMCAO produces the necessary documents for assessing whether an alternate bid will be in the municipalities interest to offer in the tender. PDAP is useful for determining the benefit of constructing a concrete parking lot versus flexible paving from an economic perspective. This program is accessible to any municipality, road engineer or building owner who may be looking for cost effective solutions and may be found at www.rethinkpavements.ca.
To date several projects have been submitted to RMCAO under the PDAP initiative. The following are three examples of the information and choice that have been forwarded on to the prospective clients:
REGION OF KITCHENER/WATERLOO—SPRAGUES ROAD (RR#75) RECONSTRUCTION
The road is rural between Brant County and the Region of Waterloo. The length is 1.1 kilometres long and is in need of a major reconstruction. It already had an existing base of concrete with an asphalt overlay as outlined in the engineering report commissioned by the Region. Materials costs used were supplied by the Region. The analysis looked at several possible solutions from both a flexible and rigid pavement solution including initial cost, lifecycle and contribution to greenhouse gas emissions. The sustainability aspect is determined using the Athena Impact Estimator of Highways, which includes global warming potential; fossil fuel consumption; and other criteria. Ultimately the most cost effective solution of both the rigid and the flexible pavements was an unbounded concrete overlay of 125 milimetres. The cost differential between either flexible design indicated a savings of almost $300,000 on an initial cost basis and another $100,000 on a 30-year life assessment for maintenance and repair for a total savings of $400,000 using a rigid option. The analysis in PDAP includes construction details, traffic staging and recommendations on the concrete materials specifications. This project is currently out to tender.
One municipality is concerned about the continual rutting of their intersections that make use of flexible pavements. The PDAP analysis looked at two scenarios for rigid and flexible pavements. One was for a reconstruction and the other was a new rebuild of the intersections. The complete analysis was done as in the previous case. The initial cost for rebuild of the intersection with either a rigid or a flexible pavement was similar. In another scenario where a total new intersection was to be built, the cost difference was a 20 per cent savings with a rigid pavement. The lifecycle costs when taking into account maintenance and repair resulted in a savings of 27 per cent versus the flexible option. This PDAP analysis has not yet been adopted by the region.
NELMAR DEVELOPMENTS—SARNIA PARKING LOT
The other unique aspect of PDAP is its ability to determine if a rigid pavement is more cost effective than a flexible pavement as a building parking lot. When the concrete industry started analyzing this type of construction, it quickly recognized an opportunity to promote it in this sector. The size of the parking lot can be substantially larger than the actual use of concrete in a building. This project has a parking site plan of 5,900 square metres of pavement. The PDAP analysis indicated a savings of almost $50,000 if a rigid pavement was used at a thickness of 125 millimetres. Other potential savings for rigid include the reduction in lighting due to the reflectivity of the paving surface.
The above three examples are just the tip of the iceberg where rigid pavements have a direct cost advantage over flexible. This is an argument that initially removed concrete as the choice for paving. Now that the trend has reversed and economic parameters indicate this situation will remain for many years to come, it’s time to start saving money on paving again.
This article was contributed by the RMCAO. Send comments to firstname.lastname@example.org