Abstract Manager

Jurisdictions across Canada are looking at increasing the posted speeds on freeways to 120 km/h, and the Ontario Ministry of Transportation (MTO) investigated the potential for posted speeds of 120 km/h, with a corresponding design speed of 140 km/h allowing for increased travel time savings for people and goods, which has the potential for strengthening the Ontario and Canadian economies.

As the TAC GDG only provides design guidance up to 130 km/h design speeds, MTO initiated a research assignment to develop and recommend design parameters for a 140 km/h design speed for freeways. The objective was to inform MTO’s future update of the MTO Design Supplement to the TAC GDG and the MTO Roadside Design Manual. A key challenge for this study was identifying data from other jurisdictions that have established design standards for a 140 km/h design speed.

Our project team engaged subject matter experts (engineers, human factors professionals, safety professionals, and a research institute) from across North America to conduct the research and prepare the recommendations. The report outlined the recommended 140 km/h design speed values for 31 select design parameters; the methodology used to determine the recommended design parameter values; the associated research informing the decision-making process; and the rationale to determine these values.

The key objective of this presentation is to provide an overview of the methodology used to determine the recommended values of the 31 highway design parameters developed and discuss the findings of select design parameters (sight distances, expected operating speeds, lateral friction, maximum grades, cross-slope, and barrier flare rates).

The presentation will review the process followed, which centred around a workshop with MTO staff and the subject matter experts with the goal of reaching consensus for the recommended values of each design parameter. We will present key aspects of the pre-workshop phase (literature review; information gathering; jurisdictional review; and rationale for determining values for the design parameters), workshop, and post-workshop phase (additional research, presentation to MTO Senior Management, identifying implementation risks).

There will also be a discussion on the limitations to the study, recommendations for further research such as additional levels of MASH testing for roadside barriers and updated lateral friction testing for new tire/pavement combinations.

Attendees will gain insight into the process used to determine the design standards recommendations; risks associated with implementing the values and understand the process of adapting or developing new highway design guidelines.