Horizontal Curve Assessments
Many curve safety problems can be fixed with signs and delineation rather than reconstruction. We assess each curve in the field to the Ontario Traffic Manual and the TAC Geometric Design Guide for Canadian Roads: a ball bank study to set the advisory speed, measured sight distance through the curve, and a review of warning signs, delineation, and the roadside beyond the curve.
Serving municipalities across Ontario from St. Catharines.
What we deliver
- Ball bank study in both directions to determine the recommended advisory speed
- Measured stopping sight distance through the curve, compared with TAC requirements
- Review of advance curve warning signs and advisory speed tabs to OTM Book 6
- Chevron alignment signs, pavement markings, and lighting review
- Roadside hazard rating outside the curve, with a guide rail assessment where warranted
- A summary of recommended actions for each curve, with inspection photographs
When to assess a curve
- A history of run-off-road collisions or resident complaints
- No advisory speed is posted, or the posted one has never been verified
- Before resurfacing, when signs and markings can be corrected at low cost
- As part of a network-wide road safety review
What we check in the field
- Curve geometry, posted speed, and traffic volume
- The advisory speed, measured with a ball bank indicator
- Whether drivers can see far enough through the curve to stop
- Advance warning signs, advisory speed tabs, and chevrons
- Edge lines, centrelines, and lighting
- Embankments, fixed objects, and water outside the curve
Standards and references
- Ontario Traffic Manual Book 6, Warning Signs
- TAC Geometric Design Guide for Canadian Roads
- MTO Roadside Design Manual
Common questions
- How is the advisory speed for a curve determined?
- With a ball bank study. We drive the curve in both directions at gradually increasing speeds with a ball bank indicator mounted in the vehicle, and set the advisory speed at the highest speed that stays within the limit in the Ontario Traffic Manual.
- When is an advisory speed tab required?
- Under OTM Book 6, an advisory speed tab is used where the recommended advisory speed is 10 km/h or more below the posted speed limit.
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Haldimand County Roadside Safety Review
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Town of Fort Erie · 2026
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