Ottawa drivers waiting to turn left at a busy intersection have probably wondered the same thing at some point: why does this light not have an advance green arrow yet? As it turns out, the answer involves a surprisingly long and data-heavy process that can stretch on for years before a single arrow gets installed.
What actually triggers a review
The city doesn't add advance left-turn signals on a whim, or even just because a councillor's office gets a flood of emails. According to city traffic staff, requests typically start with a resident complaint or a councillor inquiry about a specific intersection where left turns feel dangerous or backed-up. From there, city engineers open a formal review file and begin collecting data.
The data that matters
Three main factors go into the decision:
- Traffic counts — how many vehicles are turning left during peak hours, and how that volume interacts with oncoming traffic and pedestrians.
- Collision history — a documented pattern of left-turn-related crashes at the intersection carries significant weight, since preventing collisions is the primary justification for adding a signal phase.
- Resident and driver feedback — while testimony alone won't get an arrow installed, sustained complaints from the community help keep an intersection on staff's radar and can prompt an earlier review.
Engineers then have to weigh those factors against the intersection's overall signal timing. Adding a dedicated left-turn phase means less green time for other movements, so the change has to make sense for the whole intersection, not just the drivers turning left.
Why it takes so long
Given how many signalized intersections Ottawa has to monitor, and how each one needs multiple seasons of traffic count data plus a multi-year collision history before staff can justify a change, it's easy to see why some intersections wait years for an advance arrow — even when locals have been asking for one the whole time. Budget and construction scheduling add another layer, since physical signal upgrades (new signal heads, wiring, sometimes lane markings) often get bundled with other road work in the area rather than done as a standalone project.
The Ottawa angle
For Ottawa residents navigating everyday routes — whether it's the school run, a commute along a busy arterial like Merivale Road or Baseline, or just cutting across town during rush hour — these advance arrows can make a real difference to safety and travel time. It's one of those pieces of city infrastructure that most people never think about until they're the ones stuck idling through three light cycles trying to turn left. Understanding the process also explains why some intersections that seem like obvious candidates still don't have one: the file may simply still be sitting in the multi-year queue.
Residents who think a specific Ottawa intersection deserves a look can raise it with their city councillor's office, which can formally request a traffic engineering review.
Source: Ottawa Citizen
