Things That Work: Traffic Posts

You don’t often hear news about the crashes that didn’t happen. Today we’d like to highlight something already making real-world safety impacts in Sacramento: traffic posts (aka. delineators) on 15th & 16th Streets in Downtown.

These traffic posts reduce the speed of cars (and severity of injuries) as well as channelize traffic – stopping cars from changing lanes at the crosswalk and potentially striking pedestrians who have started crossing. 

Speed kills, and these multi-lane arterials are exactly the type of streets on the High Injury Network the city needs to address in a data-driven approach to Vision Zero. In the eight years before the traffic posts were installed, 24 people were severely injured and two people were killed along the 15th & 16th Street corridor.

During our speed survey at R & 16th, cars were measured moving through the traffic posts at an average of 24 mph, compared to cars a block closer to the freeway averaging 33 mph.¹ This difference in speed halves the likelihood of severe injury or fatality for people walking from 50% to 25%.²

These traffic posts (or quick-build curb extensions & pedestrian refuge islands) do not solve many of the issues of dangerous street design.³ However, they are a much-appreciated start within a limited budget while the city identifies additional funding and implements more concrete solutions. We should be constantly asking ourselves what the next smallest step is to make Sacramento streets safe, and to go do that thing now. Traffic posts are that small step.

Thanks to Megan Johnson and Sacramento Public Works for the improvements (including the maintenance crew for the tireless replacement work), we hope to see more innovative projects like them across the city.

Footnotes

1. It’s impossible to isolate a single variable in an urban environment or attribute the decrease entirely to the delineators; however, other variables including pedestrian presence, vehicular platooning, and light cycling were controlled for to the extent feasible. N>37
2. Tefft (2013)
3. e.g. the author was nearly run over in the 16th St crosswalk getting to this survey and yield rates at R street are still not great