By Fanis Grammenos

We usually renovate or replace systems when they no longer meet our requirements, the improvements often stemming from a new understanding of health, safety or efficiency concerns. We modify steep stairs to prevent falls, for example, or upgrade outdated electrical panels.
The same case can be made for remodelling roads. Sure, they have functioned for years—even if increased urbanization has called for traffic solutions in the form of speed bumps and four-way stops. But doesn’t it seem ironic that we paved bumpy, dirt roads to ease our trip and then, some half a century later, we purposely create bumps that make the ride unpleasant? Does a driver exist who actually likes speed bumps and humps?
Another relic from the past is the cross intersection. When people come to it, it’s a meeting place, but when cars reach it, it turns into a conflict zone. There are 32 ways that cars can collide in it. Unless the intersection is signed or signalized, every driver naturally believes in his right to act and move first. In fact, statistics show that four-way stop intersections have much higher frequency of collisions than their three-way alternative.
The lesson appears to have been learned: Neighbourhoods have started to replace their four-way junctions with other alternatives. One approach is to close one of the cross streets at the intersection, thus converting it into a three-way. Bollards, a clump of trees or planters, can make the closure an attractive feature.
Another effective solution involves the installation of a traffic circle in the exact centre of the intersection. From a driver’s perspective, this addition has the effect of turning the crossing point into four virtual three-way junctions; direct forward movement is not an option. As with the closure, the circle can host shrubs, flowers, or a tree improving the street ambiance.


A small circle provides a great safety bonus

Safety and Flow
Closures and traffic circles are just two of many ways of adapting the previous road network to the traffic it did not anticipate. When remodelling or designing neighbourhoods for traffic, two goals are uppermost: safety and flow, and in exactly that order.
What can traffic circles do for safety? Seattle’s traffic safety program, starting in the 90s, evaluated the impact of 119 traffic circles on accidents and injuries. It showed a whopping 90 per cent reduction in both. And when counting all costs related to accidents, the installation proved convincingly cost effective. Five hundred additional installations followed.
Vancouver did its own renovation and remodelling of certain streets. It included street closures, traffic circles, diverters, curb extensions, and extra traffic signs. A study looked at the before-and-after frequencies of collisions and injuries in the entire district. It found that there was a general reduction of accidents by 15 per cent and, within some neighbourhoods, of about 25 per cent.
But do traffic circles improve flow? Surprisingly, yes. Even though drivers slow down to negotiate the circle and other cars, the total network flow performance improves. The lesson: Neighbourhoods can do without the old four-way intersections and improve safety to boot. Traffic circles are smarter bumps that cars drive by, not over, recapturing the comfort of a smooth drive.
These renovations bring welcome improvements to an antiquated network system.
New neighbourhoods can use the lessons from these upgrades and provide a safe and well functioning network from the start. The techniques are easy to apply:
1. Avoid intersections entirely within a neighbourhood; unimaginable but possible.
2. When junctions are necessary, use the three-way version.
3. Use turns, not curves or bumps, to slow down cars.
4. On streets surrounding the neighbourhood, use traffic circles at the intersections
With these features in place, bumpy rides can once again be a thing of the past.

Reference: Seattle’s traffic safety program: www.usroads.com/journals/rmej/9801/rm980102.htm

Fanis Grammenos is a principal of Urban Pattern Associates and was a senior researcher at CMHC for 20 years. He can be reached at fanis.grammenos@gmail.com, and you can see his planning work at www.fusedgrid.ca