We like to think of our homes and neighborhoods as safe havens, but the streets just outside can be dangerous: almost a quarter of car accidents occur within one mile of the driver’s home.
Complacency, distracted and reckless behavior, weather conditions, compromised visibility, and traffic congestion all contribute to accidents — but the biggest factor is speed.
The faster a vehicle goes, the less likely it is to be able to stop or avoid the accident. When an accident occurs, the greater the speed, the greater the impact.
Slowing down is the simplest and most effective way to make our streets safer. Collisions and fatalities can be significantly reduced with only minor decreases in vehicle speeds.
So, how do we get drivers to slow down?
Municipalities use a technique called traffic calming, where the roadway is designed to make the most convenient way to drive also the safest. The strategy encourages more responsible, attentive driving.
Traffic calming works because drivers — consciously or sub-consciously — are taking in and responding to environmental factors as they drive. Traffic calming measures will change the way drivers behave.
There are many traffic calming techniques to choose from:
- Speed zones
- Vertical deflections
- Horizontal deflections
- Signage and road markings
- Physical barriers
- Non-vehicle spaces
Each of these categories includes several different measures that can reduce vehicle speed.
Traffic Calming Methods
Posted speed limits are the most basic way that municipalities can limit drivers. These can take the form of zoning regulations near vulnerable areas or at certain times, such as reduced speeds near schools and parks during daylight hours.
Speed limits are relatively easy and inexpensive to implement. Unfortunately, without police enforcement, they are also easy to ignore. The enforcement requirement makes speed limits expensive to execute in the long term.
Speed limits are often used in conjunction with other traffic calming methods to encourage compliance without routine legal enforcement.
Vertical deflections are built, raised obstacles that visually and physically encourage vehicles to reduce their speed to pass. They can take many different forms:
- Speed bumps
Raised elements about 3 inches high and 3 feet long. Drivers must come to a near-complete stop to cross comfortably.
- Speed humps
Raised elements about 3 inches high and 12 to 14 feet long. They enforce speed reduction to 15 to 20 miles per hour.
- Speed tables
Raised elements about 3 inches high, with a flat top 20 to 25 feet long. Drivers must slow to about 15 to 20 miles per hour to cross.
- Speed cushions
Speed bumps or humps can be installed in a speed cushion configuration, where gaps are cut out from the raised area to allow for wider-axle emergency vehicles to pass through unimpeded.
- Raised crosswalks
A speed table placed where pedestrians crossed, often painted in a zebra crossing pattern.
- Raised intersections
An intersection with the entire center square raised by about 3 inches.
Vertical deflections are commonly used in local roads, lanes, and parking lots to slow speeds in low-volume traffic areas. They are effective at enforcing speed reduction; speed bumps and speed humps (aka speed cushions) are often called “sleeping policemen.”
On the other hand, they aren’t always welcomed. Critics say they can damage vehicles, slow emergency response time, and increase noise in the surrounding neighborhoods.
Municipalities can mitigate these effects by considering placement (speed cushion or slalom configuration, for example, can allow emergency vehicles to pass through without losing time), material (a softer material such as rubber can reduce the impact on the undercarriage of cars), and visibility (painting and signage can alert drivers to slow their speed in advance of hitting the bump).
Like vertical deflections, horizontal deflections are built into the road to force drivers to slow down. Instead of going over them, however, drivers must alter their course to traverse around them.
- Traffic circles
Also called roundabouts, traffic circles are an alternative to stop signs at intersections, allowing drivers to reduce their speeds, but pass through without stopping if the circle is clear.
- Chokers, chicanes, and curb extensions
Municipalities can build curbs that bulge out from the sidewalks to reduce the width of the street. If they are mid-block and narrow the road from either side like a bottleneck, they are called chokers. Chicanes alternate down the block, causing the road to effectively curve. Curb extensions are bulges at intersections that increase the amount of space for waiting pedestrians.
- Pedestrian islands (or refuges)
Raised “islands” can be built into the middle of the road, usually between opposing directions of traffic. These give pedestrians a place to pause safely in the middle of the road, especially on non-light-controlled crosswalks, as well as reduce the road width.
Horizontal deflections do result in slower vehicle speeds, particularly on moderate volume roads. They can also make the neighborhood more walkable, and provide greenspace. For low volume traffic, however, they are not as effective. Horizontal deflection is also inconvenient on roads servicing transit or with bike lanes.
Signage and Road Markings
Signage and painted road markings are a simple way to remind drivers to use caution. Signs can post messages such as “Children at Play,” or signal speed bumps or detours. A more recent and effective measure is the radar sign, where drivers’ actual speeds are posted directly above the speed limit.
Painted road markings are used to mark crosswalks (either painted lines along the boundaries, or “zebra” crossings), and to signal speed bumps and humps. They can also direct drivers: SLOW is frequently painted directly on roads, and hatched markings (diagonal lines) show spaces where cars shouldn’t drive.
Both signage methods are relatively inexpensive to install and maintain. They are effective in the short term; however, studies show that drivers become accustomed to the signage over time. Once the novelty wears off, most drivers revert to their original speeds.
To minimize speeding recidivism, signage methods are best used in combination with other traffic calming techniques.
Municipalities can install barriers to physically block drivers from entering certain spaces, such as bike lanes. Bollards are one of the most common barriers, allowing for bikes and pedestrians to safely cross through and navigate around them, while effectively blocking car traffic. They can divide the road from bike lanes or sidewalks, provide an extra safety barrier around corners as pedestrians wait by the crosswalk, and cut off vehicle access from pedestrian- or cyclist-only streets.
Bollard alternatives include planter boxes, trees, and jersey barriers (the modular concrete or plastic barriers that divide opposing directions of traffic on highways).
While physical barriers can and do make areas safer, they aren’t very good at getting drivers to reduce their speeds.
Like physical barriers, providing non-vehicle spaces don’t directly require drivers to reduce their speeds. Narrower roads, however, do require more caution from drivers. Roads can be narrowed due to a few types of non-vehicle spaces:
- Wider sidewalks
- Bike lanes
- Dedicated pedestrian spaces
Though not technically non-vehicle, adding roadside parking can also decrease the width of the available road and cause drivers to lower their speeds. These measures are usually best implemented when creating roads however, and can be difficult and expensive to install on existing streets.
Where Traffic Calming is Used
Traffic calming techniques are not used on all roads; they are primarily intended for local roads and lanes, where the demand for safety — for children, pets, joggers, and plain old pedestrians — outweighs the benefits of fast travel.
Collector and arterial roads with high volumes of traffic should not be fitted with physical measures, as they can contribute to congestion. Over-restriction of arterial routes can even backfire, causing drivers to overuse local roads in an effort to skip the traffic.
Transit routes and main emergency response routes should also have limited restrictions so that busses and emergency vehicles can move freely.
That said, overuse of traffic calming is rarely an issue — quite the opposite. Speeding is still a major issue in most cities. Traffic calming is a simple and practical way for us to make the streets safer.
How to get traffic calming in your neighborhood
Each municipality has their own process for requesting traffic calming in a neighborhood. The general process is as follows:
- Petition your neighborhood residents, or bring up the topic at a local public meeting.
- The municipality will conduct a traffic operations review, considering the type of road; measuring the traffic volume, speeds, and rate of accidents; and the most suitable measures for traffic calming.
- If the review concludes that traffic calming measures are appropriate, they will design the project and report it to the City Council, who must approve it.
- If the project is approved, a road alteration by-law will be passed, and the traffic calming measure will be scheduled for construction depending on season, priority, and budget.
- Finally, the traffic calming measure will be installed.
This is just a general overview; check your local municipality’s website as they will often have a “how to request traffic calming” section.
There are many traffic calming measures that both encourage drivers to go slower by making it more difficult to speed. At the same time, lower vehicle speeds and less volume of traffic also often make neighborhoods more pleasant. When people feel safer and more comfortable, they tend to walk and cycle more — compounding the benefits.
The traffic calming measures discussed vary in cost, scale, and suitability. Due to the range of options, however, there is an option to calm traffic and improve safety in any community.
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