Traffic Calming in Greenville SC

By Dom Nozzi

Regarding speed humps…

I am possibly the biggest advocate in South Carolina for using traffic calming devices on streets, as I believe slowing cars is one of the most important things we can do in cities for better safety, quality of life, reduction in low-value motor vehicle trips, and noise reduction.

Speed humps, however, are an exceptionally problematic tool for slowing cars. On the list of bad ideas for slowing cars, speed limit signs are at top of the list for being the worst. Stop signs are about as bad. And humps are #3 for being a bad tool.

Here is why humps are a bad idea:

They punish motorists even if the motorist is driving fairly slowly.

They can damage vehicles.

They create noise pollution for neighborhoods.

They create problems for emergency response vehicles.

They are annoying for cyclists.

When spaced improperly, they promote “jackrabbit” driving (ie, frequent slowing and speeding between humps).

An important reason why many cities such as Greenville use (or overuse) humps so often (there are way too many humps in Greenville) is that they are very quick and low-cost to install. Which makes them an easy way for elected officials to satisfy neighbors concerned about speeding vehicles.

However, the best way, by far, to slow motor vehicles is not to use “vertical” interventions such as humps, but to use “horizontal” interventions. Examples of horizontal interventions include:

1.       Road diets, where excessive street lanes are removed. The most common diet is going from 4 lanes to 3.

2.       Landscaped or hard-surface bulb-outs (usually used to frame on-street parking or create a mid-block pedestrian crossing). Many bulb-outs are admirably used on Greenville’s Main Street. Ideally, this “pinching down” the width of the street creates a one-lane-wide pinch point that obligates motorists to “give-way” when a motor vehicle approaches in the opposing direction.

3.       Chicanes, which are a form of bulb-out that obligates motorists to move in a slower, weaving, more attentive pattern.

4.       Traffic circles and roundabouts.

5.       Installing on-street parking on streets without such parking. Again, this narrowing of street width works best when a “give-way” street is created.

6.       Installing formally-aligned street trees abutting the street to create a sense of enclosure and human scale.

Each of these horizontal interventions is much more conducive to bicycling and emergency response vehicles than vertical interventions such as humps. They are also much better at creating a safe environment for walking. As well as created the much-needed human scale and sense of place that is lost when we oversize streets and intersections.

On my list of top priorities for Greenville to become a better city, traffic calming is near the top of the list. But calming needs, again, to be achieved with horizontal rather than vertical interventions.

Permanently Pedestrianize Pearl?

By Dom Nozzi

The Boulder Colorado City Council recently considered permanently closing Pearl Street west of the Mall.

One response to the pandemic on Pearl Street has been to allow retailers to expand into public streets and sidewalks. In the case of Pearl Street west of the Mall, this has included closing the street to cars.

While I largely support these reforms, I would urge caution. Yes, the idea of reallocating space on Pearl Street to move away from exclusive car use is long overdue and would achieve important benefits. But there are a few likely negative outcomes.

A lot of us “put people before cars” folks will see the idea of closing Pearl to cars  beyond Pearl St Mall as irresistibly seductive.

I’m not so sure.

Urban designers know that prohibiting cars on more than a few blocks is almost always fatal to retail UNLESS there is sufficiently compact mixed-use development along the street. Pearl is far less compact than is needed to support more closure.

Another worry: one suggestion is to reallocate space from cars is to make Pearl a one-way street. One-way conversion was popular in the 60s and 70s, but we now know they are terrible for a town center – particularly for retail. A growing number of one-ways are therefore being converted back to two-way.

Even with a pandemic crisis, it is politically difficult to close streets to cars.

Fortunately, there is a Third Way.

A compromise that would offer enormous benefits, be relatively feasible politically, promote retail health, retain fire truck access, and enhance public health (from both added social distancing space and boosting the amount of walking and bicycling) is a “woonerf.”

I believe the woonerf is a “Third Way” design. It creates a low-speed street design on Pearl – a “living street” safely shared by cars, pedestrians and cyclists (Google “woonerf,” or go to https://en.wikipedia.org/wiki/Woonerf). Woonerfs can be installed quickly, relatively cheaply, and temporarily if they do not work out.

Some people call such design “give-way” streets, where the two-way street is so narrow that the motorist must “give-way” to an on-coming car.

Low-speed design would allow two-way car travel to continue on Pearl, but would obligate motorists to drive very slowly (say, 10-15 mph) and very attentively. So much so that even children and seniors would be safe and happy to sit in the street or walk or bicycle in the street.

I recommend the woonerf treatment for Pearl west of the Mall to 9^th Street and east of the Mall to, say, 19^th Street.

How is a low-speed two-way street created? On Pearl, it would mean removal of the awful design decision of a continuous left-turn (suicide) lane in the middle of the street. That alone allows ample space reallocation.

Second, shrink the width of the travel lanes to, say, 9 feet each. Also shrink the height of signs and street lights to create a “low-speed ambiance.” Add street furniture, and plenty of new green tree, shrub and flower landscaping in elevated “planter” boxes to the street (exactly the way it was done on Pearl St Mall, by the way).

Woonerfs typically eliminate curbs and elevated sidewalks to signal that the street is slow-speed and shared between cars, cyclists, and walkers. By doing each of these things, we would create an extremely safe, happy, vibrant Pearl Street that prioritizes people (cyclists, peds, seniors, children) over cars without eliminating cars.

Cars, as is the case in Dutch woonerfs, are able to remain but they are obligated by the street design to be very slow speed and safely attentive. Retail and restaurant businesses would flourish with the big increase in space, and the much slower speeds by motorists (who, because they are driving more slowly, are more likely to stop and be customers).

The new street design would lead to a jump in the number of pedestrians and cyclists on Pearl Street who were previously too worried to walk or bike there due to the pro-car design. By allowing slow-speed cars, a woonerf allows a city with insufficient compactness to deliver sufficient customers to businesses along the street.

Woonerf

So yes! Let’s reallocate space on Pearl so that it is pro-people rather than pro-car. But let’s do it right, and avoid the mistakes of the past.