I've been thinking about this post for a while and finally had some time to get the pictures and numbers needed to get the point across. Walkable cities and places prioritize pedestrians and make walking easy throughout the city. Livable cities succeed in making life possible for more than just the healthy adult population.
The measuring stick of true livability should be whether an 8 or 80 year old can easily navigate around without the need of a car or chauffeur. Most of our suburban and even urban environments in this country don't pass that test. One of the biggest obstacles that impede livability is simply the ability to easily cross a street.
I conducted a quick test to see just how long it takes an adult male, perfectly capable of navigating almost any city environment, to cross several intersections around Historic Roswell on foot. My measurement stick was the number of steps it took to go from sidewalk to sidewalk.
It's pretty obvious to tell which spots prioritize livability and walkability and which ones prioritize automobile traffic. Now, let the wonkiness begin. There are two primary impediments to walkability that are displayed in these examples. One that was illustrated above being the Crossing Distance. The other very geeky one is the Curb Return Radii (CRR).
CRR is essentially the radius of the curb and impacts the crossing distance at intersections as well as the speed of turning cars. The larger the radius, the faster you can negotiate the turn in a car and the farther you are going to have to walk to cross the intersection on foot. Here's a graphic of the CRR at several intersections around town. Which ones do you think are the most pedestrian friendly?
The smallest radii examples above are at Plum St and Canton Street and surprisingly at the NW corner of Norcross St and Frazer St. The largest is the entrance to the Roswell Landings condos along Norcross St which is also roughly the same as the turn from Holcomb Bridge Rd on to Warsaw. There's obviously a big difference in the type of traffic and the type of vehicle that frequently makes the turn into Roswell Landings vs the turn onto Warsaw.
The point being, that our intersections need to be designed with the context in mind. The Roswell Landings entrance is completely out of context with an entrance to a development in our historic district.
Even the Institute of Transportation Engineers agrees... I think. The ITE manual states the following about CRR:
General principles and considerations regarding curb return radii include the following:
- In walkable areas, the first consideration is keeping crossing distance as short as possible. Consider alternatives to lengthening the curb radius first, then consider lengthening the radius if no other alternative exists.
- Curb-return radii should be designed to accommodate the largest vehicle type that will frequently turn the corner (sometimes referred to as the design vehicle). This principle assumes that the occasional large vehicle can encroach into the opposing travel lane as shown in Figure 10.8. If encroachment is not acceptable, alternative routes for large vehicles should be identified.
- Curb-return radii should be designed to reflect the "effective" turning radius of the corner. The effective turning radius takes into account the wheel tracking of the design vehicle utilizing the width of parking and bicycle lanes. Use of the effective turning radii allows a smaller curb-return radius while retaining the ability to accommodate larger design vehicles.
If we are to believe what the ITE is stating above, then I think we should be seeing either the maintenance of our existing crossing distances or the reduction of them over time. However, I truly doubt that is happening, has happened or will happen. Looking at the example of the Norcross, Frazer, Forrest intersection in the image below, you can see that the older corners on the NW and SE of the intersection maintain their low CRR. However, the newer corners on the NE and SW have much larger CRR making it easier for cars to speed through turns and making it more difficult for pedestrians to cross the street.
I am making the prediction now that as the SE and NW corners of that intersection get redeveloped in the coming years, this intersection will lose it's form and become a typical intersection that gives priority to the car by increasing the CRR and Crossing Distances.
This isn't just a problem at intersections along our streets and roads. New developments are often required to have ridiculous CRR on their interior streets to accommodate larger vehicles such as fire trucks. Here's an image of one of the new developments going in along Myrtle St in the Groveway district.
The CRR pictured here are ENORMOUS. They are larger inside the development than they are where the development meets Myrtle St. What we are doing here is increasing the everyday danger of cars speeding through curves inside neighborhoods where people aren't expecting speeding cars in order to slightly improve the response time for First Responders in the off event of a fire.
So, if the ITE says the first consideration is keeping crossing distance as short as possible, then WHY are our intersections getting harder and harder for pedestrians to cross.