Here’s where CDOT could pilot real protected intersections to keep cyclists safe

A protected intersection in Rotterdam. Photo: Ralf Roletschek via Wikipedia
A protected intersection in Rotterdam. Photo: Ralf Roletschek via Wikipedia

Bike lane advocacy in Chicago tends to focus on whether a bike lane is “protected” or not. But too often on this city’s streets, a well-protected bike lane disappears before the intersection. Bike riders are forced to share space with right-turning drivers in “mixing zones” at intersections that neither look good on paper nor work well in practice.

Most crashes between people biking and and driving occur at intersections, so protecting cyclists as they ride through the junction is crucial. The solution is a protected intersection. These were invented by the Dutch, but have spread around the world and are even beginning to pop up here in the U.S.

The protected intersection is a little tricky to wrap your head around, but in practice biking through one is very intuitive. As one cyclists said, “It just works.” Here’s a “view from the handlebars” video from Mark Wagenbuur of Bicycle Dutch turning left and right through a Dutch protected intersection that will give you a better sense of what it’s like.


A protected intersection follows three principles:

  1. Even though they must eventually cross paths, drivers and bike riders should be kept separate as much as possible
  2. When they do cross, they should cross at right angles for better sight lines
  3. Everything is safer when it happens at low speed

Let’s take a look at a typical intersection for a Chicago protected bike lane – and then sketch out how to make it into a protected intersection.

55th and Ellis in Hyde Park, looking west. Image: Google Maps
55th and Ellis in Hyde Park, looking west. Image: Google Maps

Here’s an intersection I ride through all the time, at 55th Street and Ellis Avenue in Hyde Park, heading west. (There is also a bus stop here, but intersections on this street without a bus stop have a similar design so we’ll cover bus stop treatments in a future article.)

Aerial view of 55th and Ellis. Image: Google Maps
Aerial view of 55th and Ellis. Image: Google Maps

The first thing to notice is that the physical protection ends 107 feet before the stop line, and the total distance that the bike lane is unprotected is 218 feet. That’s about one-third the length of a typical 660-foot Chicago block! So a person riding in this “protected bike lane” is actually exposed about one-third of the time.

The second thing is that right-turning drivers have to merge with the bike lane in a very dangerous way. The merging motorist has just cleared a line of parked cars, so neither cyclist nor driver can see each other until right at the merge point. And at the angle the driver enters the shared lane, the cyclist is in their blind spot. While the law here is the driver must yield to the bike bike rider, the reality is the cyclist must yield or risk injury.

Image: Google Maps
Image: Google Maps

And finally, with the shallow angle of the merge, the driver could easily enter this lane at 30 or 35 mph, a speed which makes a collision both more likely and more dangerous.

Ok, let’s fix this! The first step is to follow Principle 1 and keep the drivers and bike riders separate as much as possible, by adding curbs, black in the image below.

Image: Steven Lucy via Google Maps
Image: Steven Lucy via Google Maps

The easiest thing to do is just keep the bike lane protected by a curb until the crosswalk and not have it merge with the right turn lane in a mixing zone. I measured, and there is room for a 11-foot-wide through lane, a 10-foot turn lane, a 1-foot curb, and a 5-foot bike lane without moving any existing curbs. Doing this would immediately reduce the length of exposure from 218 feet to 74 feet and also prevent drivers from illegally parking in the bike lane.

This design is a big improvement – it cuts by two-thirds the exposure distance, eliminates the merge danger, and physically blocks illegal parking. But it does present a serious “right hook” danger, where a driver turning right hits a person biking, or a bike rider going straight hits the side of a turning car.

That’s where principles 2 and 3 come in. We want the person driving and person biking to approach each other at a 90-degree angle so they can both see each other. And we want to slow the driver down a lot and the cyclist down a little bit so they have more reaction time – and so that any collision that does occur happens at a low speed and is less dangerous.

Let’s do it!  To the above design we add the corner refuge island – the signature of protected intersections:

55th and Ellis with Corner Refuge Islands added. Image: Steven Lucy via Google Maps
55th and Ellis with corner refuge islands added. Image: Steven Lucy via Google Maps

The corner refuge island is a simple bit of concrete, but the way that drivers and cyclists interface with it is actually quite complex, so let’s break down the advantages.

First, the length a cyclist must go without protection is shortened even further, to about 33 feet. That’s 85 percent shorter than the original 218 feet of exposure, so a pretty big improvement. Before, on a 660-foot block, you were exposed about a third of the time.  Now it’s more like 5 percent.

Second, drivers turn almost the full 90 degrees before they cross the bike lane. People on bikes can see the driver coming, and the motorist can see the bike rider through their windshield, rather than having to check their mirrors.

Third, drivers turning right have a tight turn and must slow down, usually to 10 mph or less. Bike riders have a slight wiggle to the right and then back left again, which slows fast cyclists (or e-bike riders) down to the 10-15mph range. Granted, this slalom might be a little annoying for some people on bikes who are in a hurry, but I’d argue that the safety benefit is worth it.

Milwaukee and Elston in Wicker Park. Image: Google Maps
Milwaukee and Elston in Wicker Park, looking north. Image: Google Maps

Let’s take a look at another Chicago intersection, the junction of two streets with protected bike lanes: Milwaukee and Elston Avenues in West Town. The Chicago Department of Transportation was aware of the right-hook danger here, so they put in a dedicated signal phase for northwest-bound through bike traffic on Milwaukee when northwest-bound drivers are not permitted make a right turn onto Elston, although motorist compliance is not perfect. Here’s how that intersection looks now.

Aerial view of Milwaukee/Elston. Image: Google Maps
Aerial view of Milwaukee/Elston. Image: Google Maps

And here it is with a protected intersection treatment, without any reduction in travel lane width or the number of car parking spots.

Milwaukee/Elston with a protected intersection treatment. Image: Steven Lucy via Google Maps
Milwaukee/Elston with a protected intersection treatment. Image: Steven Lucy via Google Maps

Here, to reduce the crossing distance we also “twist” Elston so it meets Milwaukee at more of a right angle, which greatly increases safety both for drivers and bike riders. We also add a large central refuge island in addition to the corner refuge island.  Elston is about 50 feet wide here (curb-to-curb), so there is more than enough room.

To recap the advantages, for cyclists heading northwest on Milwaukee, we go from 129 feet of exposure to about 35 feet. Plus people on bikes only need to look for motorists coming from one direction at a time, and drivers will be approaching slowly and at a predictable high-visibility 90-degree angle.

For people biking southeast on Milwaukee, we go from 258 feet of exposure to zero. There isn’t even a cross street here, so there is no reason whatsoever to leave bike riders exposed to traffic without physical curb protection.

Washington/Franklin, looking east. Image: Google Maps
Washington/Franklin, looking east. Image: Google Maps

“But wait!” you may be saying, “Doesn’t Chicago already have a protected intersection treatment at the southeast corner of Washington and Franklin Streets in the Loop, where two bike lane streets intersect, that protects people biking north from northbound drivers turning east?” (There’s a similar treatment a few blocks at the northwest corner of Randolph and Dearborn streets, but right-hooks by drivers aren’t a possibility at that location.)

Kind of. The Washington/Franklin treatment, completed in December 2015, shares a similar format with a true protected intersection, but lacks some key features. 

An aerial view of Washington/Franklin. Image: Google Maps
An aerial view of Washington/Franklin. Image: Google Maps

Can you spot the differences? First, while the Washington bike lane is protected all the way up to the intersection by a Loop Link island bus station, the bike lane on Franklin leading up to the intersection is not protected at all! (It has parking to the right.)

Second, the corner refuge island is tiny.  A driver turning right here from northbound Franklin to eastbound Washington is forced to slow down, sure, but especially if they are turning into one of the far lanes, they don’t have to slow down much, and bike riders will still mostly be in their blind spot.

To be a true protected intersection, the Franklin bike lane needs to slalom further to the right, to where the pedestrian crosswalk currently is, so that drivers completes their turns before crossing the bike lane at a right angle.

In short, it wasn’t bad for a pilot, but it’s been over six years since then and we haven’t seen any iteration, improvement, or replication elsewhere in the city.

To get more people onto bikes (and improve safety for those already cycling), Chicago needs to stop doing incremental improvements like this at a glacial pace. We need to just build protected intersections that follow the Dutch layout, which we know work well, while massively increasing the miles of protected bike lanes built each year.

It’s not like this hasn’t already been done elsewhere in the U.S. Here’s a great example from Salt Lake City, implemented quickly and cheaply with planters and paint.

And here’s a more permanent installation in San Francisco from earlier this month:

In San Francisco, while there is concrete protection leading up to the intersection, the city opted for rubber speed bumps and flexible plastic posts for the corner refuge island. While that’s not as good as concrete, it forces most traffic to take the tight turn slowly, while allowing large trucks (and fire trucks) to drive over the island at a slow speed if necessary. In places where a full corner refuge island is not possible under current law, this is a good way of getting most of the benefits without abandoning the general format, as long as it comes with a commitment to replacing these elements when they are inevitably damaged. In Europe it is common to use low-curb concrete islands in these cases. Drivers of large vehicles can still drive over them if necessary, but they’re less likely to get destroyed by a snow plow operator.

In general, CDOT and and the Illinois Department of Transportation need to stop reinventing the wheel and just copy protected bikeway designs that work well elsewhere. Where creativity is warranted and welcome, though, is in finding ways we can quickly deploy known solutions like protected intersections without having to change existing laws or buy a whole fleet of smaller fire trucks. In these cases, creative solutions like we see in Salt Lake City and San Francisco are what we should be looking for from our transportation engineers.


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