Should This Intersection Be a Roundabout? Should Any?

Should this intersection be a roundabout?

(Google Earth screen capture)

The four-way stop at Forest Drive and Cottage Grove Avenue, right by Washington High School on the southeast side of Cedar Rapids, has twice had roundabout proposals rejected. A third bite at that apple is therefore unlikely, but is that a good thing? Anyway, roundabouts are the pumpkin spice of the street design world right now, with strong feelings on both sides, and therefore we must have an opinion. Might as well be an informed one.

We can move the conversation along a little by noting roundabouts are likely to be useful (if still controversial) in some places and not useful in others. A roundabout at the intersection of U.S. 30 and State Route 1 outside of Mt. Vernon untangled a problematic intersection. Commonly-cited advantages of roundabouts compared with traffic lights are they move vehicle traffic more efficiently while lowering their maximum speed (a win-win!), with fewer injuries, cost less, and aren't subject to power outages. Strong Towns (2018) notes that “roundabouts can even out traffic flow compared to typical signalized intersections which tend to create stop-and-go lineups of cars. But whether they can relieve truly congestion depends on what is causing it…” The "Mythbusters" show even found roundabouts moved traffic better than four-way stops (see Ihnen 2013, Gursten 2014).

Forest and Cottage Grove are in town, about two miles from the city center. Cottage Grove had an average daily traffic count of 5800 in 2017. (Forest Drive’s count hasn’t appeared on the map since at least 2009.) The main traffic issues, though, occur at the beginning and end of the school day, so roughly 7:30-8 a.m. and 2:30-3 p.m. 

The location of the high school at that intersection means that we’re anticipating cyclists and pedestrians as well.  Here the Internet is frankly not encouraging. For cyclists, the Iowa Department of Transportation advises:

Bicyclists have a legal right to ride on most roadways just like motorized traffic. Roundabouts are just like other intersections in that bicyclists may either follow the rules of the road and maintain travel on the roadway or use available paths and crosswalks to safely bypass the roundabout.

The New York Department of Transportation adds these tips:

1.     If you are comfortable riding in traffic, take the lane and circulate like you are a vehicle, making sure you yield to traffic in the circle when entering.

2.     Ride at the speed of the circular roadway to discourage cars from passing you.

3.     When you exit the roundabout, use your right hand signal.

4.     If you are uncomfortable riding through the roundabout, dismount and walk your bike as a pedestrian at the designated crosswalks.

But it’s one thing to have “a legal right,” it’s quite another to feel safe exercising it. Indeed, a 2021 review of 49 studies mostly from Europe found:

Crash data and observations suggest that when cyclists “take the lane” and operate as vehicles – as is allowed or even recommended in some current design guidelines – this leads to conflicts and crashes between circulating cyclists and entering drivers who may have “looked but failed to see” (and thus failed to yield to) the cyclist.

They conclude that discretion is the better part of valor.

Providing separated cycle paths around the roundabout seems to be a lower-risk and more comfortable design solution, although care must be taken to encourage appropriate yielding at crossings.

This makes sense, though a series of intersections at which diversion is required is going to get frustrating, resulting in either more aggressive cycling or no cycling at all, neither of which are outcomes we should desire.

Satisfactory solutions for pedestrians are also elusive. The Iowa Department of Transportation recommends:

Pedestrians should always use the crosswalks; and make sure the vehicle operators see him/her before entering the crosswalk.

This seems reasonable enough, but this video from Minnesota-based traffic engineers Stonebrooke…

…shows that we are expecting pedestrians to wander out of their way to find the crosswalk, and expecting vehicle drivers to stop for them when they ask to cross. We are expecting strollers to go straight while we push them with one arm while holding the other one out for all to see, and we are expecting we will not feel silly doing that. Good luck, with all of that.

Strong Towns (2016) allows “a roundabout can provide good, safe crossing opportunities for pedestrians, but only if engineers have pedestrians and bicyclists in mind when they design the roundabout…” This means (1) single-lane roundabouts not multi-lane, (2) not having pedestrians cross lanes with “particularly heavy” exiting volumes, (3) maintaining clear sight lines for drivers, (4) locating crosswalks away from the circle itself, (5) pedestrians signals to accommodate blind pedestrians, and (6) beaucoup public education.

They also note all this works “only if drivers use them properly.”

For this reason, Jeff Speck (Walkable City Rules, Island Press, 2018) wants roundabouts out of urban areas.

There are a number of features that make roundabouts feel less walkable than traditional intersections. 

• First, they ask people who are trying to walk in a straight line to divert well to the side, and then back again, in order to keep moving across town. 
• Second, while they require cars to slow and yield to pedestrians, vehicles never actually come to a full stop unless something is blocking them; roundabouts feel dynamic, and pedestrians prefer environments that are static. 
• Third, they introduce into urban areas a design vocabulary which is unavoidably automotive; they swoop. (2018: 164-165, bullets added)

But our intersection isn't in an urban downtown, it's two miles away by a high school. Traffic is heavy for half an hour to an hour on school mornings and afternoons, and light the rest of the day. I think the roundabout might be highly functional 22-23 hours a day: drivers on either street could proceed without having to come to a full stop, and pedestrians might be glad to have them out of the way quicker.

It's those brief periods when traffic through this intersection is heaviest that give me pause. Moreover, it's heavy with inexperienced drivers taking themselves to school. Not many people walk to the high school; as Cedar Rapids schools get bigger and more spread out, fewer students walk. However, because of where the stop is located, city bus riders must also cross both streets to get to the school. As confusing as four-way stops can be, would people on foot be more confident getting across the street if cars were not coming to full stops?

We can hope for more pedestrian and cyclist traffic in the future. Just because the area isn't urbanized now, there's no reason that it should never be, given its proximity to the city center and development on 1st Avenue. A federal Safe Routes to School grant was recently used to build a wide sidewalk through this very intersection that coincidentally links the Interurban and CeMar trails. Does, or could, this encourage more walking and cycling, at all times of day?

Bottom line: There would be certain advantages to putting a roundabout here, but its effect on pedestrian and cyclist behavior now and particularly in the future tells me we shouldn't do it.

Where Should We Build Roundabouts?

So, are we dissing all roundabouts? By no means! That would be the sort of reflexive know-nothing opposition for which Boomers like me are so famous, and we can't support that. So, let's look for some intersections where (a) there is a complex intersection of two high-traffic streets; (b) there is currently a traffic light; and (c) it is not nor is it likely to become an urbanized area.

This town is replete with intersections possessing all three of those conditions, and so is your town, because of the way we've all been developing for 50-75 years. I'd look in the same concentrated commercial areas I visit for Black Friday Parking:

• 1st Avenue and Collins Road E
• Council Street and Collins Road NE
• 16th Avenue and Williams Boulevard SW
• Edgewood Road and Williams Boulevard SW
• Edgewood Road and Blairs Ferry Road NE
• probably a lot more, but these would be towards the top!

SEE ALSO: "When Are Roundabouts Indicated?" 2 August 2018

Kai Ryssdal and Nicholas Guiang, "Don't Panic, It's Just a Roundabout," Marketplace, 22 December 2022

Extreme roundabouting: (I am absolutely not recommending this!!)

When are roundabouts indicated?

Strange intersection north of Coe College campus. Is a roundabout the solution?

Construction of roundabouts is "exploding" around the State of Iowa, according to Steve Gent, who is director of traffic and safety for the Iowa Department of Transportation (Morelli 2017). Cedar Rapids recently got into the game with a redesigned intersection of Kirkwood Boulevard and 76th Avenue SW, and will soon get two more on Johnson Avenue SW. All these roundabouts come with many promises of improved traffic performance, and much public angst about the introduction of this unfamiliar traffic feature. Our task today is to decide when roundabouts might be a positive addition, and where they might be overdone.

Roundabout schematic (Source: U.S. Dept of Transportation)

A roundabout is a circular intersection characterized by small diameters (relative to traffic circles like Columbus Circle and DuPont Circle in Washington, D.C.); curvature designed to slow speeds; a center island around which traffic turns; and the requirement for entering drivers to yield to those already in the circle (USDOT 2000: 5). Conceptual or real operation can be seen in the videos listed below. Benefits of roundabouts include:

• improved traffic flow despite slower traffic speeds, because vehicles are moving at a slow steady pace instead of alternating stopping and going fast;
• less pollution, at least at the intersection site, because the cars keep moving;
• improved safety because there are fewer contact points and all cars are going in the same direction; 
• lower year-to-year costs than a traditional signal because those require electricity and maintenance (though construction costs are higher).

St. Paul, MN: Intersection of Charles and Albert Sts is more properly called a "neighborhood traffic circle"

The disadvantages of roundabouts stem from their unfamiliarity in much of this country, outside of the Northeast. Drivers' uncertainty can create more problems than the feature is designed to solve, particularly in a two-lane roundabout where the required lane changes seem to guarantee mass confusion (see second diagram here). Tom Vanderbilt argues that's a feature, not a bug:

With a roundabout, only a fool would blindly sail into the scrum at full speed [as opposed to the common maneuver of speeding through a yellow light]. Drivers [entering a roundabout] must adjust their speed, scan for openings, negotiate the merge. This requires more workload, which increases stress, which heightens the feeling of danger. This is not in itself a bad thing, because intersections are, after all, dangerous places. [From the previous page: 50 percent of all road crashes occur at intersections.] The system that makes us more aware of this is actually the safer one. (2008: 179)

Cultural hostility to change, whether it involves sidewalks or LED light bulbs or the metric system, gets magnified when it hits us where we live, and a lot of us live in our cars. Elected officials are understandably chary of triggering this hostility. Additionally, there is the cost of conversion, estimated at $1.2 million (Morelli 2017), which is about four times the cost of installing a set of traffic signals, and way more expensive than a four-way stop. Finally, there is disagreement over whether bicyclists and pedestrians benefit from this design.

Newly-built intersection of 5th St and 16th Av SW includes a roundabout:
anticipation of future traffic, or vanity feature?

Roundabouts and traffic circles are commended as traffic calming measures in David Sucher's manual for city-building. He explains:

[Roundabouts are] not so much to slow down traffic but to allow movement through intersections without having to stop.... A slow but steady pace would achieve the same overall time from origin to destination but without the mental aggravation of continual acceleration, braking, stopping, and then accelerating again. (2003: 79; see also Vanderbilt 2008: 124)

He cautions, however:

The traffic circle is not manna. Some drivers loathe them and will change their route to avoid them, which may serve to decrease traffic on one block, only to divert it to another, increasing traffic there. (2003: 78)

The main trick with roundabouts is to keep traffic flowing without creating disconnection between the parts of the city on either side. From this we might conclude that roundabouts are indicated where traffic volume is great enough to overwhelm a four-way stop; the volume of turning traffic would require a separate turning light, making the overall light cycle painfully long; and pedestrian and bicycle traffic is manageable. There should be regular breaks in the traffic, so that new entrants can merge easily--unlike Chevy Chase's experience in "National Lampoon's European Vacation!"--pedestrians can get through the intersection in a timely fashion, and cyclists can cycle.

[The Iowa Drivers Manual (cited below) recommends "Generally, cyclists should walk their bicycles across the pedestrian crosswalk using the same rules as pedestrians," though it allows that "Experienced cyclists may navigate roundabouts like motorists." If the traffic feature in an area with significant bicycle traffic depends on cyclists getting out of the way, it is doomed to failure. The idea of urban design is that it accommodates and channels normal human behavior, rather than presuming that one set of travelers is voluntarily going to withdraw from the scene.]

Pair of roundabouts on U.S. 30 south of Mt. Vernon (Google maps)

On roads roundabouts can be focused on traffic flow. One successful roundabout near Cedar Rapids is at the intersection of U.S. 30 and S.R. 1 in Mt. Vernon. It used to be a four-way stop, featuring long backups at most times of the day. With the roundabout we sail right through, though I confess I haven't tried it during rush hour. There's another roundabout to the west where U.S. 30 intersects 10th Street. When I drive through, it seems unnecessary because of the lack of traffic off 10th Street. I understand that traffic occurs mainly at school drop-off and pick-up times, and that there had been a substantial number of crashes there. I don't know that the roundabout was the best solution--maybe cars needing to go east on U.S. 30 could have been guided to S.R. 1--but I don't know that it wasn't. A student from Mt. Vernon reports that every member of the City Council who voted for the roundabouts was defeated at the next election, which speaks to the fraught political climate around this issue. The American Society of Civil Engineers reports the outcome eventually got happy; they quote Justin Campbell, a transportation engineer on the project: Now that the roundabouts are finished and working, people are happy. The cars are moving (Wilcox 2016).

Other than the ones on U.S. 30, the Linn County roundabout that gets the most use is unquestionably the one west of downtown ("Uptown") Marion, at the intersection of 7th Avenue, 7th Street, and 6th Avenues. (An indication of the current rage for roundabouts is that an Internet search for "Marion roundabout" finds stories from Illinois, Indiana and Kansas as well as Iowa.) It opened November 2016 as part of Marion's Central Corridor Project, intended to divert through traffic off 7th Avenue onto 6th and allow 7th to become the hub of a walkable urban district (Kasparie 2016). It is no longer possible to go through the intersection southbound on 7th Street, or westbound on 6th Avenue, though it's not clear how many people were previously doing this.

Traffic moved briskly through the roundabout this morning while I observed it from 7:45-8:30 a.m. Most people drove with confidence, even though the feature is barely a year and a half old. There occasionally appeared to me to be hesitation entering the circle, but nothing that delayed traffic more than a few seconds. Only one driver was yielding to traffic entering the circle, and two drivers--both talking on phones--were observably erratic.

Most traffic this morning was headed west along 7th Avenue i.e. towards Cedar Rapids, and I saw the only mild backups on westbound 7th approaching the roundabout, a string of six and a string of seven cars behind semi-trucks that had had to stop before entering the circle. There was more traffic on 7th Avenue than on 8th Avenue, so no evidence that traffic was diverting away from the roundabout. I'd heard reports from a local student that backups occasionally occurred when a line of cars proceeded north on 7th Street and had to stop at 8th Avenue...

...but I never saw more than one car going in that direction this morning. Country Kitchen Cafe was doing a brisk business on the southwest edge of the circle...

...though I'd be interested to compare their before-and-after numbers. Very few pedestrians or cyclists came through while I was observing. The cyclist used the sidewalks and surprised a driver when he turned left across 7th Street. Few eastbound cars bypassed the commercial area on 7th Avenue by diverting to 6th Avenue, but 6th isn't yet complete around Uptown. Overall, I'd say traffic was moving, quite likely better than it did when the intersection was governed by a set of traffic lights.

So, bottom line: Should the complex intersection north of Coe (pictured at top) be redone as a roundabout? It would certainly facilitate conversion of the streets to two-way, and would seem not to stand in the way either of better development of the area, or of increased pedestrian activity. Here would be something that's broken, and a roundabout would be one, perhaps the best, way to fix it.

VIDEOS
Bicycle Dutch, "A Bicycle Roundabout in Boxtel (Netherlands)," (YouTube, 3:16)
City of Cedar Rapids IA, "Simulation Video of Johnson Avenue NW Roundabouts" (YouTube, 1:29)
Insurance Institute for Highway Safety, "How Roundabouts Work" (YouTube, 2:00)
Charles Marohn, "Pimped Out Roundabout" (YouTube, 2:51)
Thorsten Peters, "Laweplein 02" (Vimeo, 1:47)

SOURCES
"Hans Monderman's People-Friendly Dutch 'Squareabout,'" ThinkBicycling, 13 June 2013
David Hembrow, "Where the Crashes Are: Shared Spaces and Other Poor Junction Designs Which Don't Protect Cyclists Lead to Crashes and Injuries," A View from the Cycle Path, 7 April 2014
Jill Kasparie, "Marion Prepares for Work to Begin on Roundabout Projects," KCRG.com, 15 March 2016
B.A. Morelli, "Cedar Rapids Gets Its First Roundabout as Traffic Tool 'Explodes' Around Iowa," Cedar Rapids Gazette, 9 June 2017
David Sucher, City Comforts: How to Build an Urban Village (City Comforts, rev. ed., 2003)
U.S. Department of Transportation, Roundabouts: An Informational Guide (USGPO, 2000)
Tom Vanderbilt, Traffic: Why We Drive the Way We Do (and What It Says About Us) (Alfred A. Knopf, 2009)
Kevin Wilcox, "Iowa Roundabouts Go with the Flow," Civil Engineering, 12 April 2016

And finally...

...because I've been humming it the whole time I've been writing!