TagLincoln Park

Revealing driver behavior on Clark Street with a radar gun

People prefer to cross Clark Street at Menomenee Street in groups of unacquainted individuals.

This is a more detailed post of the one at Streetsblog Chicago.

On the overcast morning of Friday, May 4, 2012, I recorded the speeds of 412 cars at four locations along Clark Street in Old Town and Lincoln Park for 15 minutes at each location. I missed counting the speeds of 42 cars. The embedded map shows the locations and some basic statistics.

What did I find? There’s a relationship between street width and the speed people drive. The highest speeds were found on the widest portions, and the lowest speeds on the narrowest portions. However, this basic study is far from scientific. A better study would record the locations simultaneously (necessitating 4 radar guns), calibrated equipment, consistent training for the researchers on data collection methods, a longer recording duration, and comparison to a control street that had a uniform width at four locations.


View Radar gun places on Clark Street in a larger map

1. Southbound Clark Street at Germania Place

My assistant and I set up the radar gun and camera immediately south of Sandburg Terrace and pointed the radar gun at people driving southbound on Clark Street between a row of parked cars at the concrete median (pedestrian refuge island). Classes would start soon at the Latin School on the east side of Clark Street. Compliance with state law requiring drivers to stop for pedestrians in the crosswalk was weak, to say the least, but compliance wasn’t explicitly measured.

  • Average speed: 17.21 miles per hour (MPH)
  • Maximum speed: 30 MPH
  • Cars measured: 151
  • Speed limit: 30 MPH
  • Drivers exceeding the speed limit: 0
  • Width: 224 inches (from west curb to pedestrian refuge island)
  • Effective width: 140 inches (excludes parking by subtracting 7 feet)
  • Crashes: 35, of which 4 were bicycle, and 3 were pedestrian.

Only one car-car crash (actually a 3 car crash) produced an injury. What’s interesting about this location is that in a lot of the crashes, the cars were traveling in the same direction. There’s a lot of school drop off and pick up activity here for Latin School of Chicago students, so it could be that many people are pulling away from the curb to merge into traffic and collide.

2. Northbound Clark Street at Menomenee Street

  • Average speed: 30.83 miles per hour (MPH)
  • Maximum speed: 50 MPH
  • Cars measured: 121
  • Speed limit: 30 MPH
  • Drivers exceeding the speed limit: 53.72%
  • Width: 395 inches (from east curb to dividing line). This includes the parking lane but no cars were parked within 50 feet, north and south, of the measurement location.
  • Crashes: 20, of which 2 were bicycle, and 1 were pedestrian. Many of the non-bike and non-ped crashes involved a parked car or taxi. The only injuries experienced were by the 2 cyclists and 1 pedestrian.

3. Northbound Clark Street at Lincoln Park West

We stood on the “pie” (traffic island) that separates northbound Clark Street traffic from northbound Lincoln Park West traffic to measure the traffic driving on Clark Street between the pie and the concrete median separating it from southbound Clark Street.

  • Average speed: 25.60 miles per hour (MPH)
  • Maximum speed: 40 MPH
  • Cars measured: 58
  • Speed limit: 30 MPH
  • Drivers exceeding the speed limit: 27.59%
  • Width: 252 inches (from concrete median curb to west curb on the pie)
  • Crashes: 4, of which 1 was bicycle, and 2 were pedestrian.

4. Northbound Clark Street between Lincoln Park West and Dickens Avenue

This location is 125 feet north of the previous location.

  • Average speed: 22.54 miles per hour (MPH)
  • Maximum speed: 35 MPH
  • Cars measured: 58
  • Speed limit: 30 MPH
  • Drivers exceeding the speed limit: 2.44%
  • Width: 264 inches (from east curb to dividing line).
  • Effective width: 180 inches (excludes parking by subtracting 7 feet)
  • Crashes: 0

Me measuring speeding drivers on Clark Street with the speed gun, my clipboard and paper, and a GoPro camera to record the speeding drivers and the results on the speed gun. 

Bike Walk Lincoln Park’s proposal

In 2011, Michelle Stenzel and Michael of Bike Walk Lincoln Park published a document to “Make Clark a Liveable Street“. The first two pages show an aerial photo of the same section of Clark Street where I measured automobile speeds, North Avenue and Armitage Avenue. On the first page, existing conditions are laid out. The second graphic shows proposed improvements.

At Menomonee Street, measurement location 2, the document says “pedestrians must cross 6 lanes with no safe haven”, a width of just under 66 feet. In the later pages, the first existing condition is blatant: “Wide lanes of auto traffic moving at speeds in excess of the speed limit”. My analysis in May demonstrates this.

How does BikeWalk Lincoln Park propose to “transform this stretch from a car-oriented ‘super-highway’ to a people-oriented liveable street”? By installing protected bike lanes, putting the street on a diet, and installing new and well-marked crosswalks among other ideas.

Width and speed summary

Ordered by location:

  1. 224/140 inches. 0% of drivers exceeded 30 MPH speed limit
  2. 395/395 inches. 53.72% of drivers exceeded 30 MPH speed limit
  3. 252/252 inches. 27.59% of drivers exceeded 30 MPH speed limit
  4. 264/180 inches. 2.44% of drivers exceeded 30 MPH speed limit

Ordered from narrowest to widest to see how width relates to speed:

  • 224/140 inches. 0% of drivers exceeded 30 MPH speed limit
  • 264/180 inches. 2.44% of drivers exceeded 30 MPH speed limit
  • 252/252 inches. 27.59% of drivers exceeded 30 MPH speed limit
  • 395/395 inches. 53.72% of drivers exceeded 30 MPH speed limit

Notes

Crash data is within 100 feet to avoid the overlap of the final two locations, which were 125 feet apart. Crash data comes from the Illinois Department of Transportation for 2005-2010. The Bushnell Velocity Speed Gun was borrowed for this analysis. The radar gun was filmed to show a speeding car and its speed simultaneously. The video below shows a driver traveling at 50 MPH in a Children’s Safety Zone (as it’s within 1/8 mile of a park, Lincoln Park, making it eligible for automated speed enforcement).

Curiously, no traffic counts have been collected on Clark Street near any of the count locations.

View the video on Vimeo.

Screenshot of traffic count website. Go to the Traffic Count Database System and search for “1700 N Clark Street, Chicago, IL” in the map. 

An enjoyable Friday morning collecting car speeds on Clark Street

Watch this 7 second video of a person driving a late model Toyota Camry in Lincoln Park at 50 MPH, next to the park. 

mean 30.83 mph
median 31
mode 30
min 17
max 50
frequency: 121 cars
greater than 30 mph: 65 cars
% greater than 30 mph: 53.72%

Statistics exclude the three buses counted at 26, 18, 20. Time was 8:23 to 8:38 on Friday, May 4, 2012, at Clark Street and Menomenee Street. The street width at where I collected the data is 65’9″ (789 inches). This location is eligible for a speed camera as it is within 1/8 mile of a park and is thus a “Children’s Safety Zone”.

I’m still working on the report for an article to be published on Grid Chicago. I used this Bushnell Velocity Speed Gun.

3D experimentation to improve pedestrian environment

The movies aren’t the only place where you’ll see in 3D! Go check out Clark and Deming (about 2540 N Clark Street) in the Lincoln Park neighborhood to see a special pedestrian safety marking on the pavement. They were installed on October 18, 2010.

Who’s involved?

  • Chicago Department of Transportation (CDOT)
  • National Highway Traffic Safety Administration (NHTSA)
  • Western Michigan University (WMU)

All three entities are involved in the installation of these optical illusion zig-zag markings.

Between and including years 2005 and 2009, there were at least 2 reports of injuries to people walking and at least 9 reports of collisions involving people riding bikes*. With that data in mind, I’m not sure why this location was selected for a pavement marking whose aim is to improve pedestrian safety. The data do indicate that this intersection has a lot of bicycle-related collisions, much more than I’m seeing for other intersections.

Curiously, there are no automobile traffic counts for miles in either direction on Clark Street so one cannot compare the number of collisions at the Clark and Deming intersection with other intersections in town. Out of over 1,200 count locations, Clark Street in Lincoln Park was skipped.

*Data from the Illinois Department of Transportation Safety Data Mart.

© 2014 Steven Can Plan

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