Smart Cameras Blog

Part 1 of this report considered accident trends in Chicago between 2001 and 2008. Part 2 focuses on accidents at traffic signals. This part focuses on accidents at 39 red light camera (RLC) Intersections based on Illinois Department of Transportation (IDOT) data obtained via the Chicago Tribune. The accident data is publicly available here.

The results show that accidents went UP 5% at the intersections with RLCs. This is a shocking result, because you would expect accidents to decline with the introduction of RLCs. The results also stand counter to the general trend of accidents falling at in Chicago about 7% between 2005 to 2008, as well as the 7% drop of accidents at traffic signals.

Results:

The simplest analysis we did was to look at accidents 1 year prior to the startup date and compare it to accidents 1 year after the start up date for the red light cameras. We found a total of 1118 accidents at the 39 intersections 1 year prior to the startup of the RLC. We compared this to 1 year after the startup date and we found a total of 1192 accidents. So in first year the RLCs were used, accidents as a whole went up at the RLC intersections!

We also used a longer time period, which varied according to the data we have for the individual intersection. The longer time period varied from 347 days to 1080 days with a mean of 500 days. This data also found an increase 4.5% in the number of accidents.

We examined the data to see if there was any “bumps” or changes in red light accidents over time. For example, was there an immediate decrease in accidents and then accidents went back up after 3 months? We found that the rate of accidents was constant at intervals of 1, 3, 6, 9, and 12 months.

Unfortunately, we don’t have access to the entire data set (without manually entering in the Tribune data), so we can’t perform a more sophisticated analysis, such as whether there were changes in the types of accidents (angle & rear end) at RLC intersections.

There are two sources of data on accidents at the RLC intersections. The first is from the Illinois Department of Transportation (IDOT), which is used here. The second is from Chicago’s Department of Transportation (CDOT). Accidents at intersections are measured differently by both agencies. CDOT defines the intersection as extending along the arterial street for a distance of 25 to 50 feet while IDOT will use measurements of 150 to 300 feet. Despite the differences in measurements, we believe any tanglible affect of RLCs should be found at either distance.

The startup dates for the cameras varied from January 1, 2006 to Nov 26, 2007. The analysis compares accidents in the year prior to the installation date to one year after the installation, e.g., for a camera installed on April 1, 2006 the year prior data is from March 31, 2005 to March 31, 2006. The year after is April 1, 2006 to April 1, 2007.

rshah Chicago, Red Light Cameras

Part 1 of this report considered accident trends in Chicago between 2001 and 2008. This part focuses on accidents at traffic signals. The theory behind red light cameras is that people will drive more carefully at intersections. If they are driving more carefully, we should expect accidents to fall across all traffic intersections, not just the ones with red light cameras.

Here are the main points:

1. Accidents at traffic signals are down, but once we account for the general drop in accidents, the accident rate at traffic signals is holding relatively constant. (There is no halo safety effect from the red light cameras on accidents.)

2. There appears to be a steady drop in Angle crashes over the last 5 years, indicating that there is a change in behavior at traffic signals.

First, consider the overall trend in accidents at traffic signals:

A quick look at this graph shows that it is very similar to the overall drop in accidents. To factor out the general trend of accidents dropping, we next determined the percentage of accidents that occur at traffic signals in Chicago between 2001 and 2008.

This graph shows that the percentage of accidents at traffic signals hasn’t changed appreciably between 2001 and 2008. If people were driving more carefully at traffic signals, it would be expected that accidents at traffic signals would become relatively rarer. For example, dropping from a share of 25% of all accidents to 20% of all accidents. The results here suggest that traffic signal accidents are holding relatively constant. This also suggests the RLCs are not having a halo effect because accidents are not dropping throughout the city at traffic signals.

The next step was to consider the types of accidents occurring at traffic signals in Chicago between 2001 and 2008.

The biggest finding here is the drop in Angle crashes (crashes where cars are heading in different directions). Between 2003 and 2008, there is a 5% drop in Angle crashes at traffic signals. This is a large! This drop supports the argument that red light cameras are leading drivers to be more careful at traffic intersections.

For both turning and rear end type crashes, their was little change with the exception of the 2008 numbers. Hopefully, 2009 numbers will identify if there is a trend in an increased share of rear end accidents and a decreased share of turning accidents at traffic signals.

This data was obtained from the Illinois Department of Transportation (IDOT). IDOT has a separate variable for traffic signals in their accident data.  This allows us to isolate accidents that occur at traffic signals.

rshah Chicago, Red Light Cameras

The is the first of a series of posts on report on red light cameras in Chicago.

The two important points:

1. Accidents are down 21% between 2001 and 2008, largely due to people driving less.

2. Any analysis of accidents needs to account for this trend. This trend suggests fewer accidents at construction zones, school zones, highways, and traffic signals (EVERYWHERE). If you are suggesting anything has contributed to safety, e.g., red light cameras, you need a control group to identify the contribution of the safety device or program. Otherwise it will appear that red light cameras have led to a drop of 20% in accidents (when the drop is due to other factors).

Lets begin with a graph of accidents in Chicago between 2001 and 2008:

Clearly there has been a decline in accidents (over 21% between 2001 and 2008). There are a lot of factors affecting accidents from gas prices to the weather. One factor that can be taken into account is how much people drive. The IDOT provides an Annual Vehicle Miles of Travel statistics that allows us to account for how much people drive over a year.

The graphs shows that vehicle miles have dropped in Chicago from 12.6 billion miles in 2002 to 11.6 billion miles in 2008. If people drive fewer miles, it seems reasonable that there will be fewer accidents. We can analyze this by looking at the accident rate for each mile traveled.

This graph shows when we take into account the fewer miles driven in the city, there is no longer a steady drop in accidents. Instead, it’s hard to find a significant trend between 2001 and 2008. It’s also important to note that you can find either a trend of accidents going up, down, or holding steady depending on the what years you include. So once we account for people driving less, there is not a steady trend of accidents dropping.

rshah Chicago, Red Light Cameras

My red light camera study is going public this week, you can see TV coverage over at FOX – New Analysis Shows More Crashes at Intersections With Red Light Cameras.

A longer description can be found at The Expired Meter. I will provide the full report in a few days for everyone.

rshah Chicago, Red Light Cameras

[From Security Info Watch via Crain's Chicago Business]

The Chicago Police Department is pushing for the use of 200 cameras along interstate highways between Chicago and Mexico. The cameras would be fitted with ALPR technology, allowing them to identify suspicious cars. This would become the nation’s largest interstate police camera surveillance system. Specifically, the project would include “192 stationary cameras covering roughly 1,200 miles of highway across 13 states and connected to 50 mobile license plate recognition systems in vehicles.” The data that comes out of this will be immense:

Pictures of license plates and the rear end of vehicles would be time-stamped with GPS coordinates and fed into a computer that would compare them against local or national hot lists of suspect vehicles, with the information shared by participating agencies. In addition, the data would be used to analyze trends and develop patterns of travel by vehicles suspected of trafficking contraband between Chicago and the border of Mexico, according to the proposal.

While the original purpose is to identify trends in vehicles carrying drugs, the data could be used for much more. The eight page proposal can be found online at Scribd.

rshah ALPR, Chicago

[From Chicago's $1.3 Million Experiment in Democracy: Participatory Budgeting in the 49th Ward]

The 49th Ward, home to over 60,000 people and the neighborhood of Rogers Park, is known for its diversity and vibrant community life. Over 80 languages are spoken within less than two square miles. Independent-minded citizens have often put intense pressure on local officials. Concerned that Moore wasn’t responding to ward needs, they nearly voted him out of office in the last election. So how does one of the nation’s most diverse neighborhoods bring opinionated residents together to make difficult budget decisions?

Moore started by setting aside his $1.3 million “menu money,” the discretionary budget that each alderman receives for capital infrastructure projects.

. . .

The Public Safety Committee, for instance, received many requests for security cameras. To learn more, they visited the neighborhood’s 24-hour camera viewing center. As community representative Marilou Kessler explained, “everyone [on the committee] came—about 15-16 people on a workday. It was astonishing cooperation.” The trip shifted the committee’s priorities: They learned that the cameras are used only occasionally, mostly by specialty police teams, and are not continuously monitored. After police explained that lighting is more effective at deterring crime, the committee replaced several camera proposals with street light proposals. (my emphasis)

It appears the CPD thinks that lighting is more effective than cameras!

rshah Chicago

[From New 911 chief wants private-sector cameras to link in :: CHICAGO SUN-TIMES :: City Hall]

The head of the OEMC, Jose Santiago, wants to further expand Chicago’s camera network.

Santiago said there are still parts of the city “where we can’t see.” And private cameras are the quickest, cheapest way to erase those blind spots.

“Here’s a camera that cost the city nothing. We can help our first-responders. . . . We can flip a switch and we’re there already. We can say, ‘This is what you’re about to get into. You might need more resources.’ We can say, ‘Maybe you shouldn’t go in this way,’ ” Santiago told reporters after his City Council confirmation hearing.

According the article, the OEMC used private cameras to track the whereabouts of Michael Scott. It sounds like Santiago wants to use the private cameras, just like the city uses the public cameras, for watching live feeds of crimes taking place and using archival footage for investigations.

The funny thing is that the agreement between the OEMC and the owners of the private cameras is worded very differently. According to the “Memorandum of Understanding”, the OEMC only has permission for real time video in cases of “emergency management” and “disaster” as defined by the Municipal Code of Chicago, Section 2-29-010. Here are the relevant definitions:

“Disaster” means an occurrence or threat of widespread or severe damage, injury, or loss of life or property resulting from any natural or man-made cause, including but not limited to fire, flood, earthquake, wind, storm, hazardous material spills or other water contamination requiring emergency action to avert danger or damage, epidemic, air contamination, blight, extended periods of inclement weather, drought, and critical shortage of fuels and energy.

“Emergency management” means the efforts of the city to develop, plan, analyze, conduct, provide, implement and maintain programs for disaster mitigation, preparation, response and recovery.

The OEMC’s position is publicly available here:

What cameras does OEMC want to access?

OEMC is only interested in obtaining access to exterior cameras on the public way.

How often will the camera feeds be accessed?

Camera feeds will only be accessed during emergency situations and after appropriate notification has been given.

Who will have access to the camera feeds?

Highly trained Crime Surveillance Specialists will have access to the cameras, but again, only during emergency situations.

Will OEMC be recording footage from the cameras?

OEMC will NOT be recording camera feeds.

It’s pretty clear that Santiago’s views are not in accord with the MOU’s the city has entered into and the OEMC’s stated position regarding private cameras.

rshah Chicago

[From Cameras make Chicago most closely watched US city | Latest National Headlines | News fro...]

An AP story on the Chicago cameras provides a broad overview of the issues. A similar story by the WSJ ran a few months back. The story touches on a number of themes that I have discussed on this blog including the scope of the camera network, integration of private cameras, concerns about the effectiveness of cameras, and worry about the potential abuse of the camera system by government.

rshah Chicago, General

[From Spy cams on sweepers brushed aside -- for now :: CHICAGO SUN-TIMES :: City Hall]

The Sun-Times reported last week that the experiment on installing license plate recognition software (ALPR) on street sweepers has stalled. The idea was to use street sweepers to identify illegally parked cars and then generate tickets based on the license plate of the cars. The idea seemed to work in early tests and the project, dubbed “Sweepercam,” earned a 2009 CIO 100 award. While seem people didn’t like this idea, I thought it was a very reasonable way of using smart cameras. The street sweepers go up and down every street, why not let them ticket illegally parked vehicles?

The city tested the cameras on six sweepers. I initially assumed the results were positive, because of the news coverage. However, the city never revealed any details on the tests of sweepercam. I can assume the benefits were not significant, since they are not going forward. The news story gives two reasons for why the program is stalled. The first is that it is to expensive to do:

“To get the desired results consistently, we need to pair our camera technology with higher-tech signage that will work in conjunction with the cameras to confirm our data so that it can stand up in a hearing,” said Streets and Sanitation spokesman Matt Smith. To post those signs citywide would require “time, effort and resources” the city doesn’t have, Smith said.

The other reason comes from the contractor:

John Kosiba, chief operating officer for Span Tech, said the cameras are being removed until the Legislature decides the future of video surveillance for moving violations.

I really don’t understand the reason given by the city. What is higher-tech signage? The only thing I can figure out, is that the city needs a way to prove a car was at a given location. Please let me know if you understand the city’s position.

rshah ALPR, Chicago

[From Ald. Leslie Hairston Wants To Revive Gunshot-Location Technology In Chicago - cbs2chicago.com ]

Fifth Ward Ald. Leslie Hairston wants Chicago to reintroduce the Shotspotter gunshot location technology. After all, Shotspotter’s web site says it can reduce crime. So why isn’t the CPD using it? Don’t they care?

The CPD did adopt Shotspotter and found mixed results in Chicago. Specifically:

The city conducted three separate tests of gunshot sensors between 2003 and 2007 in the West Side’s Harrison Police District. Only on one occasion did the detection system send a warning prior to a person calling 911 to report the shooting. As a result, the city felt the gunshot detection systems were too expensive at a cost of $200,000 a square mile.

The city is going forward with installing the technology in the Loop. However, Shotspotter is an expensive technology and the CPD decided it wasn’t the best use of their scare resources. The city of Chicago is approximately 227 square miles, so to cover the entire city would cost close to $50 million.

The Shotspotter technology locates gunshots. In a dense city, 911 calls often serve the same function. Gunshot location is a useful piece of information for police officers, but it is not a silver bullet. It cannot by itself reduce crime. If the system is reliable and works well with officers, it could lead to less shootings (but not necessarily less crime). The independent studies I have seen show the results are quite mixed.

In Chicago, there has been a rash of shootings in Chicago were no regard for the police or cameras. Shotspotter is now the silver bullet. I am concerned that Shotspotter is seen as the answer because people are scared. It doesn’t make sense to spend money on technology that makes us feel better, but is ineffective. The city can address this by making public its tests of Shotspotter. I would like more details about the tests, for example: How many gunshots were there during the tests? How accurate was the system?

rshah Chicago, Gunshot Detection