The Town of Centreville has been collecting speed data utilizing our mobile radar trailer for about a year and a half now. In a previous post, I included the results charts from the various locations around town.
Additionally, we have been working with the State Highway Administration (SHA) to reduce the speed limit on Rt. 213 in town. We were successful in working with them to reduce the speed limit to 25 MPH earlier this spring (see posting here).
On Rt. 213 in town (Liberty St. & Commerce St), the Police have now begun to collect speed data in similar locations as last year. The results are positive. Speeds on these roads are trending downward, but we still have more to do. The good news is that by having SHA reduce the speed limit to 25 MPH, they have given our officers the ability to enforce traffic driving through town at unsafe speeds. Click on any of the graphs below for a larger pdf version.
The 85th Percentile:
The 85th percentile speed is the speed at or below which 85 percent of the motorists drive on a given road when unaffected by slower traffic or poor weather. This speed indicates the speed that most motorists on that road consider safe and reasonable under ideal conditions. It is a good guideline for the appropriate speed limit for that road. (From Maryland State Highway Administration)
The Results:
First: Liberty Street at Ridgeview
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| Liberty Street Speed Data 2010 & 2011 |
The purple lines represent April 2010, when the speed limit was 35 MPH, and the light blue represents July 2011, with the updated 25 MPH speed limit. There are now a much higher percentage of cars going less than 30 MPH than last year.
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| 85th Percentile Speed Comparison 2010 & 2011: Liberty St at Ridgeview |
Here we see that in April 2010, the 85th percentile speed was 33 MPH. It is now at 31 MPH. While only 2 MPH isn't much, it is trending in the right direction. With continued enforcement, we hope to get the 85th percentile to 25 MPH.
Second: Commerce St. at Academy/Turpins
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| Commerce St Speed Data 2010 & 2011 |
The purple lines represent April 2010, when the speed limit was 35 MPH, and the light blue represents July 2011, with the updated 25 MPH speed limit. The difference is amazing. The speeds percentages have almost flipped with a much higher percentage of cars going less than 30 MPH.
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| 85th Percentile Speed Comparison 2010 & 2011: Commerce at Academy/Turpins |
Here the results of the speed modification are much greater. In April 2010, the 85th percentile speed was 31 MPH. It is now at 26 MPH. With continued enforcement, we hope to get the 85th percentile down even lower.
Remember, this is not a perfect scientific study, but it is a good measurement of change over time.
As we have additional results, I will continue to update this blog.
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