Geocoding collisions at non-existent street network locations

In continuation of our geocoding overview series, today’s post describes the scenario where a collision cannot be geocoded because the location does not exist in the available street network data. The location may not exist for several reasons: The street network is outdated so it does not contain new developments The street network is incorrect and the roads appear in a slightly different location The collision occurs at a driveway, alley or other private entrance that is not a public roadway Typically the last situation is the most detrimental since those locations frequently have the highest number of collisions due to […]

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Geocoding collisions at offset intersections

Today’s blog post tackles the first geocoding issue outlined in our geocoding overview series: how to handle geocoding collisions at offset intersections. In the example below Collins St intersects with Reseda Blvd in two separate locations about 150 feet from each other: Offset intersections can be a common occurrence in some cities or they may just be isolated to several corridors. Regardless of their frequency, they pose a challenge when attempting to geocode collisions and in many cases can leave some level of ambiguity in the location. This is especially true if one does not have access to the original crash report to investigate […]

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City of Los Angeles geocoded SWITRS data free download

UPDATE Geocoded SWITRS data is now provided through the City of Los Angeles Geohub. You can search for SWITRS to find the latest available data at: http://geohub.lacity.org/datasets?q=switrs The data originally linked on this blog post below is no longer updated. ————–   On the heels of releasing the HSIP Helper a few weeks ago, we are now providing a full set of geocoded SWITRS data for the City of Los Angeles to planners, engineers, researchers, or anyone working with collision data in Los Angeles. While many of you have utilized the great service provided through TIMS at UC Berkeley, you may have […]

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Geocoding collision data for RoadSafe GIS

Accurately geocoding collision data is necessary when building a collision database that will be used for spatial analyses. Geocoding is the process of assigning a latitude/longitude (X/Y) coordinate to a descriptive location. For collision data, the descriptive location is typically a primary road and a secondary intersecting road. To geocode a collision the primary and secondary road must match to a location on a digital street network. When the collision location is described perfectly without typos, it is usually easy to match.  However, there are frequently typos, abbreviations or other anomalies that make it difficult to match the collision to a street network. In addition, […]

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Announcing the HSIP Helper

We are happy to introduce the HSIP Helper at www.HSIPhelper.com for agencies to explore systemic countermeasures for their California HSIP Cycle 7 applications. For more background information, please see our previous post. The intent of the HSIP Helper is to illuminate the high benefits of systemic countermeasures and to help those agencies exploring their data to identify potential countermeasures that they may not have previously considered for their HSIP application. If your agency already has picked out their projects, this tool will not be beneficial. Before we dig into any more details, it is important to note that this tool is […]

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California HSIP Cycle 7

UPDATE: See Cycle 8 blog post for the latest information. Caltrans has announced plans for $150 million to be distributed during the Highway Safety Improvement Program (HSIP) call for projects. The goal of the federally mandated HSIP is to: Achieve a significant reduction in traffic fatalities and serious injuries on all public roads, including non-State-owned public roads and roads on tribal lands. The state departments of transportation are tasked with maximizing the benefits of their designated funding through a data-driven approach. The Caltrans Division of Local Assistance manages the California HSIP program and has established a protocol of evaluating applications based on a […]

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Collisions vs Injuries

Evaluations of collision data inevitably require summarizing the number of collisions or injuries occurring on a roadway or region. Target safety goals, baseline analyses of conditions and comparative rankings are all based on counts. However, when reviewing the numbers it’s important to make sure you are comparing apples to apples and not apples to oranges — aka collisions to injuries (or fatalities). During my time at UC Berkeley’s SafeTREC, this collisions vs injuries issue frequently presented itself and caused confusion during conversations or when preparing numbers for various reports and presentations. To dig deeper, let’s continue with the pedestrian collision […]

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Querying for pedestrian related collisions

Collision data is inherently complicated since it attempts to aggregate all the elements of a collision into a nice, standardized database. The breadth of information available contributes to the complexity and can make it quite daunting for someone to understand without extensive experience working with the data. I wanted to address some of the more common questions that I have heard over the years and hopefully provide sufficient explanations in a series of blog posts. Given the interest in the built environment and the focus on improving conditions for pedestrians, a common data question is: How many pedestrian collisions were […]

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Collision data GPS coordinate accuracy

The usefulness of RoadSafe GIS or any other software solution is heavily dependent on the quality of the input data. For collision data, the location information is particularly important and in recent years police officers have begun including Global Positioning System (GPS) coordinates in collision reports. Hypothetically using a GPS coordinate would be a better solution than geocoding collision data based on the intersection name, but the reality is that GPS coordinates may not be quite ready for prime time. One of my last tasks at UC Berkeley was to finish an evaluation of the GPS coordinate accuracy for California […]

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About RoadSafe GIS

RoadSafe GIS is the fruition of many years working in the field and learning about the needs of local agencies when it comes to collision data. In my previous post, I briefly outlined its origins while working at UC Berkeley and developing the Transportation Injury Mapping System (TIMS). Now I would like to describe current options available to local agencies and how RoadSafe GIS can fill a void as a new software service. Despite the popularity of TIMS, most local agencies in California still maintain their own data in private software solutions. Although TIMS is a powerful, freely available web-based […]

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