Frequently Asked Questions
This page contains answers to FAQs in the following categories.
What are the requirements for viewing this site?
This site can be viewed in Internet Explorer 8 or higher (SWITRS GIS Map requires Internet Explorer 9), Mozilla Firefox 7 or higher, and Google Chrome 8 or higher. For the best viewing experience, Mozilla Firefox or Google Chrome are the recommended browsers. Adobe Flash is required to view the tutorial videos. You should also set your browser to enable pop-ups for this site in order to display all content.
Many portions of the site require using a free account to log-in and access them.
Why did I not receive an account approval email?
Your email server may be blocking the approval email. Please add the firstname.lastname@example.org email address to your safe list and click the Forgot Password link to re-send a new password.
Can I change my password?
No. For security reasons, the password generated is the password you must use. We recommend storing it in your web browser for easy log-in. If you lost your password, click on the Forgot Password link and you will be sent a new one immediately.
How can I make the queries or mapping features faster?
The SWITRS collision, party and victim files contain numerous fields for each and every collision. When querying statewide over multiple years, it takes a considerable amount of work for the server to find all the appropriate crashes. If you subsequently map those results, the performance will also be slower to accommodate so many records. It is recommended to restrict your query based on time or location or collision factors as much as possible, especially for exploration purposes. There are approximately 200,000 fatal or injury records each year in SWITRS, so queries can become large very easily.
How do I query collisions that occur outside of city limits in Unincorporated Areas?
After you select a county in the query tool, the cities list will be populated with all the available cities as well as an UNINCORPORATED entry. Selecting UNINCORPORATED will show the proper results.
Why do I see a different number of collision results for the same query in the SWITRS Query & Map vs the SWITRS GIS Map?
The SWITRS Query & Map includes all collisions regardless of whether they were geocoded or not. The SWITRS GIS Map only uses the data that was geocoded and could be mapped. Therefore, you will usually see a lower number of collisions in the SWITRS GIS Map than the SWITRS Query & Map tools. You can verify which collisions were not mapped in the SWITRS Query & Map tool by clicking on the 'List Unmapped Collisions' button above map on the summary page.
Why do I see fewer collisions in my query than in my SWITRS data in our office?
TIMS contains the fatal and injury collisions, but property damage only collisions are not included. Many agencies have the property damage only collisions in their local datasets, so there will be a greater number of collisions. Not all records were able to be geocoded, either, so you may see fewer collisions in the maps.
Can you give more information about the geocoded coordinates in the SWITRS data files?
Approximately 90 percent of fatal and severe injury collisions have been geocoded through a process developed at SafeTREC. The Point_x and Point_y fields contain the longitude/latitude geocoded coordinate locations based on the 1984 World Geodetic System (WGS84). If the collision was unable to be geocoded, these two fields will remain blank. If you are downloading a subset of data, it will include all collisions that matched your criteria, but if you use the mapping tools only collisions that were geocoded will be displayed. Note that the longitude and latitude coordinates are different from the GPS coordinates that are also provided with some collision records from CHP.
How do I download more collisions than the web mapping applications allow?
You can download the entire set of available SWITRS collisions on the SWITRS Resource page. These are provided in zip files for Shapefile and .csv format. You can then use your own GIS or statistical software to subset and analyze the data.
How do I display downloaded SWITRS datasets in other GIS software or applications?
There are countless software and web applications for displaying data with XY coordinates. Each application will have its own steps, but it should be relatively straightforward. For displaying the data in ArcGIS, the following link shows the exact steps:
Why are there fewer collisions in the most recent year of data available?
SWITRS collision data currently takes about 18 months to be input by CHP. For example, the final dataset for 2011 will not be available until summer 2013. On TIMS, we extract the most recent year of data available from the CHP on a quarterly basis. It will contain whatever records have already been input by CHP before that date. Therefore, until the most recent year is finalized, it will always show fewer collisions in TIMS.
Why do I not see all schools on the maps?
The schools were obtained from the California Public Schools Database. The XY coordinate location of the schools were provided in the database for most records. Some schools without coordinates were geocoded by SafeTREC and other schools were modified for incorrect coordinates. Schools for each city were spatially selected within the city boundaries. If you do not see a school of interest, check the map for the adjacent city or county unincorporated area since the school may have been placed there on the map.