SWITRS GIS Map

Overview

The SWITRS GIS Map provides a map-centric workflow for filtering and visualizing California crash data. Open it from the Analysis & Visualizations menu under SWITRS GIS Map. This guide walks through the interface, query options, and supplemental analysis tools.

Browser compatibility

For the best experience, use a modern browser such as Microsoft Edge, Google Chrome, or Mozilla Firefox. Older browsers may not support vector basemaps or advanced rendering options.

Understand the interface

1. Toolbar: Access Map SWITRS filters, analysis tools, layer controls, basemaps, and the location search bar along the top edge.
2. Navigation toolbar: Zoom controls in the upper-left corner help you move around the map quickly.
3. Map: The primary canvas displays crash symbols and optional reference layers. Collapse other panels to create more space.
4. Results panel: Hovering over the map in the upper-right, this panel summarizes crash counts and exposes actions such as exporting data or building crash diagrams.

Map SWITRS toolbar

The Map SWITRS panel drives crash selection by combining temporal, geographic, and attribute filters.

Date and location parameters

Choose a date range (up to the ten most recent available years) using calendar pickers or by typing values. Depending on the selected geography, you can filter by city, county, state route, tribal area, public school, or ZIP code. Tribal areas and schools support optional buffers ranging from 0.25 to 5 miles.

County and City or State Route

To filter by county, select a county from the dropdown menu. For city or state route filtering, first choose a county, then select the appropriate option.

Limit results to crashes on designated state routes by choosing State Highway and optionally selecting a route number and direction. Choose None to review only non-state-highway crashes.

Tribal area

Browse and choose tribal areas within California. Use the buffer options to include crashes within a specified distance from the tribal area boundary.

Public schools

Select a county, then browse and choose public schools in California. Use the buffer options to include crashes within a specified distance from the school boundary.

ZIP code

Select a county, then browse and choose five-digit ZIP codes. Boundaries are sourced from Esri demographics (data details).

Custom area

Select Custom Area to define a specific region on the map using existing boundaries from a GeoJSON or Shapefile. This option allows you to map crashes within your own defined area.

Crash, party, victim, and infrastructure filters

Combine multiple filters, for example, pedestrians aged 65+ by selecting Pedestrian Crash > Yes and Victim Age > 65 to 125. Active filters appear as pills that can be removed with the x button. Infrastructure options currently include Functional Classification; learn more on the SWITRS help page.

Use the SWITRS codebook and Working with the relational database structure resource to understand field definitions.

Identify crashes on map

After selecting appropriate filters, Show Result button in the Map SWITRS panel will display crashes on the map.

Click individual symbols to open identification pop-ups with summary details.

Select Details for a printable one-page summary with Google Street View, or choose Fix Location to report location corrections if you believe the crash location is inaccurate.

Analysis tools & downloads

Beyond Map SWITRS, the toolbar offers additional exploratory and export features.

Spatially select crashes

Select crashes by drawing points, lines, rectangles, polygons, or freehand shapes. Holding the mouse button allows you to create buffers or multisegment selections.

Select by buffer

Buffer tools measure distance-based selections, such as crashes within 25 feet of a corridor or 75 feet of multiple intersections.

1. Enter a buffer distance.
2. Pick a shape type (hover to read descriptions).
3. Follow the map instructions to complete the selection.

Create crash diagrams

After selecting crashes, choose Create Crash Diagram from the Results panel to open the Crash Diagram tool. See the dedicated Crash Diagram guide for details.

Download crashes

Choose whether to export All Mapped Crashes or only Selected Crashes, then pick crash, party, or victim tables. Remember that SWITRS is hierarchical: party and victim filters further narrow the crash set. Review the relational database overview for guidance.

Rank by intersection

Specify a buffer distance, then view the top ten intersections ranked by crash count. Click a result to zoom to its location. Rankings include only crashes matching your filters and intersections designated as primary or secondary roads (A2/A3 Census Feature Class Codes).

Crash summary

Open Crash Summary to view totals and charts for overall crashes, victims, and pedestrian crashes. Use the export icons to download tables or charts.

Print, location search, and side menu

Use Print to generate a PDF with your current map extent and filters. Enter intersections or addresses in the Location Search bar to zoom, and open the side menu for quick access to the same toolbar options.

Navigation controls

Pan by dragging the map, or use the scroll wheel and zoom buttons to change scale. Navigation options include:

• Zoom in and Zoom out
• Zoom to full extent (world view)
• Zoom to current location (if location access is granted)

Map display & layers

Display options

Select Options to switch between point and cluster symbology, adjust sizes, and color-code crashes by severity, type, or vehicle involvement.

Layers

Activate reference layers such as the California Road System (CRS) to display functional classifications. CRS data is unofficial; verify with Caltrans for the most up-to-date information (Caltrans functional classification).

Basemaps

Choose from Esri basemaps such as Streets, Satellite, Light Gray, and more. Vector basemaps offer better performance on newer hardware, but can be disabled if necessary.

Available basemaps

Basemap	Name	Description	Vector option
	Streets (default)	Street-level detail including roads, water features, and key points of interest.	Yes
	Satellite	High-resolution imagery without labels.	No
	Hybrid	Imagery with road and place labels.	No
	National Geographic	Cartographic map featuring administrative boundaries, landmarks, and terrain.	No
	Topographic	Detailed topographic map with political and natural features.	Yes
	Light Gray	Minimal labels and muted colors to highlight overlays.	Yes
	Dark Gray	Dark backdrop emphasizing symbol contrast.	Yes
	OpenStreetMap	Community-maintained street data; often very current.	No
	Streets Night	Night-themed vector street map (defaults to Dark Gray if vectors are disabled).	Yes
	Streets Relief	Streets with shaded relief highlighting terrain.	Yes
	Streets Navigation	Navigation-focused style optimized for mobile devices.	Yes

Results window

The panel confirms how many crashes are displayed and alerts you when the 5,000-crash display limit is reached. Use the actions inside to download data, create diagrams, or refine selections.

Frequently asked questions

How can I make queries load faster?

Limit the query by timeframe, location, and filters to reduce the number of records processed. County-wide, multi-year queries can include hundreds of thousands of crashes and take longer to load.

Why do counts differ between SWITRS Query & Map and SWITRS GIS Map?

SWITRS Query & Map includes all crashes, even when they are not geocoded. SWITRS GIS Map only displays geocoded crashes, so totals are typically lower. Use List Unmapped Crashes in the Query & Map tool to identify missing locations.

Why are there fewer crashes than in our local crash database, i.e., Crossroads?

TIMS excludes property-damage-only crashes, focusing on fatal and injury crashes. Some records may also lack geocodes, resulting in fewer mapped crashes.

How do I find out what SWITRS fields and their values mean?

The format of SWITRS data and descriptions of each of the data fields and their range of values are described in the SWITRS Codebook page.

Can you give more information about the geocoded coordinates in the SWITRS data files?

Approximately 97 percent of fatal and injury crashes 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 crash was unable to be geocoded, these two fields will remain blank. If you are downloading a subset of data, it will include all crashes that matched your criteria, but if you use the mapping tools only crashes that were geocoded will be displayed. Note that these geocoded coordinate locations are different from the GPS coordinates that are also provided by SWITRS which are available by LATITUDE and LONGITUDE fields.

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. Here is the Add XY data help article for displaying data in ArcGIS.

Why are there fewer crashes in the most recent year of data available?

It currently takes about 12-18 months for the California Highway Patrol (CHP) to finalize SWITRS crash data. For example, the final dataset for 2024 will likely not be available until summer 2026. 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 likely show fewer crashes in TIMS.