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Using CHP Traffic

CHP Traffic uses information published by the California Highway Patrol, so it helps to understand how this information is structured. The CHP divides the state of California into a number of districts or dispatch centers. Each CHP dispatch center is divided into a number of reporting regions, generally centered around a CHP office. Traffic incidents are associated with reporting regions.

The CHP Traffic interface is divided into six primary tabs: Favorites, Nearby, Browse, Map, Glossary, and Settings. The use of each tab is described in more detail below.


Favorites Tab and Common Features

The Favorites tab gives you quick access to the CHP reporting regions you choose. All incidents reported in that region are shown in a summary view, highlighting the type of incident and its location. To find out more information about any incident, simply tap it, and a detailed view will appear as shown at left. The detail view shows additional information such as when the incident first came to the attention of the CHP, and the full CHP log. As the CHP logs generally use abbreviations, you will likely want to refer to the Glossary tab or turn on Expand Terms in the Setting tab to automatically expand abbreviations.

Features common to Favorites, Nearby and Browse tabs:

All traffic incident displays (Favorites, Nearby and Browse tabs) have a search and filter interface at the very top of the display. By default, this display is usually hidden just above the top of the incident listings to stay out of your way, though it will come into view if there is enough room on the screen. To expose it if it is hidden, simply scroll to the very top.

Press and hold an incident listing to share it with other people. You can send either a link (that other CHP Traffic users can open) or the full incident details by SMS text message or e-mail. You can also copy the detailed incident log into the clipboard, allowing you to paste the details into another application, or tweet about the incident via Twitter (new in 3.0).

In an incident detail screen, when an incident's approximate location is known, the GPS coordinates will be shown as the location of the incident. Press and hold these coordinates and you will be asked if you would like to see the incident on the built-in map tab, or in the Apple Maps application. An easier way to view the incident on the map tab is to press the blue disclosure chevron to the right of the coordinates.

New in 3.0: If you have a Twitter account configured and Twitter feeds are enabled in CHP Traffic's Settings, a Twitter feed showing recent public tweets about the incident will be displayed. Refresh the feed using the refresh button as desired. You can tweet about the incident (press the Twitter bird icon) or tweet a photo (press the camera icon).

Nearby Tab

The Nearby tab uses the GPS in your iPhone to find which CHP regions are nearest to you, and show you the traffic incidents filed in those regions. CHP Traffic does not share your current position with the CHP or any other entity. Note that the first few times you use the Nearby tab, you will be asked whether you would like to give CHP Traffic access to your current position. Your iPhone will eventually learn your choice and stop asking. The Nearby tab is particularly well-suited to using the Route Filter system described below.

The Nearby tab shares features with the Favorites tab; see above.

Browse Tab 

The Browse tab allows you to look at all incidents in any CHP dispatch center. Incidents will be organized by reporting region within the dispatch center. As with the Favorites and Nearby tabs, simply tap an incident to view detailed information.

The Browse tab shares features with the Favorites tab; see above.

 Map Tab

The Map tab lets you see incidents for which the approximate location is known on a map as map pins. The Map tab can track your position, continuously scrolling the map to keep your location centered. This is enabled and disabled with the location icon (a directional arrow as in the Apple Maps application) in the right hand side of the tool bar. You can zoom in on the map by pinching open or by double tapping;  you can zoom out by pinching or by using two fingers to tap. Clicking on a pin will reveal summary information about that incident. The magnifying glass icon will zoom in on that incident; the disclosure chevron will display detailed information about the incident in the Browse tab.

Note that incidents for which location information is not provided will not be shown on the map. The info button in the toolbar will give you information on how many incidents are being displayed.

Glossary Tab

The Glossary tab provides the official CHP glossary of abbreviations and numeric codes. Use the index on the right side of the table to jump to a specific section quickly. Alternatively, you can search for terms by scrolling the display to the very top above the section A to reveal the search bar.

 Settings Tab

The Settings tab allows you to customize some aspects of the application. You can currently control the following:
  • Automatic Refresh Interval: the interval at which the program fetches updates from the CHP
  • Animated Updates: Update incident or detail listings with animation to make it more obvious what is changing. If you experience crashes during updates, you can turn this off, but please let us know that you are having trouble!
  • Prevent Device Sleep: prevent the device from automatically locking; this uses more battery power, but keeps the screen from going to sleep
  • Decimal GPS Values: Controls whether GPS values are in degrees, minutes, and seconds, or simply decimal degrees.
  • Report Diagnostics: CHP Traffic saves diagnostic information when it encounters certain problems. When this setting is on, CHP Traffic will offer to send this information to us (you can still say no). When off, the information will not be sent.
  • Expand Terms: automatically expand glossary terms found in CHP log details
  • Highlighting: You can customize which incidents are shown in red.
  • Search Range: sets the distance (from your current location) that is searched for nearby CHP reporting regions; incidents in the "nearby" reporting regions appear on the Nearby tab.
  • Twitter Feeds: (iOS 5.0 only) When on, CHP Traffic will display public tweets about an incident.
  • Twitter Cache Size: (iOS 5.0 only) Controls how many days Twitter user information will be cached on the device. Caching is necessary because the number of requests Twitter will allow from a device is limited. However, note that iOS 5.0 itself will automatically purge this cache if space is low on the device.

Route Filters

An advanced feature of CHP Traffic is the ability to apply a saved filter in any incident listing. A saved filter consists of a set of freeways that you specify, including an optional direction specification. When applied to a listing of CHP incidents (for example, the listing in the Nearby tab), only incidents that match one of the freeways that is part of the route filter will be displayed. For example, a route filter might be comprised of Eastbound CA-134 and Interstate 210. In this case, only incidents on Eastbound CA-134 and incidents in any direction on Interstate 210 will be displayed. Incidents that don't specify which direction of CA-134 they affect would also be displayed. Conversely, incidents on US-101 or Westbound CA-134 will NOT be displayed.  Note that, unlike a simple search, an incident described as "US101 JNO SR134" would not be displayed by this example route filter because this incident is ON the US101, and not CA-134. 

Route filters can be applied in any incident listing, including those in the Favorites, Nearby, and Browse tabs.  However, they are most useful with the Nearby tab.  Suppose you are making a long road trip from Santa Barbara to northern California. You're planned route might be: US101 to CA-46 to CA-41 to I-5 to CA-99. You could set a route filter to consist of each of those freeways and apply it in the Nearby tab. As you made your trip, only inicidents on those freeways that were nearby would be listed. So, while you were still in Santa Barbara, you would not see incidents listed for US101 in the San Francisco Bay Area, nor would you see incidents for CA-154 in the Santa Barbara area because CA-154 was not part of the route filter.

Defining a Route Filter

Defining a route filter is simple. When you select the Route Filter button beneath the search bar, and click the bookmark button, you are taken to the Filter Manager screen where you can manage your route filters. To add a new route filter, click the Edit button. You will be taken to a new screen where you can name the new filter. To add routes to the filter, click the Add (+) button. If this is not visible, you may need to press the Edit button. On the next screen, you can choose an individual route. This generally involves entering the highway number into the text box, and choosing the type of freeway (CA state route, Interstate, or US highway). You can optionally specify a direction.

Using a Route Filter

To apply a route filter, scroll to the top of any incident listing, and tap in the search bar. That will disclose two buttons underneath the search bar: "Route Filter" and "Search." Tap the Route Filter button, and then tap the bookmark button to bring up the Filter Manager display. From there, simply tap on the filter you wish to apply. You'll be returned to the incident listing, and the name of the filter will be shown in the search bar. To stop filtering, tap the Cancel button to the right of the search bar.


Searching vs. Filtering

Route filters are different than the simple search that is available when the "Search" button beneath the search bar is selected. With route filters, CHP Traffic attempts to parse the CHP's description of where the incident is located into freeway/street names. Using that information, only incidents with matching freeways in the route filter will be displayed. By contrast, the simple search mechanism will find any incidents whose location or description contain the text typed into the search bar. For example, if you enter "101" in the search bar, you will see incidents that occurred on the US101 (as with a route filter), as well as incidents that reference 101 such as "SR134 JEO US101" and "35101 MONTEREY ST."

Editing a Route Filter

Editing a route filter is similar to defining a new one. From the Filter Manager screen, you can edit an existing filter by clicking the disclosure button at the right hand side of the entry you wish to edit. To delete a filter that is no longer used, click Edit and then press the delete button at the left hand side of the entry. Alternatively, you can simply swipe across the row to delete it as in other iPhone applications.

Advanced Usage

In addition to using the bookmark button to apply a route filter from the Filter Manager screen, you can quickly apply a route filter by typing its name into the search bar when the "Route Filter" button is selected. As you type, CHP Traffic will autocomplete to either a unique filter name or the longest common prefix of a number of filters. For example, if you have filters named "Commute To Work" and "Commute To Home" typing the letter "C" will cause CHP Traffic to autocomplete to "Commute To " at which point typing either "W" or "H" will result in CHP Traffic applying the filter "Commute To Work" or "Commute To Home" respectively.