Updated 2026-10-09

What it is and who sends it

A Traveler Information Message carries advisory and regulatory information from the roadside to drivers: "road construction ahead, reduced to one lane", a speed limit sign, an exit services notice, a weather warning. It is a roadside message, created by an agency (often from its advanced traffic management system or a work-zone data feed) and broadcast by an RSU; vehicles show it to the driver when they are inside the region the message names and traveling in the direction it names. The type is TravelerInformation, DSRCmsgID 31. For work zones specifically, the newer Road Safety Message of SAE J2945/4 is a structured alternative; the comparison is in that article.

When it is broadcast

Structure, section by section

Top level: TravelerInformation

TravelerDataFrame

The mutcdCode (regulatory, warning, maintenance, motoristService, guide, rec) tells the vehicle which sign family to render; the viewAngle says which approach headings can see the sign.

GeographicalPath (a region)

A path region is the same node-offset chain used by MAP: the first node is relative to the anchor, the rest relative to the previous node, node-XY1 … node-XY6 chosen by range. The template uses node-XY6 with 95 m steps. A circle region (geometry with a circle of center and radius in the chosen units) is the simplest way to cover an area such as an exit ramp.

Content and ITIS codes

Every item is {"item": {"itis": code}} or {"item": {"text": "…"}} (16 characters maximum per text item). Codes come from SAE J2540-2; the units cheat sheet lists the blocks. The ones most TIMs use:

A speed limit is content type speedLimit with the sequence 268 (speed-limit), 12544 + value (for 45 mph, 12589) and a text item for the unit, which the template writes as MPH. Pair it with frameType roadSignage and mutcdCode regulatory so vehicles render a regulatory sign rather than a text advisory. The creator shows the phrase next to each code as you type.

How to create one in this portal

1. Map builder. Open the map builder, choose TIM, click the anchor, draw the path along the affected direction (or draw a circle), set the heading slices, pick the content type and codes, set start time, duration and priority, and encode. The builder fills the doNotUse fields and chooses node encodings.
2. Creator. Load TIM – Work Zone Advisory (westbound Leesburg Pike near Tysons, VA, three ITIS codes and a text item, 12 hours) or TIM – Speed Limit Sign (45 mph, 32000 minutes, regulatory). Change the anchor and nodes, the direction bits, the content, startTime and durationTime. Set startYear to the current year.
3. Encode / Validate. The hex begins 001F (messageId 31). The map tab draws the path with its corridor width and the sign position.
4. Push to my RSU with PSID 0x8003, a 1,000 ms interval, and a delivery window equal to the TIM's validity. The NTCIP 1218 push guide explains the delivery start and stop fields.

For an agency feed, generate TIMs from your work-zone or incident system through the API and push them on a schedule; see TMC and ATMS integration.

How vehicles show it

An OBU keeps every valid TIM it hears, checks whether the vehicle is inside one of the regions and heading within direction, then shows the highest-priority applicable frame. Regulatory signs (roadSignage) are usually shown as an icon; advisories as text or a spoken phrase; work-zone content may trigger a speed advisory. Vehicles differ in how much text they display, which is why codes are preferred over free text, and why a region drawn too wide, or a direction with all bits set, will show the message to traffic it does not concern.

How to read a decoded one

• Validity. startTime + durationTime must cover now; an expired TIM in an RSU store is a common sight.
• Region sanity. On the map, the path should follow the road in the direction direction names. A path that runs the wrong way with directionality forward applies to nobody.
• direction bits. Westbound is bits 11 and 12; a slice of 1111111111111111 applies to all headings.
• Content. Codes outside J2540-2 decode as numbers with no phrase; text over 16 characters fails to encode.
• doNotUse fields. Must be present and 0; some 2016-era messages carried nonzero SSP indices there and still decode.
• Priority. Several TIMs at the same spot are ranked by priority; a stale high-priority message hides a fresh low-priority one.

Related standards and further reading

• SAE J2735_202409, TravelerInformation module; SAE J2540-2 ITIS phrase list; USDOT's TIM creator tooling and the ODE TIM format; FHWA Work Zone Data Exchange (WZDx) as the source feed most agencies convert from.
• RSM for structured work zones, MAP for the node-offset rules, units cheat sheet, capturing messages.