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[aprssig] Symbols for traffic alerts

Steve AB3LT at roseandsteve.us
Fri Nov 11 20:14:14 UTC 2011


Morten,

Here are the symbols I use for objects in my area:

"BUILDING FIRE" "/:"
"DEBRIS/FLUIDS ON HIGHWAY" "/P"
"DISABLED VEHICLE BLOCKING" "/P"
"DISABLED VEHICLE" "/P"
"ELECTROCUTION" "EJ"
"HAZARDOUS ROAD CONDITIONS" "Hj"
"PLANE CRASH" "A'"
"ROAD OBSTRUCTION" "Oj"
"S/B AT HELICOPTER LANDING" "/X"
"TRAIN CRASH" "T'"
"VEHICLE ACCIDENT FIRE POLICE" "F'"
"VEHICLE ACCIDENT INJURIES" "I'"
"VEHICLE ACCIDENT MOTORCYCLE" "M'"
"VEHICLE ACCIDENT PEDESTRIAN STRUCK" "P'"
"VEHICLE ACCIDENT RESCUE" "R'"
"VEHICLE ACCIDENT STAND-BY" "S'"
"VEHICLE ACCIDENT UNKNOWN INJURIES" "U'"
"VEHICLE ACCIDENT" "\'"
"VEHICLE FIRE" "/:"
"WOODS/FIELD FIRE" "/:"

any other EMS "/a"
any other Fire "/f"
any other Traffic "/P"

The Objects have a object id in the format "EMS XXXX", "FIRE XXXX", or
"TFX XXXXX"  where XXXX is the base36 encoded incident number. I
uppercase and use the incident type and subtype as the object comment
text. If the incident is along a major roadway  (state route, highway,
turnpike) I add an abbreviated version of the road followed by either
a single pipe | if the incident affects only one lane/direction,
double pipe || otherwise denotes that both lanes/directions are
affected.

I have a self adjusting net cycle time which retransmits still active
incidents about every 20 minutes. this self-adjusts if there are a lot
of incidents like during a blizzard, but it stays mostly at 20 minutes
the rest of the time.

I send these objects out with a path including  RFONLY,NOGATE and tag
them with the !x! no-archive flag because I reckon that if someone has
an internet connection to receive APRS-IS then they also have an
internet connection to traffic.com or any of the other sources for
traffic/incident information, and they don't need to get this from the
aprs-is backbone, unlike most stations on RF.

When sending object kill messages I replace the last part of the
object comment text with (CLEARED) so that text-only displays like the
hamhud and D700 users can see that the incident has ended.

I populate the Object's timestamp with the dispatch time of the
incident, comparing it to when you received the object you can
calculate how long the incident has been active.

here's an example:

AB3LT-1>APZS13,WIDE2-2,EPA2-2,RFONLY,NOGATE:;TFX
6USLF*021347z4001.50NI07513.70W'I76 || VEHICLE ACCIDENT INJURIES
 !x!

AB3LT-1>APZS13,WIDE2-2,EPA2-2,RFONLY,NOGATE:;TFX
6USLF_021347z4001.50NI07513.70W'I76 || VEHICLE ACCIDENT
INJURIE(CLEARED)!x!


hope this helps and 73,
Steve AB3LT

On Fri, Nov 11, 2011 at 3:43 AM, Morten Johansen <morten at bzzt.no> wrote:
> Hi, list!
>
> I've been following the list for a while, but this is my first post. I hope this is the right place to post this question.
>
> The Norwegian Road Authorities are kind enough to post traffic alerts in XML format including geographic position, urgency information and other "snacks".
> For some months now I've run an experiment that analyzes these alerts for my area and injects them into the APRS-IS as objects.
>
> There has been lots of feedback, and all interested parties (including NRRL) have been rounded up in a mailing list to try to outline a permanent service.
>
> Alerts have a "type", of which the most common are: "closed road", "temporarily closed road" or "reduced navigability road". It basically describes the impact of the alert for traffic.
>
> The majority of the alerts come from road work, and because of this the \j Work Zone symbol is used by default.
>
> Our question to this list is what APRS symbols we should use for these situations:
>
> * Closed road
> * Traffic incident - \' ? We have no way of knowing if it's a car, truck or whether there are several involved. Looking for a general traffic incident symbol.
>
> We also would like some opinions on which symbol should have precedent in case of "closed road" because of "traffic incident".
>
> Should the "closed road" symbol be used always for consistency?
> Should the "traffic incident" symbol be used to provide information granularity?
> The object text will contain a short description of the situation in any case.
>
> de Morten LA1FTA
>
>
>
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