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Yesterday, I was travelling West bound on I76/I70 near mile post 118.4 in Pennsylvania. Traffic stopped and after a while my phone got a message, to register at 511paconnect.com (cool this is new and helpful!)

Google maps was showing a travel delay of about 50 Minutes (it varied a few minutes over time). In reality we sat in the same place for 3 hours.

511PAConnect is a new, trapped-traveler emergency communications tool that allows incident response teams to communicate via automated phone or text message directly with motorists who are trapped in a roadway backup. The tool also gives emergency crews a clearer picture of who is sitting in a trapped vehicle and where they are, so agencies can better plan for the use of resources. Source

So I registered and went to the site for details. I received a message an hour plus later, on the phone and the web page showed that the accident (7 miles ahead) was cleared and traffic was starting to move.

Google maps showed the travel delay clearing, and for a long time while we were sitting there, it showed, the road was clear with no delays.

BUT it was another HOUR before the car in front of me moved at all. I mean really not moving. Once we started moving we travelled at 20 to 40 MPH until passing the accident (truck jackknifed) site, and to the next exit (where I got off)

Why did 511paconnect.com tell me we would be moving soon (implying minutes) when really it was still an hour delay?

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closed as primarily opinion-based by Giorgio, Mark Mayo♦ Mar 21 '18 at 23:27

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • The PA in the domain name suggests Pennsylvania, but it would be better to be explicit. "Milepost 118.4" could be in Ohio, Indiana, Illinois, …, Colorado, Wyoming, Nevada. – WGroleau Mar 22 '18 at 3:06
  • @WGroleau updated. – James Jenkins Mar 22 '18 at 16:54
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Because there was seven miles of backed up traffic between you and the accident. Once the accident was cleared, you had to wait for that to get out of the way.

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A lie is an intentional misstatement, meant to mislead you. So I don't think they lied to you. They may have underestimated the time for the traffic backlog to clear, which wouldn't be surprising, given the complexities of traffic situations. There are countless variables that could have affected how long it took to clear traffic - bearing in mind that there are degrees of traffic being clear. If all lanes are shut down, and they get one lane open, traffic at least can start moving again, but it may still take a long time for the backlog to clear.

It sounds to me like this service's primary intention is to help find people who might need rescuing, not to estimate traffic times, and the traffic time estimate is a bonus that perhaps needs some refining. But even the most refined exception estimates are going to be difficult to make.

We got affected a few years ago by mudslides on the Trans-Canada Highway near Golden, British Columbia. The estimates there were quite informative: they gave a time estimate, and then a confidence estimate. In that case, they were expecting an eight-hour closure with low confidence, which meant that they could clear the existing mudslide in about eight hours, but did not have high confidence that more slides wouldn't occur. That was enough for us to divert our route south to BC Highway 3, even though it added about four hours to our route.

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Let's look at the numbers. There is a stationary line and you are 7 miles from the incident. Suppose each car takes 10 yards of road (I presume you are in America). That is 176 cars per mile, so about 1200 cars are waiting in each lane.

When the road is cleared, if each vehicle starts moving at 3 second intervals, you will start moving after about 3600 seconds: one hour.

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  • If it took 3 seconds for a car to start moving, only 20 vehicles per lane would make it through a stop light that was green for a minute. I looked for solid numbers and could not find them, but based on experience I think the average is probably closer to 1 second per vehicle. Traffic should have been moving in at least 20 minutes 7 miles away. – James Jenkins Mar 22 '18 at 16:50
  • @JamesJenkins why "should" the traffic have been moving in 20 minutes? It wasn't. My 3 seconds estimate is based on obsersvation of how a typical line of traffic gets moving. It was just a rough estimate. In my town a 30-second traffic light will let through about dozen cars. – Weather Vane Mar 22 '18 at 18:44

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