Travel Time signs

[OCGuy81]

A lot of metro areas have variable message signs that show the travel time to major intersections along the route.

What do they use to calculate the times?  Does anyone know?

[DaBigE]

Most places I know use a basic time calculation between traffic sensors, either side-firing pole-mounted sensors or embedded loops.

[cl94]

Depends. NYSDOT and NYSTA use a combination of E-ZPass readers mounted above the roadway and pairs of induction loops. The E-ZPass readers measure travel times between two points, while the induction loops are two closely-spaced sensors that measure speed, deriving travel time from the speed. The E-ZPass readers are quite common in the northeast, where a significant amount of vehicles have transponders, as they are easier to install.

[Mergingtraffic]

I've noticed in CT they are conservative with the time speed. It'll say:

TO US-7
8 MILES
10 MINUTES

or

TO I-91
12 MILES
15 MINUTES

With both of these examples, traffic was fine and the speed limit is 55mph or lower.  It seems they use google maps or something. If you drive at 60mph, it should be the same 12 miles, 12 minutes.  When I drive it at 65mph its a lot less than what the signs say. OR it seems they are being PC meaning if you go the speed limit that's how long it should take you.

However, I've seen the NJ Tpke do it more realistically.
TO I-276
43 MILES
42 MINUTES

[cbeach40]

MTO uses induction loops for sections with ATMS in place (mostly the GTA) where real time flow is able to be calculated and updated rapidly. For longer distance sections (and most of the legacy Pan Am signage), Bluetooth readers measure the actual flow of unique devices (and therefore vehicles) for those sections.

[ET21]

I believe it's traffic sensors that average the speed of passing cars, then gives you a time over a certain stretch based on combining all the averages in the corridor and averaging that large number.

Travel Midwest uses this to give out its interstate times for Chicago and most of the Great Lakes
http://www.travelmidwest.com/lmiga/home.jsp

[hotdogPi]

I believe I saw this once:

6 MILES
4 MIN

Also, did anyone read the title as "Time Travel signs"?

[noelbotevera]

I-270 NB in Frederick MD has an accurate VMS. I saw it on at night. It was:

I-70
4 MILES
4 MINUTES

The speed limit is around 60 or 65 through Frederick.

More absurd ones:

I-76 just east of I-476

US 1
8 MILES
14 MINUTES

I-676
15 MILES
41 MINUTES

Sure. Speed limit of 55 and it's that ridiculous?

[hotdogPi]

US 1
8 MILES
14 MINUTES

I-676
15 MILES
41 MINUTES

Sure. Speed limit of 55 and it's that ridiculous?

How fast were cars actually moving? Was there a lower average speed due to high traffic?

[noelbotevera]

US 1
8 MILES
14 MINUTES

I-676
15 MILES
41 MINUTES

Sure. Speed limit of 55 and it's that ridiculous?

How fast were cars actually moving? Was there a lower average speed due to high traffic?

Traffic was moving a little faster than that and the only backup I got was near US 1.

[CtrlAltDel]

Also, did anyone read the title as "Time Travel signs"?

I did. I wondered if we might see something like this:

[kkt]

Also, did anyone read the title as "Time Travel signs"?

I did. I wondered if we might see something like this:

[OCGuy81]

Also, did anyone read the title as "Time Travel signs"?

I did. I wondered if we might see something like this:

Best get my DeLorean fired up. 88 MPH!

[odditude]

US 1
8 MILES
14 MINUTES

I-676
15 MILES
41 MINUTES

Sure. Speed limit of 55 and it's that ridiculous?

How fast were cars actually moving? Was there a lower average speed due to high traffic?

Traffic was moving a little faster than that and the only backup I got was near US 1.

those times are quite common on I-76. you probably hit the area right as a jam finished clearing.

[Buffaboy]

Depends. NYSDOT and NYSTA use a combination of E-ZPass readers mounted above the roadway and pairs of induction loops. The E-ZPass readers measure travel times between two points, while the induction loops are two closely-spaced sensors that measure speed, deriving travel time from the speed. The E-ZPass readers are quite common in the northeast, where a significant amount of vehicles have transponders, as they are easier to install.

So if I put my physics hat on, the traffic engineers that created this simply have a program where is takes the velocity of the cars passing over the loop, calculates the antiderivative, and that gives the displacement or distance to the destination and then the time is calculated?

It can't be this simple. I can't imagine what goes into it.

[vtk]

Ohio has installed some intercity travel time signs recently, and they are useless because they always overestimate the times. On SB I-71 a bit south of Columbus we have "OH 435, 22 miles, 20 minutes; I-275, 70 miles, 65 minutes". That's about 66 MPH, while the speed limit is 70 (except for the last dozen miles to 275). Even worse, heading north out of Columbus, we have "US 30, 47 miles, 46 minutes; I-76, 80 miles, 79 minutes". That's 61 MPH, and the speed limit is 70 MPH the whole way. The times displayed are never shorter than that, and rarely are they longer than that.

And even if they displayed times more than 10 minutes longer than normal, you only have a vague idea where the problem is, and no alternate route that doesn't add a lot more time anyway.

[Duke87]

These days the location services on smartphones are often used to determine speeds at which people are moving along roads. This is exactly how Waze works although this data can also be sourced from phones that don't have that app installed.

New York City has readers mounted about local streets that monitor traffic flow by readiing EZpass tags. As far as I'm aware this is the only place in the country where electronic toll tags are used for this purpose outside of a toll road itself.

Then there is the somewhat lower tech, more "traditional" method of using sensors in the roadway. Because it is impossible by this method to identify the vehicle passing the sensor, it can only measure spot speed, so any derivation of average speed from this data will involve some guesswork.

License plate readers could easily also be employed for the purpose of measuring traffic speed but I don't know if they are.



As for the times displayed on the signs themselves, some states will cap the reported average speed at the posted speed limit in order to avoid implicitly encouraging speeding. PennDOT is notorious for this - you'll see times displayed on I-95 that are equivalent to covering the distance at 55 MPH even if traffic is free flowing at 70 the whole way.

[noelbotevera]

US 1
8 MILES
14 MINUTES

I-676
15 MILES
41 MINUTES

Sure. Speed limit of 55 and it's that ridiculous?

How fast were cars actually moving? Was there a lower average speed due to high traffic?

Traffic was moving a little faster than that and the only backup I got was near US 1.

those times are quite common on I-76. you probably hit the area right as a jam finished clearing.

This was east of I-476 if you were wondering. I was on I-76 - the Schuykill.

[SteveG1988]

US 1
8 MILES
14 MINUTES

I-676
15 MILES
41 MINUTES

Sure. Speed limit of 55 and it's that ridiculous?

How fast were cars actually moving? Was there a lower average speed due to high traffic?

Traffic was moving a little faster than that and the only backup I got was near US 1.

those times are quite common on I-76. you probably hit the area right as a jam finished clearing.

This was east of I-476 if you were wondering. I was on I-76 - the Schuykill.

So an average day.

[jeffandnicole]

These days the location services on smartphones are often used to determine speeds at which people are moving along roads. This is exactly how Waze works although this data can also be sourced from phones that don't have that app installed.

New York City has readers mounted about local streets that monitor traffic flow by readiing EZpass tags. As far as I'm aware this is the only place in the country where electronic toll tags are used for this purpose outside of a toll road itself.

PennDOT uses EZ Pass readers.  They look slightly different than what you'll find in a toll plaza.  Example here: https://goo.gl/maps/vg2SL5LTsQQ2 

And NJDOT uses EZ Pass readers as well: http://www.state.nj.us/transportation/eng/elec/ITS/ITSDB.shtm , then click "Select A Device Category" to see the option for Time Travel System Sensor - EZ Pass Reader.

[cl94]

These days the location services on smartphones are often used to determine speeds at which people are moving along roads. This is exactly how Waze works although this data can also be sourced from phones that don't have that app installed.

New York City has readers mounted about local streets that monitor traffic flow by readiing EZpass tags. As far as I'm aware this is the only place in the country where electronic toll tags are used for this purpose outside of a toll road itself.

PennDOT uses EZ Pass readers.  They look slightly different than what you'll find in a toll plaza.  Example here: https://goo.gl/maps/vg2SL5LTsQQ2 

And NJDOT uses EZ Pass readers as well: http://www.state.nj.us/transportation/eng/elec/ITS/ITSDB.shtm , then click "Select A Device Category" to see the option for Time Travel System Sensor - EZ Pass Reader.

Depends. NYSDOT and NYSTA use a combination of E-ZPass readers mounted above the roadway and pairs of induction loops. The E-ZPass readers measure travel times between two points, while the induction loops are two closely-spaced sensors that measure speed, deriving travel time from the speed. The E-ZPass readers are quite common in the northeast, where a significant amount of vehicles have transponders, as they are easier to install.

Someone didn't bother to read the early posts. Almost every state in the northeast uses them extensively. Most large municipalities install E-ZPass readers because a lot of people have them and it's less disruptive than installing loops. NITTEC installs them on stuff that isn't even maintained by NYSDOT or NYSTA, including highways maintained by Buffalo and Erie County. E-ZPass data is how border crossing times at the Niagara River bridges are measured.

[GaryV]

I've been amazed at how Google Maps manages to track slowdowns.  They must process billions of incoming points of data and then spit it back out to phone apps.

[blanketcomputer]

Arizona uses loop detectors on the roadway in combination with pole-mounted passive acoustic detectors.

[cl94]

I've been amazed at how Google Maps manages to track slowdowns.  They must process billions of incoming points of data and then spit it back out to phone apps.

The GPS in your phone. Seriously. They track phone locations.

[tdindy88]

Indiana has these all over Indianapolis and Northwest Indiana. In fact, I believe I had a post here a few years ago where I erroneously titled it "Time Travel Signs" with people joking about that before I realized what I had written and changed it. The Indy ones are relatively useful when it comes to rush hour and finding out how long it may take to get to certain points but for non-rush hour periods they are about as helpful as the ones in Ohio. One thing the Indy area also has along I-65 and I-70 is posted travel times through the city and around the beltway to state which route is quicker (it's almost always the thru route, except for rush hour.)

I was recently in Los Angeles and I kept on thinking to myself, "God do you guys need these." I know they had VMSs around annoucing travel times in some spots but if only you had lots and lots of these signs all over your freeways, they could be helpful.