Delays due to "volume"

[02 Park Ave]

One often hears on traffic reports "Delays due to volume."

Wouldn't it be more accurate if the reason given for a back-up was "Delays due to inadequate roadway capacity."?

[MNHighwayMan]

Not necessarily. The road may have adequate capacity on any given day but a one-off occurrence (accident, etc) may be causing a backup due to temporarily reduced capacity.

[BrianP]

I'd think that saying volume is more accurate.  If you expand what they are saying it would be 'Delays due to more volume than the road can handle.'  It could point to a capacity problem.  But it could also point to a design problem like insufficient entrance and exit ramps (too short or no merge area).  Or it could be weaving due to a mix of on and off ramps.  Or it may be due to bad road geometry.  Or it could be poorly timed traffic signals.  So delays, especially ones that occurs regularly due to rush hour, points to a problem.  But not necessarily what the problem is. 

Now if you have slow traffic because of a lane drop.  Then that's more likely a capacity problem.  But even that could just be people are bad at merging.

[sparker]

One often hears on traffic reports "Delays due to volume."

Wouldn't it be more accurate if the reason given for a back-up was "Delays due to inadequate roadway capacity."?

That must be a phrase (volume) used on the East Coast; out here the term most heard in traffic reports is "congestion", or "backup" -- the latter principally employed when a traffic incident is involved.  For better or worse, we've pretty much internalized the congestion phenomenon (both in my neck of the woods, the Bay area, as well as down in greater L.A. and even San Diego) within west coast metro areas.   For the most part, there's really not sufficient room to attempt to increase capacity systemwise; some older arteries (e.g. I-5 from the east side of L.A. down to Orange County) have seen recent upgrades, including significant capacity increases; but trying to add lanes, whether express or general-purpose, is often rife with obstacles (neighborhood objections, litigation, etc.) -- things certainly not historically foreign to East Coast venues as well.  Some exurban freeways that were constructed later and designed for expansion (like I-15 in the "Inland Empire" near Ontario) are getting capacity-increase projects just as likely to be tolled as not. 

So join the club.  The mantra "you can't build your way out of congestion" seems to have taken hold with many transportation agencies nationwide -- now whether it is indicative of an ideological shift, or simply a rationale to justify slashing, postponing, or downsizing expensive project concepts has yet TBD (I would suspect more of the latter, with a modicum of the former in and around dense urban venues).   But with the PIRG's, Citylab, and other like-minded entities on the warpath, it's hard enough to keep the facilities currently in use intact much less suggest substantial systemic expansion.  The 21st century transportation arena is constantly evolving, with new automotive corridors in NC and TX juxtaposed with teardown efforts in Syracuse, the Bronx, and other locations.   All I can really say is it's going to be a bumpy ride! 

[jeffandnicole]

Should they also say "traffic is moving fine because the roadway was overbuilt and has excess capacity?"

That must be a phrase (volume) used on the East Coast

A little bit. Also personal preference. NJDOT likes using volume when there's just delays due to too much traffic.  Some reporters will switch between jam, congestion and volume just so they're not repeating themselves.

[Mapmikey]

Around here, volume (which is always turned up to 11) is very frequently used to differentiate from accident, disabled vehicle or police activity during traffic reports.

[SteveG1988]

KBBL Needs to turn down their power in your area

[kphoger]

One often hears on traffic reports "Delays due to volume."

I just turn my radio down.  If we all do that, then the overall volume will decrease.

[webny99]

Not necessarily. The road may have adequate capacity on any given day but a one-off occurrence (accident, etc) may be causing a backup due to temporarily reduced capacity.

In those cases, the problem is reduced capacity, not increased volume, so it should be framed as a capacity problem:
"Accident Ahead, Right Lane Blocked"; "Lane Closed for Construction"; etc.

There are other cases where capacity is unchanged, but temporarily increased volume causes issues:
-Holiday travel on a rural interstate
-Traffic en route to a popular weekend getaway
-Traffic near a seasonal/time-sensitive tourist destination
-Congestion in the vicinity a major event or festival
-Mall traffic between Black Friday and New Years

Framing any of the above as a volume-related problem would be perfectly acceptable.
Or even after a major traffic incident like an accident; as it clears up, you will start seeing maximum volume moving downstream. "Delays due to volume" would be appropriate for the temporary pinch points that pop up elsewhere as everyone starts moving, but not at the site of the accident itself.
Same for a construction related closure: "Delays due to volume" shouldn't be used on the road that's closing; if anything there should be less volume than usual! But for the detour route for the closure, it is acceptable and even encouraged to warn motorists that there may be volume-induced delays.

Obviously, the worst is when it's both: An accident blocking a lane of the Thruway on a holiday weekend, for example. In that case, identify the biggest problem first: the reduced capacity. The rest should be self-explanatory.

One often hears on traffic reports "Delays due to volume."
Wouldn't it be more accurate if the reason given for a back-up was "Delays due to inadequate roadway capacity."?

I think the above sufficiently covers all aspects of your inquiry!
TL; DR, totally depends on whether the root cause of the problem is decreased capacity or increased volume. Anything normal/recurring shouldn't need any clarification, simply "the usual traffic/congestion at XX" would suffice.

[Bruce]

Amazingly, there's a phenomenon that describes what happens when you build sprawling suburbs without proper regulations while also neglecting to upzone areas near employment and encouraging non-driving options. You'd never be able to build enough lanes to fit every potential car driver in 2050 or 2100 or the heat death of the universe.

[english si]

In the UK we call it 'sheer weight of traffic'. Don't tend to hear it so much anymore now they manage it and iron out the ghost jams with variable speed limits on the busier motorways. But driving at 40mph on a motorway feels odd even though it's quicker (and safer) than driving 70mph into stationary traffic sitting there for a few minutes and then setting off again with no blockage in front of you.

Bruce - the M25 is possibly the gold plate example of this problem. It runs through one of the strictest planning regimes on the planet for basic land of little conservation value (the green belt) - though large parts of the surrounding area also have the same conservation as British National Parks on top of that. The suburbs are mostly built up around the extensive rail network and are having all the uprating and densification done for it - especially the ones inside the motorway ring (where also the buses are cheap and frequent). The problem is not sprawl, or lax planning, or lack of transit - the problem is that it's an insufficient road network for the population 20 years ago, let alone now with about 1.5 times the population (my near M25 town has doubled in population since 1991 without much increase in area).

Arguably the uprating near employment hubs has exacerbated the issue, as towns in Outer London and just beyond have become more attractive destinations due to the snowballing of employment and residential capacity in them and less commute into Central London (well, a smaller proportion), meaning traffic between these towns has grown.