Federal Social Experiments with Human Behavior Don’t Always Work as Intended — Moving Previously Authorized Single-Occupant Hybrid Cars Out of Car Pool Lanes in the San Francisco Bay Area Slowed All Lanes of Traffic — and A Related Observation about Silliness in Government

05 November 2011

Federal regulations are sometimes meddlesomely backward

U.S. government regulations used to permit single-occupant hybrid vehicles in car pool lanes. The idea was to encourage people’s embrace of fuel efficient vehicles.

But, in August 2005, federal regulations required the states to withhold this permission, if car pool lanes slowed to below 45 mph at least 10 percent of the time.

Note

This regulation is called SAFETEA-LU section 1121 (2005).

You can read about the 45 mph restriction in 23 U.S.C. [United States Code] § [section] 166(d) here.

In other words, the states were now required to “boot” single-occupant hybrids out of high occupancy vehicle (HOV) lanes, if those lanes slowed to below 45 mph for more than 10 percent of the time they were in operation.

So California did exactly that in July 2011 and the result was slowed traffic in all lanes.

A UC-Berkeley Institute of Transportation study examined what happened

A University of California at Berkeley study now demonstrates that, after California booted hybrids from the car pool lanes (in keeping with the requirements of federal law), all lanes of traffic slowed by 11 to 12 percent.

Citation

Kitae Jang and Michael J. Cassidy, Dual Influences on Vehicle Speeds in Special-Use Lanes and Policy Implications, Institute of Transportation Studies University of California – Berkeley (September 2011)

What the UC-Berkeley study showed

The study began with the researchers’ prediction of what probably would happen, after the hybrids got the boot, based on the team’s mathematical (“kinematic wave”) modeling of traffic flows:

Thus, we predict that the SAFETEA-LU regulation can increase a rush period’s PHT [People Hours Traveled] at the site by more than 400 person-hours, a 12% increase.

In similar fashion . . . the regulation can increase the total rush-period Vehicle Hours Traveled, the VHT, by roughly 11%.

© 2011 Kitae Jang and Michael J. Cassidy, Dual Influences on Vehicle Speeds in Special-Use Lanes and Policy Implications, Institute of Transportation Studies University of California – Berkeley, at page 8 (September 2011) (paragraph split)

California’s federally compliant decision not to renew the single-occupancy HOV exception for hybrids gave the researchers a way to test their predictions:

The resulting prohibition, which took effect on July 1, 2011, has affected 85,000 LEVs statewide . . . .

Consequently, the LEVs [Low-Emitting Vehicles, e.g. hybrids] totaling 1.2% of our site’s traffic demand are now banned from its carpool lane. This new state of affairs affords us opportunity to test our predictions against real data.

The data are limited: as of this writing, California’s new policy has been in effect for little more than 2 months. The preliminary assessment to follow is instructive nonetheless.

[W]e see that the measured average speeds in the carpool lane did in fact diminish following LEV expulsion.

Travel conditions in the regular lanes erode as well, as migrating LEVs cause the regular-lane queue to expand spatially and temporally.

Why does this slowing happen?

Presumably,

(a) the increased congestion (caused by the return of the hybrids) in the regular traffic lanes slowed them down,

and

(b) the subsequent regular lane slowing, combined with exits and entries to and from the car pool lane, caused sensible drivers in the faster lane to slow down for safety reasons.

Sane people don’t want to be zooming by at 70 mph in the high occupancy vehicle (HOV) lane, when the cars in the adjacent regular lane are traveling at 20 to 30 mph. You never know when one of these slower-moving cars is going to pull out in front of you.

So what about the logic of the federal regulation?

The research team questioned the federal government’s logic in coming up its “boot the hybrids” logic.

Even if we can set aside the damages that will apparently result from the SAFETEA-LU regulation, we would remain puzzled by its logic.

The regulation’s objective – to maintain a carpool lane’s speeds at or above 45 mph for 90% of its operating hours – seems off-target.

After all, the literature indicates that a carpool lane’s attractiveness to commuters is based less on the magnitude of its speed than on the quality of travel that it provides relative to that of the adjacent regular-use lanes . . . .

From what we have seen, even slow-moving carpool lanes tend to perform well by this relative standard . . . . Moreover, carpool lanes are probably most attractive when regular-lane speeds are especially slow, even though the carpool-lane speeds would therefore be slow as well.

We are further puzzled by the regulation’s use of speed as its metric of choice. It seems that a facility can be classified as a “degraded” one based even on the speeds that occur over short segments of a carpool lane.

The literature indicates that travelers are more concerned about the trip times over their entire journeys than they are about their shorter-run speeds . . . .

The moral? — Government intrusions into molding human behavior aren’t necessarily bad, but one does have to be prepared for occasionally unintended consequences — and it helps to keep the larger national goals in mind

The SAFETEA-LU section 1121 demonstrates two frequent problems with federal meddling — the government’s failure to real world test (before implementing regulations) and its often annoying failure to see the big social picture.

The UC-Berkeley transportation study indicates that the federal HOV regulation has the opposite effect of what it intended.

And, more broadly, one would think that policy choices would benefit from keeping overall national goals in mind.

For example, which of the following alternatives makes more sense nationally:

(a) letting a bunch of gas guzzlers — which are almost certainly driven by single-occupants most of the time — speed by the rest of us the few times they are hauling a passenger or two (which was SAFETEA-LU section 1121’s intent),

or —

(b) sticking with the arguably more important energy policy that had encouraged the adoption of more efficient vehicles by permitting hybrids to use HOV lanes?

In essence, the federal SAFETEA-LU amendment:

(i) slowed traffic,

(ii) burned more fuel (due to increased congestion and stop-and-go-itis),

and

(iii) discouraged the adoption of increased fuel efficiency.

That’s like losing your cake and choking on it at the same time.

PeteFree.com

Federal Social Experiments with Human Behavior Don’t Always Work as Intended — Moving Previously Authorized Single-Occupant Hybrid Cars Out of Car Pool Lanes in the San Francisco Bay Area Slowed All Lanes of Traffic — and A Related Observation about Silliness in Government