The moment of truth for HOV lanes has arrived in California. In June, the federal government informed Caltrans that the state is out of compliance with minimum federal standards that require such lanes to flow at an average rush-hour speed of at least 45 mph. The standard exists because HOV lanes are supposed to reward those who give up solo driving (by joining a carpool) with faster trips. On some of the most-congested Southern California freeways, rush-hour HOV lanes run at 10 mph or less. Congestion is also plaguing several HOV lanes in the San Francisco Bay Area.
Thus far, the fixes being discussed by Caltrans are mostly tinkering, such as limiting the number of hybrids allowed to use the lanes, extending the hours that "diamond lane" versions are in operation, standardizing policy on where drivers can enter and exit HOV lanes, beefing up patrol-car enforcement, and (perhaps) increasing the required occupancy from two persons to three. (Currently, only a handful of California's HOV lanes require three occupants.)
How California addresses this problem matters, since the state has far more HOV lanes (1,350 lane-miles worth) than any other state, and plans to add 950 lane-miles more. Getting this wrong will have major consequences for California motorists, whereas breaking new ground could set an example for other states that are nowhere near as far along in implementing HOV or HOT lanes.
The proposed solutions don't cope with the real failings of HOV lanes as currently operated in America. First, they don't address the major problem of "fampooling." As Alan Pisarski, author of Commuting in America, has concluded, the traditional commuter carpool (two or more employees riding together to work) has "functionally disappeared." Pisarski estimates that up to 80% of "carpools" consist of family members who would be riding together anyway; hence, "fampools" result in no reduction in rush-hour traffic, but simply get a slightly faster ride in the HOV lane.
Enforcement is the second problem. There is still no reliable technology for counting heads in moving vehicles (especially when eligible heads include infants in back-seat car-seats). Reliable figures on outright cheating in HOV lanes are hard to come by, but in traffic studies I've seen recently, violation rates are often in the 20% range.
The third problem is that the congestion relief offered by HOV lanes is not sustainable. Over time, in growing metro areas, the lanes fill up and lose their time-saving advantage. If and when the political hurdles to upping the requirement from HOV-2 to HOV-3 can be overcome, there is then a new problem of "empty-lane syndrome," since three-person carpools (or "fampools") are a lot harder to form and maintain than two-person ones. Hence, the powerful case for switching from HOV to HOT (which is apparently not part of Caltrans' set of near-term options).
In fact, it is only those metro areas that are looking seriously at priced lanes that are coming to grips with the shortcomings of HOV lanes. In San Diego, SANDAG has funded research on ways of improving HOT lanes enforcement. One of the alternatives proposed in that research was to redefine carpool to address the "fampool" problem and return to the original commuter ride-sharing/trip-reduction purpose of HOV lanes. The breakthrough idea was to limit eligibility for free passage to pre-registered carpools and vanpools. Those vehicles would get specially coded transponders authorizing free passage. Hence, manual enforcement (via patrol cars) could be eliminated—no more counting heads. Instead, the burden would be on whoever registered the carpool—presumably employers participating in a ride-sharing program—to make sure the carpool was, and remained, legitimate and hence entitled to use the transponder.
To the best of my knowledge, the first jurisdiction that plans to do this is the Florida DOT. In their Urban Partnership proposal to the U.S. DOT for converting the HOV lanes on I-95 in Miami to managed lanes, they would simultaneously up the occupancy required for free passage from two to three and limit eligibility to employer-certified carpools. If they actually implement the proposed I-95 Express Lanes in this manner, it will be a national breakthrough.
In a paper I presented at the Institute of Transportation Engineers technical conference in San Diego this spring, I crunched some numbers to compare the performance of various types of HOV, HOT and express toll lanes. In that analysis, the best combination of person throughput and revenue was what I defined as SHOT (super high occupancy toll) lanes, in which only buses and vanpools went for free. I have just added a HOT-3EC alternative to that spreadsheet, and am pleased to see that it produces almost as much revenue (85%) as the SHOT lane, and 93% as much person throughput. So the Employer-Certified HOT-3 configuration would appear to be a way to continue an explicit incentive for ride-sharing without giving away most of the revenue potential (as is done with today's common HOT-2 configurations).
I still think the pure SHOT or Express Toll Lane is the superior way to go. And for urban areas like Atlanta with few or no HOV lanes already in place, that approach is simpler and maximizes revenue. But in places like Los Angeles and the San Francisco Bay Area, with very extensive HOV systems (and a large HOV user base), the HOT-3EC approach would be a realistic compromise. It would solve all three problems that plague HOV lanes—"fampools," enforcement, and sustainability—while producing robust revenue for building out a seamless network of priced lanes.