HOV Lanes Exposed
Carpool lane facts for the San Francisco Bay
The bottom line:
Fewer people carpool today than
before carpool lanes even existed.
Carpool lane construction increases
solo-drivers more than HOVs, by more than twice as
The facts below, all from government data,
contradict the "politically correct" facade of HOV lanes. This facade was created
by highway construction interests, including
Caltrans, to achieve their real goal: more highway
The definition of carpool is a distortion of the concept:
- 40% of carpoolers are from the same
- From a Rt. 237 questionnaire11, 51% of carpoolers
commute with a family member.
- Designating one passenger in a vehicle as a "High Occupancy
Vehicle" is a distortion of the concept. This is Low Occupancy.
Many metropolitan areas locations only allow buses and approved
vans. [The I-80 freeway is 3 persons, all other Bay Area
carpool lanes are 2 persons.]
- The logic behind HOV lanes is to give preferential treatment
to encourage commuters to change from solodriving to carpooling.
Chauffeuring the spouse to work (thus doubling the commute trip by
doing two round trips daily) or the kids to school is not a
logical criteria for preferential treatment.
Carpool lanes18 greatly increase solo drivers:
- Solodrivers accounted for 79% of 5769 vehicles added to
Montague Expressway six years after constructing the HOV lane.
This solodriver figure for San Tomas Expressway is 73% and for Rt.
237 is 63% of vehicles added to the roadway. (All vehicle counts
are when HOV lanes are activated, AM+PM commute.) Rounded off, HOV
lane construction added between 2 and 4 times as many solodrivers
as HOVs. See detailed studies by
- "Thousands of solo drivers are pouring onto our freeways and
filling spaces vacated by carpoolers" when constructing a carpool
lane, writes Gary Richards of Mercury News.5
Carpool lanes increase air pollution:
- Jean Roggenkamp, a transportation planner for BAAQMD, stated
that "Frankly, there is no reduction in auto
emissions"5 by constructing carpool lanes.
- HOV lane construction has never reduced automobiles, it has
always increased them. Even worse, it has ALWAYS increased
solodrivers and Vehicles Miles Traveled (VMT).
- The Bay Area is again in non-attainment of the Federal Clean
Air Act, despite constructing 266 mile of carpool
- Carpool lane construction is a solo driver incentive in
disguise: new solodrivers outnumber new carpoolers by (rounded
off) two to four times. This is because space is freed up in
non-carpool lanes as carpoolers move over to the newly constructed
- Re-designating an existing lane as HOV would decrease air
pollution. But in all cases carpool lanes are newly constructed
lanes or the even worse situation of allowing HOVs to use bus
lanes (the latter for the Bay Bridge). The claim that carpool
lanes decrease air pollution by RIDEs and highway construction
interests is blatently false. Their claim is also outrageous
because the purpose of this propanda is to constuct even more
highway lanes which further decreases air pollution.
- BAAQMD states that "Motor vehicles represent the largest
source of air pollution in the Bay Area."16
Fewer people carpool today than before HOV lanes existed:
- In 1980 when there were no carpool lanes, 16.3%
carpooled8 compared with 14.3%14 in
1998. This was despite constructing 266 miles of
carpool lanes7, beginning in 1982.
- A study by RIDES found
carpooling has decreased from 16.7% to 14.3% of commuters
- From census data, carpooling decreased between 1980 and
1990 in the Bay Area, from 20.5% to 15.9% of motor vehicles. As
percent of commuters (including mass transit, bicycles,
walkers), carpooling decreased from 16.3% to 12.9% in the same
- In Santa Clara County carpooling fell from 17% of commute
trips to 12.5%15 despite constructing 115 miles of
HOV lanes in that period (1982-1990), more than all other Bay
Area counties combined.
- 71% of car commuters drive alone to their jobs. The figure was
65% in 1996.8
- A likely reason for this loss in market share is that HOV lane
construction decreases travel time in other lanes, making
solodriving more attractive.
- The drop in market share of HOVs despite spending millions on
HOV lanes shows the concept is a boondoggle. No business would
spend money on something that results in a drop in market
Carpool lanes are promoted by highway construction
- "HOV lanes are a great success" claimed Santa Clara County's
highway engineers3 in their press release. In fact, it
was not a success either in reduction of VMT or of solodrivers.
Their "success" is based solely at looking at HOV counts and
deliberately ignoring solodrivers.3 "Failure" would
have been more appropriate for their press release title.
- Also not taken into account was that most of the increase in
HOVs resulted from a switch from parallel routes to the less
congested HOV lane. Paralleling routes would decrease percent of
HOVs with this scenario. While no data was taken on parallel
routes, the decrease in market share of HOVs indicates this is
occurring. The false conclusion of "success" in the press release
was based on the assumption that the entire increase in HOVs was
the result of switching from solodriving to carpooling.
- Contrary to recent propaganda by Caltrans4,
carpooling is decreasing overall. Caltrans figures only looked at
the highways that have carpool lanes (most had some increases),
and omitted ALL mention of how many solodrivers were added to the
road as a result of HOV lane construction. For example4
"The biggest jump in carpooling occurred on Interstate 680 in
Contra Costa County, rising from 495 to 1,567 people [divide
by 2 for vehicles] during the peak rush hour since 1994." Not
one word about how many solodrivers were added due to the increase
in highway capacity.
- HOV lanes are only a success when the goal is to build more
- Why does Caltrans
support carpool lanes? To quote Albert Yee, Caltrans chief of
highway operations in the Bay Area: "Carpool lanes make it much
easier to get environmental clearance" for road projects. "If we
want to add a general-purpose lane for all drivers, that's going
to get thrown out." 5 Caltrans' primary
goal is to maximize highway construction.6
Increase in Vehicles resulting from adding HOV lanes, San Tomas
Expressway (Santa Clara County).3 Vehicle counts in the
peak commute direction were taken before and two years after
increasing the lanes from 4 to 6. Data from Santa Clara County
Transportation Agency. The increase in 2-Occupant does not mean a
switch from solodriving as much as a switch from driving parallel
roads to the less congested HOV lane, thus decreasing 2-Occupant on
paralleling routes. When this figure was made, the definition of HOV
nationally was at least three occupants.
Carpool lanes reduce mass transit usage, increase
- Note: this section is applicable to the case of constructing
HOV lanes parallel to a significant transit corridor, and the only
corridor this occurred was I-80 (in the Bay Area).
- A recent RIDES study13 states there would be "fewer
cars on the road if casual carpooling were not an option." The
newly constructed lane on I-80 increased car usage as many
carpoolers previously took public transit: 74%
of carpooling passengers and 33% of drivers switched from using
transit according to the RIDES survey.17
- The increase in automobiles from the increase in solodrivers
is undoubtedly much greater than the increase in automobiles due
to switching from public transit to carpooling (about 600 cars per
day, says RIDES). Unfortunately, RIDES did not study how many
solodrivers were added to the road as a result of lane
construction, nor how many of these switched to solodriving from
mass transit due to the temporary reduction in travel time on the
roadway. Future studies need to query solodrivers to get this
Solution for carpool lanes:
- Change HOV lanes into fare lanes or HOT lanes [High
Occupancy Toll lanes].
- HOT lanes are more efficient than carpool lanes, as any unused
capacity of a carpool lane is used by people paying a fare that
varies depending on demand. It is called congestion pricing.
- Use of congestion pricing is not only fair, it is the only way
to eliminate traffic congestion.
- Politically, this should end pressure for more highway
- After a testing period, also change existing general lanes, at
least half of a freeway, into fare lanes or HOT lanes.
- Above all, stop highway construction including using HOV
designation as a ruse!
Three reasons why carpool lanes harm mass transit:
- Carpool lanes greatly increase solodriving, the main
competitor to transit in the urban transportation market.
- The minority HOV lane users who actually switch from other
modes are mostly former transit patrons (on a corridor with
significant transit usage or if a major transit line is built in
- Decreasing automobile travel time probably decreases transit
usage, a deduction of simple marketing principles applied to the
urban transportation market. [This is the only statement that
does not have data backing up the point, because there is no data
to my knowledge.]
This page was compiled by Akos
Szoboszlay, an engineer and President of the Modern Transit
Articles by the Modern Transit
Also see the Federal Transit Administration
web site about HOV lanes:
1 Source: RIDES study quoted in
Mercury News 1/24/99, p. 4B
2 Mercury News 1/24/99, p. 4B
3 HOV lanes cause huge solo driver
increase on Montague Expressway; Traffic
engineers' disinformation on HOVs:
HOV lanes cause huge solo driver
increase on San Tomas Expressway and Rt. 237:
4 "Carpool Trivia" by Caltrans in Mercury News, 1/24/99, p.
5 Mercury News, 10/18/97, p. 1A, 22A.
6 Caltrans' unstated goal: moderntransit.org/ctc/ctc07.html#caltrans
7 Non-attainment of Clean Air Act at BAAQMD web site at http://sparc2.baaqmd.gov/sip/aboutsip.htm.
Web page is called BAAQMD SIP.
8 RIDES report "How Bay Area Residents Commute," Table 5, on web
9 Much detail provided by the Free Market for Transportation Plan
by the Modern Transit Society at moderntransit.org/fmt
10 Details in U.S. News&World Report, 2/8/99, p. 28
11 From a Rt. 237 questionnaire [Caltrans report dated March
12 Employee Parking Cashout
and Results of 10
13 Rides report at http://www.rides.org/lv2corner/lv3ccrpt/cc3survey6.html
The report continues by clicking "next" or click "index."
14 Source: MTC Working Paper 5 from their web site, Table23.XLS.
This is abridged on our website at
The original is at http://www.mtc.ca.gov/datamart/census.htm#WP
(zipped, exel, win file).
15 "Demographics, Trends and Air Quality Working Paper" by SCCTA,
dated Dec. 1990, page 37.
16 Letter from BAAQMD to MTC re: MTC's RTP, dated 9/30/98, page 1.
From BAAQMD web site. File is mtclet.pdf
17 RIDES data on web page
The report continues by clicking "next" or click "index."
18 Carpool lanes are also called HOV lanes or diamond lanes. The
original term is High Occupancy Vehicle [HOV] lanes.
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