Understanding Transportation Issues
Measure Y in El Dorado County, approved by the voters in 1998, mandates that developers pay fees to fund road improvements to mitigate traffic congestion caused by increasing numbers of new homes. HOV lanes, partially funded by $15 million paid by El Dorado County, have recently opened for portions of Highway 50 enroute to Sacramento. Because of a four-year delay by the Board of Supervisors in implementing Measure Y, none of this cost was paid by developers of El Dorado County properties, however. Caltrans has just announced a plan to widen Highway 50 through Placerville in part by taking space just south of the freeway that is part of the old railroad corridor that prior plans had proposed to use as part of a multipurpose trail extending west to the county line and beyond. Caltrans admits that post-construction traffic will be relieved for only a few years by this project.
Are these approaches to solving traffic congestion likely to succeed? Many of us have heard the expression, "It only encourages them," referring to road-improvements such as those mentioned in the preceding paragraph. Is there research bearing out this view? Emphatically yes. In fact, transportation authority Anthony Downs first set forth his Principle of Triple Convergence in the 1960s and elaborated upon it in a 1992 book, Stuck in Traffic, written for a non-technical audience.
The Principle of Triple Convergence
Briefly, Downs's Principle states that, unless a community is essentially stagnant in growth, adding new road capacity is doomed to fail because that new capacity will attract three groups who had avoided (and thereby eased) peak-hour congestion by:
- using alternative routes
- traveling at off-peak hours
- using public transit
As Downs says, "Expansion of road capacity-no matter how large, within the limits of feasibility-cannot fully eliminate periods of crawling along on expressways at frustratingly low speeds." Rapid growth, as El Dorado County has been experiencing, overwhelms any remedies to reduce congestion, such as highway capacity improvements.
Supply-Side Remedies
Downs divides proposed remedies into those affecting supply and those affecting demand. On the supply side, he lists several ways of increasing capacity: 1) building more roads, 2) increasing efficiency of existing roads in any of several ways, 3) adding HOV lanes, 4) making more public transit available, and 5) administering public transportation systems. None of these is likely to prove effective, he argues, as follows:
BUILDING MORE ROADS: This tends to be counterproductive because of triple convergence.
INCREASED EFFICIENCY: This would include improved maintenance, better timing of signals, patrol by a fleet of repair vehicles, television monitoring, upgraded arterials, one-way streets, ramp signals, provision of real-time traffic information, and changed parking patterns. Nevertheless, traffic increasing with growth will soon overpower any of these factors.
HOV LANES: Conversion of existing lanes, Downs says, is ineffective: it reduces capacity and fosters cheating and driver anger.
MORE PUBLIC TRANSIT: It is most used by those who have no car, live in a central city and work in the central business district, or live in densely-settled communities. It is little used in suburbs. Even if policy changes could double the numbers of suburban users, growth would soon wipe out any gains. Only restraints on car use and increased density of development are likely to have a positive effect. The cost of rail without federal subsidies is prohibitive, while increased bus service, though less costly, needs to be done in association with HOV or other reserved lanes for their use. Light rail, Downs judges, though less costly than heavy rail, probably is little, if any, more effective.
ADMINISTRATION OF PUBLIC TRANSPORTATION SYSTEMS: Most public transit systems, notes Downs, require large subsidies.
Demand-Side Remedies
Downs divides demand-side remedies into ones that don't change housing/job locations and ones that focus on behavior. Of the former, he cites peak-hour road pricing. This has never been completely tried in any metropolitan area because of issues of equity (it favors the economically better off, though the fees collected could be redistributed to subsidize low-income people or to improve the road and transit systems), issues of efficiency (technology exists to use electronic sensors rather than have delays at toll booths), issues of privacy (these could be overcome by using pre-paid cards that would record a vehicle's whereabouts only when the value is exhausted), and issues of transient vehicles (toll booths could be used for these). A variation would be zone pricing, whereby there would be a charge for entering heavily congested areas, again tracked by electronic sensors. Private toll roads, says Downs, are usually priced to generate a profit, not to relieve congestion.
As to demand-side remedies that focus on behavior, Downs lists 1)shifting peak-hour trips to other times by means of staggered work hours and "flextime", 2) working at home, 3) restricting use of vehicles to certain days, 4) ride-sharing, 5) raising the cost of using private cars, 6) raising the cost of parking, 7) encouraging use of public transit for trips associated with work, and 8) exploring so-called Intelligent Vehicle Highway Systems.
SHIFTING PEAK-HOUR TRIPS: Policies such as cooperatively staggered work hours, flextime policies, or shortened work weeks possibly combined with longer work days. The potential for improving congestions is limited, but perhaps could be increased by combining this approach with others, Downs says.
WORKING AT HOME: So-called "telecommuting" has contributed to growth of this practice, though it is likely to remain part-time for several practical reasons. However, Downs gives several means by which it could be fostered. A regional, perhaps ever state-wide approach (if tax provisions were to be used to encourage it), would be needed.
RESTRICTING VEHICLE USE: Tried in some places is restricting vehicle use to certain days by some means such as license number. Those restricted would have to stay home or use other transportation. This would be a hardship on those who had to go to work.
RIDE-SHARING: One way to accomplish this would be by strong pressure on employers to persuade workers to ride-share. Having to pay for parking if one drives alone, while providing free parking to those using car- or van-pools would be one way. Downs discusses several others.
RAISING THE COST OF USING PRIVATE CARS: Downs judges this approach as having the most potential but notes that it is the least popular. It undoubtedly would be hard on low-income families, though techniques exist to mitigate the effect. Relative to the cost in other countries, the cost of gasoline is low in the United States. Increasing the tax and allowing the cost to rise could at least drive a switch to vehicles with better mileage, just as the crisis of the early 1970s did, and would encourage ride-sharing or use of transit, where it is available. Raising sales or import taxes on vehicles, tried in Denmark, would discourage vehicle ownership rather than focus on peak-hour traffic, but is likely to prove very unpopular in the United States.
RAISING THE COST OF PARKING: Free parking, often offered by employers, encourages the use of private cars. Its elimination would discourage driving alone and encourage at least car-pooling, if not use of public transit. Another approach would be to raise parking fees for those entering facilities during peak commuting hours and reserving lower fees for mid-day shoppers and others.
ENCOURAGING USE OF PUBLIC TRANSIT: Unfortunately, especially in areas where public transit is limited to non-existent, it is very difficult to persuade solo drivers to give up the convenience and comfort of personal cars.
INTELLIGENT VEHICLE HIGHWAY SYSTEMS: This high-tech approach involves gathering information on conditions in real-time, adjusting signals and ramp metering devices accordingly, effectively making information available to drivers, and automated control devices on vehicles, roadways, or both. Because these approaches are costly and do not reduce numbers on the highways, they may not be particularly cost-effective, Downs judges. At any rate, any implementation is probably years away.
Braess's Paradox
Another pessimistic view about curing traffic congestion comes from Braess's Paradox, first expressed by a German mathematician in 1968 and supported by several studies reported since by German theoretical physicists in journals like Physical Review Letters, Journal of Physics, and Nature. This says, essentially, that increasing road capacity can itself cause increased congestion, even without the addition of more drivers.
Applicability
Unfortunately, in the metropolitan Sacramento area and counties such as El Dorado, past and on-going sprawling, automobile-dependent development patterns have created conditions that make it very difficult to cure traffic congestion. Approaches by governmental entities, such as SACOG's (Sacramento Area Council of Governments) Metropolitan Transportation Plan, continue to emphasize road improvements in both planning and funding approaches to traffic congestion.
Hidden in an appendix to the environmental documents associated with the invalidated
general plan adopted by El Dorado County in 1996 was the little-noticed projection that, even with certain improvements to Highway 50, by buildout travel from Silva Valley Parkway to downtown Sacramento would take two and a half hours at an average speed of about ten miles an hour. It is anticipated now that, based exclusively on already-approved large developments and allowing none else, the county still cannot comply with Measure Y.
Though developers have benefitted from four years of not having to pay road-improvement fees required by Measure Y (see first paragraph), they are beginning to be hit by them. Will the price tag encourage them to take another look at their existing project designs and make them less automobile dependent and more transit friendly? Only time will tell.
Is the only likely "successful" approach simply to allow congestion to deteriorate to the point that people opt to live closer to work? Roger Lewis, a professor of architecture at the University of Maryland, practicing architect, and columnist for the Washington Post, writes, "One could argue that, in the long run, it's theoretically desirable to promote development and allow traffic friction to reach the point at which people willingly choose not to drive everywhere. Ultimately, the theoretical argument continues, congested road networks will decongest as more people become accustomed to using transit and other modes of transportation." Something along that line is now being practiced In Vancouver and, locally, by the City of Davis.
