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Open Access Publications from the University of California

The University of California Transportation Center recognizes that transportation is one component of a societal system that is affected by and has effects on the movement of goods, people, and information. The Center draws on the knowledge of many disciplines, including but not limited to engineering, economics, urban planning, and management in its efforts to support studies that analyze transportation systems and the public policies that are integral to them.

The Center is sponsored by both the United States Department of Transportation (DOT) and the California Department of Transportation (Caltrans). All transportation-related programs within the University of California campuses are eligible for research and educational funding from the Center. The primary campuses involved in UCTC activities are those at Los Angeles, Davis, Irvine, and Berkeley.

UCTC maintains an active program of basic and applied research conducted by University of California faculty and graduate student assistants. The Center supports the University's educational programs in transportation with awards of scholarships and fellowships to students planning careers in transportation. As part of its technology-transfer activities, UCTC sponsors seminars and conferences where scholars and public officials meet to exchange information and research findings. The Center also publishes the results of research it has funded in the form of working papers, reprints of journal articles, and in its official magazine, ACCESS. These publications are distributed widely within the academic, professional, and governmental communities.

Cover page of Why Do Building Owners Invest in Bicycle-Oriented Design?

Why Do Building Owners Invest in Bicycle-Oriented Design?


Bicycle infrastructure design has largely emphasized bicycle lanes and paths, with little attention to the facilities at trip’s end—those which address bicyclists’ needs for security for their bicycle and belongings, shelter from the weather, and making the transition from bicycle rider. These elements comprise what we are calling “bicycle-oriented design” (BOD) and include covered and secure parking, storage for clothing and equipment, and showers and changing rooms. Similar to the concept that in transit-oriented development (TOD), a transit traveler becomes a pedestrian over the course of the entire trip, BOD reflects that a bicyclist becomes something other than a bicyclist at the journey’s end. 

Cover page of Estimating Emissions Using an Integrated Traffic Model

Estimating Emissions Using an Integrated Traffic Model


Currently, there is no efficient way to estimate emissions from traffic on big transportation networks, such as the freeway links that connect downtown Los Angeles to the San Pedro Bay Ports complex. This transportation corridor is particularly vital because the ports handle more than a third of the U.S. container trade. Yet the economic vitality of this area is threatened by congestion and air pollution from freight operations.

Cover page of Charge It: The Promise of Plug-in Electric Hybrids

Charge It: The Promise of Plug-in Electric Hybrids


With rising energy prices and battery improvements, the plug-in hybrid electric vehicle, a variant of the betterknown self-charging hybrid electric vehicle, is fast gaining popularity. Because plug-in hybrids can recharge via a wall socket while resting, they can run purely on electric power for many trips without having to revert to gasoline. This significantly reduces emissions over conventional hybrids, which can only recharge while they’re operating and are thus more likely to rely on their internal combustion engine when in use. The driving range of plug-in hybrids running on electricity varies from 10 to 60 miles. Surveys show that about 50 percent of passenger vehicles in California log fewer than 20 miles in a day; about 80 percent log fewer than 60 miles. Such short trips are well-suited to purely electric-powered travel.

Cover page of Health Impacts of Moving Freight In and Out of the Ports of Long Beach and Los Angeles

Health Impacts of Moving Freight In and Out of the Ports of Long Beach and Los Angeles


The San Pedro Bay Port (SPBP) of Los Angeles and Long Beach is the largest container port in the U.S. Although the benefits of handling and hauling freight are enjoyed by the nation as a whole, the traffic congestion and air pollution created by the port falls mostly on the people who live and work nearby and along connecting freight corridors. These corridors include two busy freeways, the I-710 and the I-110, and an active rail link, the Alameda corridor. 

This research studied the environmental and health impacts of freight operations between the SPBP and downtown Los Angeles, some 22 miles to the north. In our analysis of health impacts, we focused on nitrogen oxide (NOX), a contributor to the formation of photo-chemical smog, and fine-grain particulates (PM10), which can lodge in peoples’ lungs with repeated exposure. We combined estimates of air pollutants from the I-710 and I-110 freeways, line-haul rail lines, and rail yards and looked at them for summer and winter. Four models were linked together to assess impacts: a microscopic traffic simulation model (TransModeler), which describes vehicle behavior; an emissions model (EMFAC 2007), which estimates the impacts of congestion on air pollution; a pollutant dispersion model (CALPUFF), which calculates how emissions move in a region’s atmosphere; and a health impact model (BenMAP), which calculates various pollutants’ effects on health using the incidence of various pollution-related illnesses.

Cover page of "Intelligent" Ways to Cut Transportation's CO2 Emissions

"Intelligent" Ways to Cut Transportation's CO2 Emissions


Most policies to cut the transportation sector’s CO2 emissions focus on fuel-efficient vehicles, low-carbon fuels, and reductions in vehicle-miles traveled. One strategy that gets less attention but has high potential pay-off is Intelligent Transportation Systems (ITS). An example is variable speed limits on freeways, illustrated in the photo below. Under this scheme, motorists are alerted of downstream congestion and the adjusted posted speed limits help maintain a steadier, more even flow. Reducing the amount of stop-and-go traffic can significantly cut down on tailpipe emissions and fuel waste.

Some studies suggest that the carbon reduction benefits of ITS are minimal. For example, the recently released “Moving Cooler” report, prepared by Cambridge Systematics, estimates that ITS would reduce emissions by less than 1% nationwide. Others contend that ITS projects could induce new travel that offset some of the gains. We believe that these analyses fail to include key calculations that cast ITS in a more favorable light.

Cover page of Repricing Highway Pavement Deterioration

Repricing Highway Pavement Deterioration


Different highway agencies use different maintenance strategies. Our research indicates that each agency should compute its own cost estimates of maintenance on the basis of: • the measure of pavement performance that it uses to trigger maintenance (and accordingly, the appropriate value of the axle load power which is not necessarily equal to four), • and the actual maintenance activities and policies that it uses (which are not necessarily thick overlays applied at regular time intervals).

If agencies were to move toward more realistic cost estimates, they would be able to better forecast maintenance costs and plan their maintenance programs accordingly. They also could establish fees that would be more equitable across truck sizes and potentially even raise additional needed dollars.

Cover page of The Price of Unwanted Parking

The Price of Unwanted Parking


When a city requires on-site parking for all new housing, housing costs rise while the price of driving falls. This results in less housing and more driving. Minimum parking requirements are particularly troublesome for old, dense inner city neighborhoods. Many buildings constructed before World War II don’t have parking attached to them, and in dense center cities—where land is expensive, and lot sizes are small and irregular—parking can be extraordinarily expensive, if not impossible, to provide on-site. Thus many older in-city buildings sit unused, simply because they can’t provide enough parking to satisfy the zoning code.

Measuring how parking requirements affect housing construction is difficult for a simple reason: parking requirements are everywhere. There is good theoretical reason to believe that relaxed parking requirements would result in more housing, and developers regularly say that left to their own devices, they would supply less parking. But because developers are almost never left to their own devices, the theory is hard to test.

Cover page of Are TOD's Over-Parked?

Are TOD's Over-Parked?


Just as land-use environments vary throughout suburban America, so should parking policies. Parking ordinances should be more flexible for projects situated near rail stops. Based on our research, for example, developers of relatively dense apartments with adjoining retail shops and short, direct walking connections to rail stations should have the option of supplying fewer parking spaces than the norm. Flexibility might also take the form of unbundling the cost of parking from the cost of renting housing or providing residents with the option of choosing transit eco-passes rather than paying for an on-site space. And in light of the fact that TOD residents were found to commute by transit proportionately more than they shed cars or reduced parking, car-sharing should be provided in as many rail-served neighborhoods as possible. Putting shared-cars in and around TODs could relieve many households from owning a second car or a vehicle altogether, which would result in not only considerably lower trip generation rates, but considerably less parking demand as well.