Click for next page ( 122

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 121
Developments (TODs). Prepared for Transportation Northwest (TransNow), Seattle, WA (May, 2006b). Baltimore Region TOD and Smart Growth Analysis Situation. Like most U.S. metropolitan areas, particularly those in the industrial Northeast, the Baltimore region has undergone major transformation over the past 30 years. An industrial econ- omy has given way to one more focused on technology, and population and jobs have steadily dis- persed from the urban core to the surrounding suburbs and one-time rural areas. Between 1980 and 2000, Baltimore City lost more than 135,000 people and 43,000 jobs, despite the fact that the overall region grew by 341,000 people and 393,000 jobs. The effects of these shifts--from places of urban character (moderate to high density, mix of uses, and accessible by transit or walking) to outlying areas (typically automobile-oriented land use)--on transportation system demand, mobility, and air quality have been substantial. While population has grown by only 16 percent during this period, vehicle miles of travel (VMT) has grown by 73.5 percent, and transit share for commuting has dropped from 10 to 6.3 percent. As a result, congestion has been steadily increas- ing. Currently, the region is served by two rail transit routes that do not constitute a regional sys- tem, and as a result leave holes in coverage and connectivity. The region continues to be designated a "severe" ozone non-attainment area. A substantial number of households remain in poverty, lacking appropriate skills for and access to employment. Action. Several strategies to deal with the economic development, poverty, mobility, and envi- ronmental issues are being attempted. Chief among these strategies are (1) a major new investment in rail transit and (2) stimulation of TOD around new and existing rail stations. In March 2002, a plan was adopted that lays out a system of rail transit routes to provide high quality transit acces- sibility to the entire region. One of the proposed lines, the "Red Line," runs through some of the city's most distressed neighborhoods on the west side. Opening the line would link the two exist- ing rail transit facilities into a regional system. The Baltimore Metropolitan Council (BMC) has taken steps to update and enhance its regional travel models to evaluate TOD scenarios that focus future growth around the proposed integrated transit network. BMC has conducted research on the transportation/land use connection which it hopes to incorporate in its forecasting for the Red Line as well as for related evaluations of alter- native land use concepts. Analysis. A primary goal of the Red Line project is to stimulate TOD around the proposed stations and have an effect not only on future ridership but also on community and economic development. For Baltimore, a successful strategy would hope to attract new households and jobs to the transit- served areas, which ideally would be households or jobs that might otherwise locate in the outer suburbs and contribute disproportionately to highway demand, congestion and air pollution. Previously, BMC was accounting for the effects of land use in its trip generation model by using a stratification based on residential density to differentiate trip generation rates among four settings: CBD, inner city, suburban, and rural. Household trip production rates (by household income and vehicle ownership) were developed for six different trip purposes: home-based work, home-based school, home-based shop, home-based other, non-home- based, and work-based other. Separate trip generation rates (tables) were developed for walk 17-121

OCR for page 121
trips. The 2001 regional household travel survey permitted analyses to be conducted to determine whether the existing process could be enhanced to provide a higher level of discernment among different land use contexts than simply using the four density-related area-type codes. Results. Initial analyses performed at an aggregate level on a selection of neighborhoods affirmed the apparent importance of density in explaining travel differences. A sub-sample of about 1,200 households from the 3,500-household 2001 travel survey was selected in a manner to define 32 dis- tinct "places" in the Baltimore region. Each place was subsequently analyzed as a distinct data point when comparing travel, demographic, and land use characteristics. Comparing the places based solely on residential density and daily vehicle miles of travel (DVMT) per capita (a primary measure of auto dependency) a fairly strong logarithmic relationship was indicated, as evidenced by an R-Squared of 0.727. The relationship is displayed in Figure 17-6. Figure 17-6 Daily per capita VMT by residential density While the displayed relationship was striking, BMC researchers recognized that residential den- sity alone was probably not the full story behind this relationship. First, factors like affluence (number of wage earners, income, and vehicle ownership) tend to follow spatial patterns, with more affluent households generally choosing to reside in lower density suburbs. Second, residen- tial density can often be a mask for other important land use characteristics, namely the mix and balance of different uses, the "design" by which these uses are connected in a pedestrian/transit friendly setting, and the degree of access to regional opportunities enabled by both regional loca- tion and transit and highway connectivity. 17-122

OCR for page 121
To understand the importance of these various influences, a disaggregate analysis was undertaken in which household travel activity was studied in simultaneous relationship to demographic char- acteristics, regional accessibility, and local land use. Several multiple regression models were developed to ascertain the statistical importance and relative contribution of these various factors to household travel, including a model of household DVMT and a model of household vehicle ownership. Table 17-55 presents these models. The regression analysis showed that the attributes of location--both regional accessibility and local land use context--have a profound bearing on household travel behavior. A special challenge was representing local land use characteristics. These characteristics are sufficiently fine-grained that they cannot be represented with conventional TAZ-level information. Instead, GIS procedures were developed to analyze parcel-level data and calculate a variety of measures reflecting mix, balance, dispersion, and walkability within 1/2 mile of the household. Measures of entropy (land use mix) and dissimilarity (balance) were developed using methods pioneered by Cervero and Kockelman. However, rather than use a subjective pedestrian/environmental friendliness- type measure to reflect selected land use characteristics, BMC created a measure of "local opportu- nities." This variable incorporated information on the classification and proximity of commercial activities within 1/2 mile of actual distance from the individual household as measured along the street network. Such "opportunities" would likely be greater for households in a TOD as compared to a non-TOD setting. 17-123

OCR for page 121
Table 17-55 BMC Multiple Regression Models for Predicting Daily Household (HH) DVMT and Vehicle Ownership HH DVMT HH Vehicles Model Model Variable Coefficients Coefficients Household Characteristics HH Members: Number of members in household. 2.33 0.535 HH Members Under Age 18: Number of members in -- -0.531 household younger than 18 years of age. HH Workers: Number of workers in household. 8.36 -- HH Vehicles: Number of vehicles owned by household. 8.38 -- HH Income: Annual income, coded in $5,000 increments. 1.38 0.069 Regional Accessibility Regional Jobs Accessibility: For each mode (auto and transit), calculate the number of jobs reachable, divided by the travel time to reach the opportunity (as determined by the regional -1.19E-04 -6.3E-06 gravity model). Sum figure for auto and transit. Coefficient is small because this sum is a relatively large number. Local Land Use Entropy: Measure of mix of different land uses within 1/2 mile of the household. To calculate, the area in the 1/2-mile buffer is divided into 49 separate hectares (2.5 acre -6.55 -0.471 grid cells) and one of seven primary land uses is assigned to each cell based on the dominant land use. Standard entropy formula is then applied. Log (Opportunities): Measure uses information on the location and SIC-code of commercial activities within 1/2 mile of the household. The shape of the street/road grid is used to determine proximity. Log transformation is used to moderate -1.84 -0.064 the effect of significant differences between sites with numerous "opportunities" versus sites with few proximate opportunities. Model Constant 12.75 0.634 R-Squared 0.405 0.526 Notes: Each model estimated with 2,707 degrees of freedom. All coefficients significant at the 99 percent confidence level. The coefficients in the model of household DVMT production have the expected sign and realistic magnitudes: household DVMT is predicted to increase with the number of members, number of workers, number of vehicles, and annual income, and to decrease with higher values of regional job accessibility, entropy, and local opportunities. In addition to the daily model, similar models were estimated for home-based work and non-work VMT, with the general difference being that the model for work travel showed the regional accessibility measure of land use to be important 17-124

OCR for page 121
to the exclusion of entropy and opportunities, while the non-work model found the local land use measures--entropy and opportunities--to be very important and regional accessibility less important. The household automobile ownership model also reflected the importance of land use factors. Vehicle ownership is predicted to increase with the number of members and annual income, but decrease with the number of household members younger than 18. Vehicle ownership is also predicted to decrease with higher values of regional job accessibility, entropy, and local opportu- nities. This is an important finding since it says that while income is an important factor, the regional and local land use characteristics also play significant roles in vehicle ownership decisions. Point elasticities for the coefficients in both the household DVMT and household vehicle owner- ship models are provided in Table 17-56. Point elasticity is calculated as the percent change in the dependent variable (HH DVMT or HH Vehicles) in response to a one percent change in the given independent variable (calculated in infinitesimally small increments).27 The results indicate that the key demographic variables--household size, workers, children, income--are the primary and most important determinants of DVMT and vehicle ownership, but the land use and accessibility variables also have a non-trivial impact. Of particular note is the role of the land use variables in not only influencing DVMT production directly, but also indirectly through vehicle ownership. More . . . BMC is now in the process of assessing how these findings can be used in ongoing model update and enhancement activities, particularly in developing ridership and travel forecasts for the Red Line. BMC is also contemplating using these findings in sketch planning tools to help local jurisdictions explore alternative land use plans and programs. 27 A negative sign indicates that the response operates in the opposite direction of the change in the variable, i.e., an increase in the value represented by the dependent variable results in a decrease in the value of the independent variable. For additional information on elasticity types, calculation, and application, see "Concept of Elasticity" in Chapter 1, "Introduction," and Appendix A, "Elasticity Discussion and Formulae." 17-125