Rodríguez-Selected Publications

Rodríguez, D.A., Targa, F. and Aytur, S. In press. Transportation implications of urban
containment policies --A study of the largest 25 U.S. metropolitan areas, Urban Studies,
40 pages.

Urban containment policies attempt to manage the location and character of growth to support a
variety of community goals. Despite earlier attempts to evaluate the consequences of containment policy
adoption, the transportation implications of these policies have been overlooked. In this paper we examine
the impact that containment policies have on population density and vehicle miles traveled per capita.
First, we review theory and prior evidence to conclude that the transportation impacts of containment
policies are unclear. Second, we conduct an empirical analysis of the effects of containment policies
on density and travel by relying on a fixed-effects model for panel data for the largest 25 metropolitan
areas in the U.S. during the 1982-1994 time-period. Because the outcomes are endogenously related,
we use instrumental variable regression to test hypotheses about the effect of the presence and age
of containment policies on the outcomes. The findings suggest that local containment policies and
state-level involvement in enabling or mandating growth management are associated with higher
population density and more miles traveled. We also find that the time since the adoption of the
containment policies matters, but at a decreasing rate. The results uncover unanticipated relationships
of containment policies and travel outcomes, and underscore the importance of a coordinated strategy
to mitigate some of the potential travel consequences of containment policies.

Armstrong, R. and Rodríguez, D. (In press) An Evaluation of the Accessibility Benefits of
Commuter Rail in Eastern Massachusetts Using Spatial Hedonic Price Functions.   Accepted
for publication with minor reviews on 07/11/2004, Transportation 36pp.

We estimate spatial hedonic price functions to examine local and regional accessibility benefits of
commuter rail service in Eastern Massachusetts, while controlling for proximity-related negative
externalities and other confounding influences. The data include 2,772 single-family residential
properties from four municipalities with commuter rail service, and three municipalities without
commuter rail service. We find some evidence of the capitalization of accessibility to commuter rail
stations. Properties located in municipalities with commuter rail stations exhibit values that are
between 15.7 percent and 29.6 percent higher than properties in municipalities without a commuter
rail station. By contrast, we detect no evidence of the capitalization of auto access time or walking
time to the stations, or of the regional accessibility benefits of commuter rail. Our results also indicate
that proximity to commuter rail right-of-way has a significant negative effect on property values, which
suggests that for every 1,000 ft. in distance from the commuter rail right-of-way, property values are
$1,500 higher, all else held equal. At the mean sample values, this result translates into an elasticity
of between 0.07 and 0.18, depending on the functional form of the hedonic price equation.

Rodríguez, D., Khattak, A., and Evenson, K.J. (in press) Can New Urbanism encourage physical
activity?  Physical activity in a new urbanist and conventional suburban neighborhoods.
Accepted for publication on 11/20/2004, Journal of the American Planning Association, 30 pp.

If neighborhood design can support or impede active lifestyles, we hypothesize that residents of new
urbanist neighborhoods will exhibit higher levels of physical activity than residents of conventional
communities. This study evaluates physical activity patterns of residents in distinctly different neighborhoods:
a new urbanist neighborhood and a group of conventional suburban neighborhoods in central North Carolina.
We found no statistically significant differences in various measures of physical activity of household heads
between the two neighborhoods, even after adjusting for individual and household characteristics. However,
we detected differences in where people were physically active. New urbanist residents were more likely to
be physically active in their neighborhood than conventional suburban residents, suggesting a substitutive
behavior between the places where physical activity can occur. Walking for utilitarian purposes, rather than
for leisure, in the new urbanist neighborhood was the source of this difference. This indicates that new
urbanist neighborhood residents were able to incorporate physical activity into their daily routine of accessing
destinations in their neighborhood. Despite the usual limitations of using a quasi-experimental research
design, our results underscore the complexity of understanding the determinants of physical activity and
raise doubts regarding new urbanism's ability to promote higher levels of total physical activity among
its residents.

Rodríguez, D., Targa, F. and M. Belzer (In press) Pay Incentives and Truck Driver Safety:
A Case Study. Accepted for publication with minor reviews on 07/15/2004, Industrial and
Labor Relations Review 45pp.

This paper provides an empirical examination of the safety consequences of increasing truck driver
pay by estimating discrete duration models of driver separation-from-the firm and driver crash
probability using data from a large-over-the road truckload firm that on February 25, 1997 raised wages
an average of 39.1%. A two-stage approach allows the isolation of the direct influence of
demographic, pay, and operational factors on crash probability from their indirect effect through the
probability of leaving the firm. Results suggest that, for drivers who were employed during the lower
pay regime and retained in the higher pay regime, the increase in pay resulted in better crash records,
controlling for demographic and operational factors, including prior driving experience and experience
acquired on the job. A higher pay rate also led to lower separation probability, but this indirect effect
only translated into fewer crashes by increasing the retention of older, more experienced drivers.
To the extent that generalizations about the truckload sector can be made from this study, our findings
suggest that human capital characteristics are important predictors of driver safety, but that
motivational and incentive factors also play an important role in determining the safety outcomes of
truck drivers.

Rodríguez, D.A., Brown, A. and Troped, P. 2005. Portable Global Positioning Units to Complement
Accelerometry-Based Physical Activity Monitors.   Accepted for publication on 06/12/2005, Medicine
and Science in Sports and Exercise, 37:11, S572-S581.

Purpose: This study examines the usefulness of complementing accelerometry-based physical activity
measurement with spatial data from portable global positioning system (GPS) units to determine where
physical activity occurs.
Methods: First, using the geographic distribution of data points and Bland–Altman plots, we examined GPS
units’ validity and interunit reliability by measuring the distance to a geodetic point. We also assessed interunit
reliability by comparing GPS data collected in three built environment contexts. Second, we conducted a pilot
study in which 35 participants wore GPS units and accelerometers in free-living conditions for 3 d. Moderate
and vigorous physical activity (MVPA) bouts were matched to GPS data. We classified each bout as occurring
inside or outside the participant’s home neighborhood. Using unpaired t-tests and Fisher’s exact tests, we
compared neighborhood attributes for participants having the majority of MVPA bouts within their home
neighborhood, relative to those with most bouts away from their home neighborhood.
Results: Average distance from each unit to the geodetic point was 3.02 m (SD 2.51). Average bias among
units using Bland–Altman plots was 0.90 m, ranging from _0.22 to 1.86 m, within the limits of agreement.
For interunit reliability in the built environment contexts, the mean distance difference among units ranged
between 10.7 m (SD 11.9) and 20.1 m (SD 21.8). For the pilot study involving participants, GPS data were
available for 59.3% of all bouts (67% of MVPA time), of which 46% were in the participants’ neighborhood.
Participants obtaining most of their MVPA in their neighborhoods tend to live in areas with higher population
density, housing unit density, street connectivity, and more public parks.
Conclusion: Data recorded by portable GPS units is sufficiently precise to track participants’ movements.
Successful matching of activity monitor and locational data suggests GPS is a promising tool for
complementing accelerometry-based physical activity measures. Our pilot analysis shows evidence that
the relationship between environment and activity can be clarified by examining where physical activity
occurs.

Rodríguez, D. and Targa, F. (In press) The value of accessibility to Bogotá’s bus rapid transit
system, Transport Reviews, accepted for publication on 12/09/2003 40 pp.

With several successful cases worldwide, bus rapid transit (BRT) has re-emerged as a cost-effective
transportation alternative for providing urban mobility. Despite the resurgence of BRT, there is a
worldwide paucity of research examining its ability to spur land development. By estimating spatial
hedonic price functions, this paper determines the extent to which access to BRT stations in Bogotá,
Colombia currently are capitalized into land values. Results suggest that for every 5 minutes of
additional walking time to a BRT station, the rental price of a property decreases between 6.8% and
9.3%, after controlling for structural characteristics, neighborhood attributes, and proximity to the BRT
corridor. Evaluated at the average walking time to a BRT station, this effect translates into an
elasticity of between -0.16 and -0.22. Although these estimates cannot be attributable directly to the
presence of the BRT system because we use a cross-sectional design, they suggest that the land
market in Bogotá values access to BRT station locations.


	RELATED LINKS: Rodríguez Home Summary of Existiong Projects Ongoing & Recently Completed Research Support Additional Abstracts		Rodríguez, D.A., Targa, F. and Aytur, S. In press. Transportation implications of urban containment policies --A study of the largest 25 U.S. metropolitan areas, Urban Studies, 40 pages. Urban containment policies attempt to manage the location and character of growth to support a variety of community goals. Despite earlier attempts to evaluate the consequences of containment policy adoption, the transportation implications of these policies have been overlooked. In this paper we examine the impact that containment policies have on population density and vehicle miles traveled per capita. First, we review theory and prior evidence to conclude that the transportation impacts of containment policies are unclear. Second, we conduct an empirical analysis of the effects of containment policies on density and travel by relying on a fixed-effects model for panel data for the largest 25 metropolitan areas in the U.S. during the 1982-1994 time-period. Because the outcomes are endogenously related, we use instrumental variable regression to test hypotheses about the effect of the presence and age of containment policies on the outcomes. The findings suggest that local containment policies and state-level involvement in enabling or mandating growth management are associated with higher population density and more miles traveled. We also find that the time since the adoption of the containment policies matters, but at a decreasing rate. The results uncover unanticipated relationships of containment policies and travel outcomes, and underscore the importance of a coordinated strategy to mitigate some of the potential travel consequences of containment policies. Armstrong, R. and Rodríguez, D. (In press) An Evaluation of the Accessibility Benefits of Commuter Rail in Eastern Massachusetts Using Spatial Hedonic Price Functions. Accepted for publication with minor reviews on 07/11/2004, Transportation 36pp. We estimate spatial hedonic price functions to examine local and regional accessibility benefits of commuter rail service in Eastern Massachusetts, while controlling for proximity-related negative externalities and other confounding influences. The data include 2,772 single-family residential properties from four municipalities with commuter rail service, and three municipalities without commuter rail service. We find some evidence of the capitalization of accessibility to commuter rail stations. Properties located in municipalities with commuter rail stations exhibit values that are between 15.7 percent and 29.6 percent higher than properties in municipalities without a commuter rail station. By contrast, we detect no evidence of the capitalization of auto access time or walking time to the stations, or of the regional accessibility benefits of commuter rail. Our results also indicate that proximity to commuter rail right-of-way has a significant negative effect on property values, which suggests that for every 1,000 ft. in distance from the commuter rail right-of-way, property values are $1,500 higher, all else held equal. At the mean sample values, this result translates into an elasticity of between 0.07 and 0.18, depending on the functional form of the hedonic price equation. Rodríguez, D., Khattak, A., and Evenson, K.J. (in press) Can New Urbanism encourage physical activity? Physical activity in a new urbanist and conventional suburban neighborhoods. Accepted for publication on 11/20/2004, Journal of the American Planning Association, 30 pp. If neighborhood design can support or impede active lifestyles, we hypothesize that residents of new urbanist neighborhoods will exhibit higher levels of physical activity than residents of conventional communities. This study evaluates physical activity patterns of residents in distinctly different neighborhoods: a new urbanist neighborhood and a group of conventional suburban neighborhoods in central North Carolina. We found no statistically significant differences in various measures of physical activity of household heads between the two neighborhoods, even after adjusting for individual and household characteristics. However, we detected differences in where people were physically active. New urbanist residents were more likely to be physically active in their neighborhood than conventional suburban residents, suggesting a substitutive behavior between the places where physical activity can occur. Walking for utilitarian purposes, rather than for leisure, in the new urbanist neighborhood was the source of this difference. This indicates that new urbanist neighborhood residents were able to incorporate physical activity into their daily routine of accessing destinations in their neighborhood. Despite the usual limitations of using a quasi-experimental research design, our results underscore the complexity of understanding the determinants of physical activity and raise doubts regarding new urbanism's ability to promote higher levels of total physical activity among its residents. Rodríguez, D., Targa, F. and M. Belzer (In press) Pay Incentives and Truck Driver Safety: A Case Study. Accepted for publication with minor reviews on 07/15/2004, Industrial and Labor Relations Review 45pp. This paper provides an empirical examination of the safety consequences of increasing truck driver pay by estimating discrete duration models of driver separation-from-the firm and driver crash probability using data from a large-over-the road truckload firm that on February 25, 1997 raised wages an average of 39.1%. A two-stage approach allows the isolation of the direct influence of demographic, pay, and operational factors on crash probability from their indirect effect through the probability of leaving the firm. Results suggest that, for drivers who were employed during the lower pay regime and retained in the higher pay regime, the increase in pay resulted in better crash records, controlling for demographic and operational factors, including prior driving experience and experience acquired on the job. A higher pay rate also led to lower separation probability, but this indirect effect only translated into fewer crashes by increasing the retention of older, more experienced drivers. To the extent that generalizations about the truckload sector can be made from this study, our findings suggest that human capital characteristics are important predictors of driver safety, but that motivational and incentive factors also play an important role in determining the safety outcomes of truck drivers. Rodríguez, D.A., Brown, A. and Troped, P. 2005. Portable Global Positioning Units to Complement Accelerometry-Based Physical Activity Monitors. Accepted for publication on 06/12/2005, Medicine and Science in Sports and Exercise, 37:11, S572-S581. Purpose: This study examines the usefulness of complementing accelerometry-based physical activity measurement with spatial data from portable global positioning system (GPS) units to determine where physical activity occurs. Methods: First, using the geographic distribution of data points and Bland–Altman plots, we examined GPS units’ validity and interunit reliability by measuring the distance to a geodetic point. We also assessed interunit reliability by comparing GPS data collected in three built environment contexts. Second, we conducted a pilot study in which 35 participants wore GPS units and accelerometers in free-living conditions for 3 d. Moderate and vigorous physical activity (MVPA) bouts were matched to GPS data. We classified each bout as occurring inside or outside the participant’s home neighborhood. Using unpaired t-tests and Fisher’s exact tests, we compared neighborhood attributes for participants having the majority of MVPA bouts within their home neighborhood, relative to those with most bouts away from their home neighborhood. Results: Average distance from each unit to the geodetic point was 3.02 m (SD 2.51). Average bias among units using Bland–Altman plots was 0.90 m, ranging from _0.22 to 1.86 m, within the limits of agreement. For interunit reliability in the built environment contexts, the mean distance difference among units ranged between 10.7 m (SD 11.9) and 20.1 m (SD 21.8). For the pilot study involving participants, GPS data were available for 59.3% of all bouts (67% of MVPA time), of which 46% were in the participants’ neighborhood. Participants obtaining most of their MVPA in their neighborhoods tend to live in areas with higher population density, housing unit density, street connectivity, and more public parks. Conclusion: Data recorded by portable GPS units is sufficiently precise to track participants’ movements. Successful matching of activity monitor and locational data suggests GPS is a promising tool for complementing accelerometry-based physical activity measures. Our pilot analysis shows evidence that the relationship between environment and activity can be clarified by examining where physical activity occurs. Rodríguez, D. and Targa, F. (In press) The value of accessibility to Bogotá’s bus rapid transit system, Transport Reviews, accepted for publication on 12/09/2003 40 pp. With several successful cases worldwide, bus rapid transit (BRT) has re-emerged as a cost-effective transportation alternative for providing urban mobility. Despite the resurgence of BRT, there is a worldwide paucity of research examining its ability to spur land development. By estimating spatial hedonic price functions, this paper determines the extent to which access to BRT stations in Bogotá, Colombia currently are capitalized into land values. Results suggest that for every 5 minutes of additional walking time to a BRT station, the rental price of a property decreases between 6.8% and 9.3%, after controlling for structural characteristics, neighborhood attributes, and proximity to the BRT corridor. Evaluated at the average walking time to a BRT station, this effect translates into an elasticity of between -0.16 and -0.22. Although these estimates cannot be attributable directly to the presence of the BRT system because we use a cross-sectional design, they suggest that the land market in Bogotá values access to BRT station locations.