Pettebone D.,Colorado State University |
Newman P.,Colorado State University |
Lawson S.R.,Resource Systems Group Inc.
Landscape and Urban Planning | Year: 2010
Data on visitor use are essential to the planning and management of National Park units in order to assess visitor impacts to the resource, estimate the quality of the visitor experience, and to inform facilities planning. Recently, automated infrared monitors have become a popular tool to estimate visitor-use levels at attraction sites and along trails in national parks and related protected natural areas. However, there are counting errors associated with all automated counters, thus procedures are required to convert raw counter data to accurate estimates of recreational use. The purpose of this study was to assess the performance (i.e., degree of error) of automated trail traffic counters and document procedures to correct counting errors associated with their use to measure visitor use. This study was conducted in Yosemite National Park in the summer of 2007 and used automated visitor counters to estimate visitor use at attraction sites and trailheads in Yosemite Valley. A total of 135h of direct observation counts were conducted in tandem with the use of automated counters at six study sites to estimate counting errors in the automated counter data. A series of statistical procedures was used to calibrate raw monitor data to accurate estimates of visitor use at each of the study sites. Results of the study suggest there is a strong statistical relationship between observation-based visitor counts and monitor counts (R2>0.95), which supports confidence in the use of monitors to estimate recreational use in national parks and protected natural areas. © 2010.
D'Antonio A.,Utah State University |
Monz C.,Utah State University |
Newman P.,Colorado State University |
Taff D.,Colorado State University |
Lawson S.,Resource Systems Group Inc.
Environmental Management | Year: 2012
An on-site visitor survey instrument was developed to examine visitor perceptions of resource impacts resulting from backcountry hiking activities. The survey was conducted in the Bear Lake Corridor of Rocky Mountain National Park, CO and examined visitor characteristics that may influence visitor perceptions of specific resource conditions. Findings indicate that visitors are more perceptive of recreation-related resource impacts that are the result of undesirable behavior and, while visitors do perceive resource impacts, visitors tend to be more affected by crowding. Factors such as local ecological knowledge and knowledge of minimal-impact practices positively influence visitor perceptions of resource impacts. These findings support the use of visitor education on ecological knowledge and minimum-impact as a means of increasing visitor awareness of recreation impact issues. © Springer Science+Business Media, LLC 2012.
Sikka N.,Resource Systems Group Inc. |
Hanley P.,University of Iowa
Transportation | Year: 2013
The measurement of transportation system reliability has become one of the central topics of travel demand studies. A growing literature concerns the measurement of value of travel time reliability which provides a monetary cost of avoiding unpredictable travel time. The goal of this study is to measure commuters' sensitivities to travel time reliability and their willingness to pay (WTP) to avoid unreliable routes. The preferences are elicited through a pivoted stated preference survey technique. To circumvent the issue of presenting numerical distributions and statistical terms to day-to-day commuters, we use the frequency of delay days as a means of measuring traveler's sensitivities to travel time reliability. The advantage of using simplified measures to elicit traveler preferences for travel time reliability is that these methods simply compare days with high delay to days with usual travel time. It was found that travelers are not only averse to the amount of unexpected delay but also to the frequency of days with unexpected delays. The paper presents WTP findings for three measures: travel time, frequency embedded travel time, and travel time reliability. The 'reliability' increase in WTP for travel time is found to be nearly proportional to the frequency of experiencing unexpected delays. For example, the WTP for mean travel time is calculated at $6.98/h; however, reliability adds $3.27 (about 50 % of $6.98) to avoid unexpected delays '5 out of 10 days'. The results of the study would provide valuable inputs to cost-benefit analyses and traffic and revenue studies required for road tolling investment projects. © 2012 Springer Science+Business Media New York.
Ferdous N.,Resource Systems Group Inc. |
Bhat C.R.,University of Texas at Austin
Journal of Geographical Systems | Year: 2013
This paper proposes and estimates a spatial panel ordered-response probit model with temporal autoregressive error terms to analyze changes in urban land development intensity levels over time. Such a model structure maintains a close linkage between the land owner's decision (unobserved to the analyst) and the land development intensity level (observed by the analyst) and accommodates spatial interactions between land owners that lead to spatial spillover effects. In addition, the model structure incorporates spatial heterogeneity as well as spatial heteroscedasticity. The resulting model is estimated using a composite marginal likelihood (CML) approach that does not require any simulation machinery and that can be applied to data sets of any size. A simulation exercise indicates that the CML approach recovers the model parameters very well, even in the presence of high spatial and temporal dependence. In addition, the simulation results demonstrate that ignoring spatial dependency and spatial heterogeneity when both are actually present will lead to bias in parameter estimation. A demonstration exercise applies the proposed model to examine urban land development intensity levels using parcel-level data from Austin, Texas. © 2012 Springer-Verlag.
Hess S.,University of Leeds |
Adler T.,Resource Systems Group Inc.
Journal of Air Transport Management | Year: 2011
A growing number of studies of air travel behaviour make use of data collected through stated choice surveys. However, while these studies all produce useful results in their own right, they are limited to the context of each specific study. We address this issue by using data from four related surveys carried out between 2000 and 2005. The analysis shows a level of consistency in some of the sensitivities, but also highlights trends such as reduced willingness-to-pay measures, potentially influenced by the growing number of low cost flight options, lack of service differentiation among the carriers, and increased use of online ticketing, which has led to greater fare transparency. © 2010 Elsevier Ltd.
Hess S.,University of Leeds |
Ryley T.,Loughborough University |
Davison L.,Loughborough University |
Adler T.,Resource Systems Group Inc
Transportmetrica A: Transport Science | Year: 2013
Airport choice models have been used extensively in recent years to assist the transport planning in large metropolitan areas. However, these studies have typically focussed solely on airports within a given metropolitan area, at a time when passengers are increasingly willing to travel further to access airports. This article presents the findings of a study that uses broader, regional data from the East Coast of the United States collected through a stated choice based air travel survey. The study makes use of a cross-nested logit structure that allows for the joint representation of inter-alternative correlation along the three choice dimensions of airport, airline and access mode choice. The analysis not only shows significant gains in model fit when moving to this more advanced nesting structure, but the more appropriate cross-elasticity assumptions also lead to more intuitively correct substitution patterns in forecasting examples. © 2013 Copyright Hong Kong Society for Transportation Studies Limited.
Smith C.,Resource Systems Group Inc. |
Spitz G.,Resource Systems Group Inc.
Transportation Research Record | Year: 2010
Travel surveys can reach potential survey respondents in many ways, including intercepting them at activity centers or on transit vehicles and contacting them by telephone, mail, or online. The selection of a survey recruitment approach should consider whether the population from which a sample is drawn is fully covered in order to avoid coverage error. This paper presents two case studies that review data collected in travel surveys in metropolitan areas in the United States to identify coverage error, specifically whether lack of Internet access by a segment of the population leads to coverage error. The first case study analyzes data from several road pricing surveys to quantify differences between those who have and do not have Internet access. The second case study analyzes data from two transit origin-destination surveys in which respondents were invited to provide contact details for additional market research. This paper compares the overall sample with those willing to be surveyed in the future by telephone and those willing to receive a future survey invitation by e-mail. Both case studies find that the samples with access to the Internet are similar to the larger full samples that include those without Internet access and therefore that the coverage error found in the Internet-only samples is small. The results suggest that, for surveys of general populations of drivers or transit riders, surveying only those with Internet access does not introduce significant coverage error into travel survey samples.
Kaliski K.,Resource Systems Group Inc. |
Duncan E.,Resource Systems Group Inc.
Proceedings of Meetings on Acoustics | Year: 2010
Modeling done for wind farms usually focuses on calculating a worst-case short term average sound level. However, the impact to homes is not simply defined by a single meteorological condition. Rather, a more complete picture of the impacts is given by calculating sound levels under various meteorological conditions that occur during the year. The actual sound level at a receiver will depend on variations in atmospheric stability, wind speed, wind direction, and other parameters that change hourly. This paper will describe a method to calculate hourly sound pressure levels for individual receivers over the course of an 8760 h year and give examples of different wind farm configurations and how they affect annualized sound levels. © 2010 Acoustical Society of America.
Coogan P.F.,Boston University |
White L.F.,Boston University |
Evans S.R.,Boston University |
Adler T.J.,Resource Systems Group Inc. |
And 3 more authors.
American Journal of Preventive Medicine | Year: 2011
Background: Numerous cross-sectional studies have found higher levels of obesity among residents of auto-oriented, sprawling areas compared to residents of more urban areas. Purpose: The association between neighborhood urban form and 6-year weight change was prospectively analyzed in the Black Women's Health Study, a cohort study of U.S. black women who enrolled in 1995 and are followed biennially with mailed questionnaires. Methods: The analysis included 17,968 women who lived in New York City, Chicago, or Los Angeles and were followed from 1995 to 2001. Factor analysis was used to combine variables describing the urban form of participants' residential neighborhoods into an "urbanicity" score. Mixed linear regression models were used to calculate least-squares means for weight change across quintiles of the urbanicity score. Incidence rate ratios (IRRs) and 95% CIs for incident obesity in relation to the urbanicity score among women who were not obese at baseline were derived from Cox regression models. All results were adjusted for age, region, lifestyle factors, and neighborhood SES. Analyses were conducted in 2008-2010. Results: In multivariate analysis, mean weight gain for women in the highest quintile of urbanicity score (most urban) was 0.79 kg less than for those in the lowest quintile, with a significant trend (p=0.003). The IRR for incident obesity in the highest quintile relative to the lowest was 0.83 (95% CI=0.71, 0.97), with a significant trend (p=0.042). Conclusions: Policies that encourage dense, urban residential development may have a positive role to play in addressing obesity in black women. © 2011 American Journal of Preventive Medicine.
Broach J.,Portland State University |
Dill J.,Portland State University |
Gliebe J.,Resource Systems Group Inc.
Transportation Research Part A: Policy and Practice | Year: 2012
To better understand bicyclists' preferences for facility types, GPS units were used to observe the behavior of 164 cyclists in Portland, Oregon, USA for several days each. Trip purpose and several other trip-level variables recorded by the cyclists, and the resulting trips were coded to a highly detailed bicycle network. The authors used the 1449 non-exercise, utilitarian trips to estimate a bicycle route choice model. The model used a choice set generation algorithm based on multiple permutations of path attributes and was formulated to account for overlapping route alternatives. The findings suggest that cyclists are sensitive to the effects of distance, turn frequency, slope, intersection control (e.g. presence or absence of traffic signals), and traffic volumes. In addition, cyclists appear to place relatively high value on off-street bike paths, enhanced neighborhood bikeways with traffic calming features (aka " bicycle boulevards"), and bridge facilities. Bike lanes more or less exactly offset the negative effects of adjacent traffic, but were no more or less attractive than a basic low traffic volume street. Finally, route preferences differ between commute and other utilitarian trips; cyclists were more sensitive to distance and less sensitive to other infrastructure characteristics for commute trips. © 2012 Elsevier Ltd.