Jeannette Montufar

Pedestrians' Normal Walking Speed and Speed When Crossing a Street

Walking speed is a key input for various traffic engineering applications. This paper presents the results of research conducted over 18 months to understand the difference between the normal and the crossing walking speeds of pedestrians at signalized intersections and to determine the effect of seasonality on walking speed, taking into account age and gender. For the purposes of this paper, normal walking speed is the speed at which pedestrians walk without needing to cross an intersection, and crossing walking speed is that at which pedestrians walk when they are crossing a signalized intersection. The research found that in all cases the normal walking speed is less than the crossing walking speed. It also found that younger pedestrians walk faster than older pedestrians, regardless of the season and gender, and females walk slower than males, regardless of the season and age. Furthermore, both younger and older pedestrians have a greater normal walking speed in summer than in winter but a lower crossing walking speed in winter than in summer. In addition, the research also found that by use of a design value of 1.2 m/s (4.0 ft/s), as recommended in the current Manual of Uniform Traffic Control Devices, nearly two-thirds of older pedestrians would be excluded in the design process on the basis of their normal walking speed and about 40% would be excluded on the basis of their crossing walking speed. The design value of 1.2 m/s (4.0 ft/s) excludes nearly one-third of younger pedestrians on the basis of their normal walking speed and about 10% on the basis of their crossing walking speed.

Walking Speed of Older Pedestrians who use Canes or Walkers for Mobility

Findings are presented of a follow-up study conducted in Winnipeg, Canada, to investigate the walking speed of older pedestrians who use walkers or canes for mobility. The results are from research conducted to understand the differences between the normal and the crossing walking speeds of older pedestrians who use walkers or canes for mobility at signalized intersections. This walking speed is also compared with that of older pedestrians who ambulate without assistive devices. For the purposes of this research, normal walking speed is the speed at which pedestrians walk without needing to cross any intersection, and crossing walking speed is that at which pedestrians walk when crossing a signalized intersection. The research found that in all cases the normal speed is lower than the crossing walking speed for older pedestrians with or without assistive devices. There are no seasonal differences in the normal walking speed of older pedestrians with walkers or canes. However, the crossing walking speed is higher in winter than in summer. Regarding gender issues, older men walk faster than older women when assistive devices are not used. However, there are no gender differences in walking speed when pedestrians use walkers or canes for mobility. Although this research shows that using the current walking-speed assumption of 1.2 m/s (4.0 ft/s), as recommended in the U.S. Manual on Uniform Traffic Control Devices, almost all older pedestrians needing walkers or canes for mobility would be excluded in the design process, it also shows other information that would be valuable for improved urban planning, transit operations, and other transportation engineering applications.

Safety performance of longer combination vehicles relative to other articulated trucks

This article helps improve the understanding about the safety performance of longer combination vehicles (LCVs) relative to other articulated trucks operating on rural highways, using evidence from the Canadian portion of the CANAMEX trade corridor. The analysis reveals that from a collision rate perspective, LCVs as a group have better safety performance than other articulated trucks. Turnpike doubles have the lowest collision rate of all articulated truck types (16 collisions per 100 million vehicle-kilometres of travel or VKT), followed by Rocky Mountain doubles (32 collisions per 100 million VKT). The collision rate for triple trailer combinations (62 collisions per 100 million VKT) is higher than the collision rates for tractor semitrailers (42 collisions per 100 million VKT) and legal-length tractor double trailers (44 collisions per 100 million VKT). These results are an important input for civil engineering and transport policy decisions concerning longer combination vehicle operations.

Value of a statistical life in road safety: a benefit-transfer function with risk-analysis guidance based on developing country data

We model a value of statistical life (VSL) transfer function for application to road-safety engineering in developing countries through an income-disaggregated meta-analysis of scope-sensitive stated preference VSL data. The income-disaggregated meta-analysis treats developing country and high-income country data separately. Previous transfer functions are based on aggregated datasets that are composed largely of data from high-income countries. Recent evidence, particularly with respect to the income elasticity of VSL, suggests that the aggregate approach is deficient because it does not account for a possible change in income elasticity across income levels. Our dataset (a minor update of the OECD database published in 2012) includes 123 scope-sensitive VSL estimates from developing countries and 185 scope-sensitive estimates from high-income countries. The transfer function for developing countries gives VSL=1.3732E-4×(GDP per capita)(∧)2.478, with VSL and GDP per capita expressed in 2005 international dollars (an international dollar being a notional currency with the same purchasing power as the U.S. dollar). The function can be applied for low- and middle-income countries with GDPs per capita above

Performance measures and input uncertainty for pedestrian crossing exposure estimates

1268 (with a data gap for very low-income countries), whereas it is not useful above a GDP per capita of about

OPERATION OF LONG SEMITRAILERS IN THE UNITED STATES

20,000. The corresponding function built using high-income country data is VSL=8.2474E+3×(GDP per capita)(∧).6932; it is valid for high-income countries but over-estimates VSL for low- and middle-income countries. The research finds two principal significant differences between the transfer functions modeled using developing-country and high-income-country data, supporting the disaggregated approach. The first of these differences relates to between-country VSL income elasticity, which is 2.478 for the developing country function and .693 for the high-income function; the difference is significant at p<0.001. This difference was recently postulated but not analyzed by other researchers. The second difference is that the traffic-risk context affects VSL negatively in developing countries and positively in high-income countries. The research quantifies uncertainty in the transfer function using parameters of the non-absolute distribution of relative transfer errors. The low- and middle-income function is unbiased, with a median relative transfer error of -.05 (95% CI: -.15 to .03), a 25th percentile error of -.22 (95% CI: -.29 to -.19), and a 75th percentile error of .20 (95% CI: .14 to .30). The quantified uncertainty characteristics support evidence-based approaches to sensitivity analysis and probabilistic risk analysis of economic performance measures for road-safety investments.

Data Collection Methodology for Container Truck Traffic in Inland Port Cities

Pedestrian safety performance measures often use estimates of annual crossing exposure as inputs-but relatively little information exists on the uncertainty associated with these inputs. This research considers two sources of temporal information for expanding short-term counts: (1) a composite of pedestrian counts from other cities, and (2) local vehicle counts. A database of pedestrian flows from video review covering 12 months and including over 350,000 pedestrian observations provides a known reference annual volume and a set of short-term counts for expansion and testing. The research compares the temporal information sources with observed pedestrian volumes by analyzing the times and magnitudes of volume peaks. The temporal patterns based on local vehicle counts match observed pedestrian patterns more closely than the external composite pedestrian patterns. To quantify exposure estimate uncertainty, the research uses the local vehicle and external composite pedestrian patterns to expand a sample of short term counts to generate a set of 200 annual estimates, and then compares the estimates to the known reference volume. Exposure estimates developed by expanding counts with local vehicle factors have the lowest errors (mean: -2%; median: -3%, standard deviation: 33%; 90 percent of errors between -53% and 50%). Exposure estimates based on external composite pedestrian patterns have higher errors (mean: 27%; median: 9%; standard deviation: 73%; 90 percent of errors between -62% and 170%). If methods to obtain pedestrian exposure estimates based on short-term counts are improved, more confidence can be placed in safety performance measures that use these estimates as inputs.

Field evaluation of automatic pedestrian detectors in cold temperatures

The regulation and use of long semitrailers (57 to 60 ft) in the United States are discussed. Industrial information was obtained from interviewing 42 state and federal regulatory and compliance officials, vehicle manufacturers, motor carriers, and shippers. Field data from a June 2002 investigation of long semitrailer use on an Interstate highway section in Texas are presented. No known significant literature exists on the topic under discussion. The research found that long semitrailers operate, either regularly or under permit, in 19 states. They are principally used by a few large private and for-hire carriers, transporting mainly tissue paper, empty cans, hay, cotton, empty storage container drums, household goods, snack foods, and general freight. The extent of their operation is largely unknown or unclear to many of those involved with truck size and weight research and development activities, highway planners and designers, and industry participants. The following are addressed: (a) issues about long semitrailer operation in the United States and the growth potential of these vehicles relative to the TRB Special Report 267 proposal to allow wide-scale use of six-axle tractor-semitrailers at a gross vehicle weight of 90,000 Ib; (b) background on using long semitrailers; (c) operational issues associated with long semitrailers; (d) typical dimensional characteristics and cubic payloads of long semitrailers compared with standard semitrailers; (e) field data on the use of long semitrailers in Texas; and (f) regulations, permit requirements, and allowable geographic scope of operation for long semitrailers.

Using Intelligent Transportation Systems to Adapt to Potential Climate Change Impacts on Seasonal Truck Weight Limits

This paper describes a data collection methodology to address insufficient data sources for estimation of urban container truck traffic (drayage) volumes. The methodology is sensitive to the characteristics of drayage and offers a systematic approach for acquiring container truck traffic data for constructing models to estimate drayage volumes. The methodology consists of (a) acquiring urban truck traffic estimates and national and provincial- or state-level container traffic databases, (b) characterizing shippers and carriers through field investigations and surveys, and (c) designing a container truck data collection program. Short-term manual truck classification intersection turning movement counts were conducted to obtain body style and axle configuration data for articulated trucks. Temporal expansion factors were developed and applied to short-term count data to produce average daily container truck traffic volume estimates and reveal temporal, physical, and spatial distribution differences between container trucks and other articulated trucks. The paper provides a rationale for selecting count station locations and their temporal characteristics, choosing the number of counts and their duration, determining the types of data to collect, and identifying container generators. The methodology is generally applicable to North American inland port cities. The data feed a model that is intended to assist transportation engineers in understanding urban drayage operations and quantifying the exposure of these trucks.

TECHNIQUES FOR BUILDING MULTIJURISDICTIONAL GEOGRAPHIC INFORMATION SYSTEM PLATFORMS FOR TRANSPORTATION ANALYSIS

The equitable accommodation of pedestrians is critical in transportation engineering and planning. Major concerns over the use of push buttons to activate pedestrian signals have been raised in many jurisdictions because elderly pedestrians and certain physically impaired pedestrians experience difficulty using push buttons, even when the push button is placed in a convenient and standard location. This paper presents the results of an analysis of the performance of three commercially available curbside automatic pedestrian detectors (APD)—a passive infrared and stereovision curbside detector, a passive infrared curbside detector, and a microwave detector—in the field as a function of weather, temperature, and temporal variations at signalized intersections during the winter months at temperatures ranging from −34°C (−29°F) to 0°C (32°F). The results were classified according to detector sensitivity, which referred to the percentage of pedestrian crossings detected successfully, and detector selectivity, which referred to the percentage of activations triggered by actual pedestrians, instead of false activations from vehicle movement, trees in the wind, or other causes. From a sample of 8,225 detections at two sites, the results revealed that the three APDs were generally sensitive at sending valid pedestrian calls, but selectivity rates remained less than 50%. Under all conditions and of all APDs analyzed, the infrared detector consistently had the highest sensitivity and lowest selectivity; the infrared–video detector had the second-highest sensitivity and the highest selectivity; and the microwave detector had the lowest sensitivity and the second-highest selectivity.