Pedestrian Delay Research Articles

Renovation scheduling to minimize user impact of a building that remains in operation

Abstract When renovating a building that remains in operation, the closure of some areas is inevitable. If a corridor needs to be closed off, the accessibility of rooms may be affected. To minimize the numbers of rooms that need to be closed, contractors usually construct temporary passageways. Because temporary passageways are narrow, they often have a user impact, including time delay. This impact needs to be quantified and improved through work zone scheduling. This paper proposed an integrated model that calculates the amount of pedestrian time delay through simulation and searches for the near-optimal schedule using ant colony optimization. The model is applied to the scheduling of a floor tile renovation project of a building that remains in operation. The finding indicates that the model reduces the pedestrian time delay to a much greater extent compared to the schedule proposed by human planners based on the location sequence of work zones.

Integrated Benefit Evaluation of Pedestrian Bridge

Pedestrian bridges can not only allow traffic to run more smoothly but also reduce vehicle fuel consumption and emission exhaust. Taking various factors into account is essential when making a benefit assessment for a pedestrian bridge. This paper establishes an integrated benefit evaluation method for pedestrian bridges. Factors that influence integrated benefits are classified into four categories: traffic, environment, resource, and maintenance. According to these factors, five evaluation indexes, which include vehicle delay profit and loss value (PLV), pedestrian delay PLV, exhaust emission PLV, fuel consumption PLV, and greening maintenance cost, were introduced into the benefits evaluation. Three methods were used to obtain these factors: traffic simulation, a mathematical model, and empirical values. Finally, an example is demonstrated to verify this method, and the results show that the method is reliable in practice.

Multiobjective Optimization of Signal Timings for Two-Stage, Midblock Pedestrian Crosswalk

To improve convenience and safety for pedestrians, signalized two-stage, midblock pedestrian crosswalks are increasingly being installed in highly populated areas in developing countries such as China. This paper presents a multiobjective optimization model and its solution algorithm for optimal control of a two-stage, midblock crosswalk on a street with both vehicular and pedestrian traffic. The proposed model aims to produce the optimal signal timings at the crosswalk to accommodate both traffic modes and to adjust the offsets of the pedestrian signals for the two stages concurrently to minimize pedestrian delays and relieve congestion at a central refuge island, the safe area for pedestrians to stop. The proposed model and algorithm have three distinguishing features: (a) they explicitly model pedestrian delays at the two-stage controlled crosswalk, including delays at both the curbside and the central refuge island; (b) they model the number of pedestrians waiting on the central refuge island according to the change in signal timing; and (c) they have application in a multiobjective optimization approach to study the effectiveness of mid-block crosswalk control under conditions in which the priorities between vehicular and pedestrian traffic differ. A heuristic based on nondominated sorting genetic algorithm II was designed to solve the model and generate the Pareto solution set for signal timings. The results of the case study showed that the proposed model would help traffic practitioners, researchers, and authorities properly design signal timing plans and central refuge islands for two-stage midblock pedestrian crosswalks.

Use of Genetic Algorithm for Phase Optimization at Intersections with Minimization of Vehicle and Pedestrian Delays

The two objectives of this research were to develop a methodology to optimize signal timing at intersections by minimization of delay for both vehicles and pedestrians and to establish guidance for the selection of the pedestrian crossing phase (two-way or scramble) and the length of the “Walk” phase when the scramble crossing pattern was used. An optimization procedure for signal plans was developed for an isolated intersection. The procedure can provide up to four vehicular phases with either the two-way or scramble pedestrian crossing phase. Genetic algorithms were used to find suitable signal plans because of the existence of a large solution set. Furthermore, the proposed genetic algorithm procedure can generate contour diagrams as selection guides to determine appropriate pedestrian crossing phases at an intersection with different combinations of vehicle volumes and pedestrian volumes. The impacts of relative time values, initial vehicle queues, and geometric designs on the pedestrian phase selection were also determined. According to the contour diagrams, to determine appropriate pedestrian crossing phases, not only do pedestrian volumes and right-turning vehicle volumes need to be taken into account but also through (and left-turning) vehicle volumes should be considered. The scramble crossing reduced delay when the conflicting pedestrian and right-turning vehicle volumes in approaches were high and the through (and left-turning) vehicle volumes in the same approaches were relatively lower. Otherwise, the scramble phase increased delay.

Simulation Study of Access Management at Modern Roundabouts: Treatments of Pedestrian Crosswalks

The widespread emergence of modern roundabouts in North America has kindled a controversy about pedestrian access. Almost uninterrupted traffic streams, ambient noises, and urban settings make it difficult for the visually impaired to perceive safe crossing gaps when only auditory cues are used. In 2005, the U.S. Access Board released a revised draft guideline calling for the provision of a “pedestrian-activated traffic signal … for each segment of the crosswalk” to ensure access for vision-impaired pedestrians. The Access Management Manual prescribes major transportation actions encompassing multimodal streets with sidewalks and adequate pedestrian refuges, but the manual does not address the issue of pedestrian access at roundabouts. In North America few roundabouts have been outfitted with pedestrian signals. Little research has explored signalizing roundabouts for pedestrian access improvements. This simulation study quantitatively assessed the performance of four pedestrian signals placed at roundabouts with a wide spectrum of test scenarios resulting from varied crosswalk layouts, installation schemes, and operational conditions. A two-stage installation scheme was found more operationally efficient than a one-stage scheme; with the two-stage scheme, no significant differences existed between three layouts. When a one-stage scheme operated, a distant layout reduced vehicle delay and queue length because of enlarged storage space. High-intensity activated crosswalk signals induced minimum vehicle delay, and pedestrian user-friendly interface signals minimized pedestrian delay while fully protecting pedestrians. The findings provide an objective basis for identifying crosswalk treatments to improve roundabout accessibility and are informative for transportation policy makers, planners, and practitioners in the access management community who work at enhancing roundabout accessibility for pedestrians.

Towards the pedestrian delay estimation at intersections under vehicular platoon caused conflicts

This paper attempts to develop a pedestrian delay estimation model for intersections considering automobile-pedestrian conflicts induced by driver’s bad behaviour of not giving way to pedestrians. Firstly, level of service (LOS) divisions for signalized and unsignalized intersection crosswalks for pedestrians in China are proposed and 6 levels are ranked using the pedestrians' perceptions of comfort, safety and psychological limitation as well as acceptable delay. Then pedestrian delay is analyzed at non-signalized intersection and signalized intersection, and the latter is divided into two parts: signal delay and interrupted delay based on whether pedestrian signal and vehicle signal are separated thoroughly. For the case of signal control, delay estimation model is constructed with pedestrian gathering and dissipating characteristics. In order to test the effectiveness of this proposed delay estimation model, we use Vissim to simulate the pedestrian delay at signalized and unsignalized intersections. Compared with the simulated delay, the delay values derived from this proposed model has better performance of EI (error indicator) in response to the observed ones, providing useful reference in improving pedestrian crossing environment at intersections. Key words: Pedestrian delay estimation, signalized intersection, level of service, Vissim simulation.

Mixed-Priority Pedestrian Delay Models at Single-Lane Roundabouts

This paper presents an approach for developing mixed-priority pedestrian delay models at single-lane roundabouts using behavioral crossing data. Mixed-priority refers to crosswalk operations where drivers sometimes yield to create crossing opportunities, but where pedestrians sometimes have to rely on their judgment of gaps in traffic to cross the street. The models use probabilistic behavioral parameters measured in controlled pedestrian crossings by blind pedestrians as part of NCHRP project 3-78a. While blind pedestrians clearly represent a special population of pedestrians, the developed delay model is structured to be applicable to any pedestrian population. Delay is predicted as a function of the probability of encountering a crossing opportunity in the form of a yield or crossable gap, and the probability of utilizing that opportunity, which are combined to produce an overall probability of crossing. The paper presents the theoretical approach to estimating the probability parameters and uses a multi-linear log-transformed regression approach to predict the average pedestrian delay. The final delay model explains 64% of the variability in the observed data and therefore represents a reasonable model for predicting pedestrian delay at single-lane roundabouts. The paper concludes with a discussion of how agencies can estimate the underlying probability parameters for existing or proposed roundabouts using empirical and theoretical approaches, and how pedestrian crossing treatments can be used in the context of the model to reduce average pedestrian delay. The research is important in light of the ongoing debate of the accessibility of modern roundabouts to pedestrians who are blind.

Pedestrian Delay at Signalized Intersections with a Two-Stage Crossing Design

An improved pedestrian delay model was developed for signalized intersections with a two-stage crossing design. This model provides a timely enhancement tool for the Highway Capacity Manual for conducting multimodal-oriented level of service assessments at signalized intersections with unconventional pedestrian crossings. The proposed model is presented in a general form that provides estimation of three portions of pedestrian delay involved in a two-stage crossing: the first-stage delay; the second-stage delay for pedestrians who crossed during the Walk phase of the first stage; and the second-stage delay for pedestrians who crossed during the flashing Don't Walk and Stop phases of the first stage. The model was validated through microscopic simulation under a wide range of traffic scenarios. Statistical analysis suggests that the proposed model is able to give satisfying results (R2 = 99.9%, p-value = .000). The model can be applied in various cases knowing some basic input parameters and variables.

Multimodal Accessibility of Modern Roundabouts

Modern roundabouts have become popular in North America during the past decade. This popularity can be attributed to their great success in Europe and Australia. There has been significant debate, however, over their accessibility for pedestrians. With almost uninterrupted traffic flows, roundabouts make it difficult for the visually impaired to determine safe gaps, as they rely on auditory cues alone. Such crossing is particularly complicated by ambient noises and circulating vehicles on busy urban roundabouts. Various pedestrian signals have been installed at roundabouts overseas. The United States Access Board published a draft guideline proposing pedestrian signals at all roundabout crossings to ensure access for the visually impaired. Roundabout operations can be a complex process of transporting multimodal travelers. There is increased interest in harnessing artificial intelligence to address issues to improve transportation systems. This research developed a crosswalk signal and introduced fuzzy logic control (FLC) into the signal timing to accommodate roundabout users. The system was assessed against the Pedestrian User-Friendly Intelligent (PUFFIN) crossings under varied geometries under different traffic conditions. The objective was to identify potential treatments for improving roundabout accessibility, safety, and efficiency. The results reveal that “distant” layout reduces vehicle delays and queue lengths when the FLC signal is applied, especially under saturated traffic conditions. From safety and operational perspectives, the FLC signal outperforms PUFFIN. The FLC signal implements the signal timing effectively, decreases pedestrian delay, and maintains adequate vehicle circulation. Multimodal traveler needs at a modern roundabout are satisfied in manifold ways.

Right Turns on Green and Pedestrian Level of Service: Statistical Assessment

Traditional pedestrian level of service measures at signalized intersections are based on pedestrian space and pedestrian delay. However, these measures may not adequately reflect the negative impact of right-turning traffic on pedestrians. This paper presents a statistical analysis using a binary logit model that provides new insights into the factors that affect the likelihood that a pedestrian is compromised (delayed, altered their travel path, or altered their travel speed) in response to traffic turning right (on green) during concurrent vehicle/pedestrian signal timing. The statistical analysis indicates that a number of factors affect the likelihood of a pedestrian being compromised including pedestrian direction of travel, right-turn traffic volume, number of pedestrians crossing, whether the pedestrian arrived late and began crossing after the end of the walk interval, and the crosswalk characteristics including location (downtown versus suburban) and one-way/two-way streets.

Multi-objective signal control of urban junctions – Framework and a London case study

This paper presents an approach to multi-objective signal control using fuzzy logic. The signal control uses fuzzy logic where the membership functions are optimised according to the Bellman–Zadeh principle of fuzzy decision-making. This approach is both practical for the decision-maker and efficient, as it leads directly to a Pareto-optimal solution. Signal control priorities are ultimately a political decision. Therefore the tool developed in this research allows the traffic engineer to balance the objectives easily by setting acceptability and unacceptability thresholds for each objective. Particular attention is given in the example to pedestrian delays. The membership functions of the fuzzy logic are optimised by a genetic algorithm coupled to the VISSIM microscopic traffic simulator. The concept is illustrated with a case study of the Marylebone Road–Baker Street intersection in London at which pedestrians as well as vehicle flows are high. The results prove the feasibility of the framework and show the vehicle delays for a more pedestrian friendly signal control strategy.

Trade-offs between vehicular and pedestrian traffic using micro-simulation methods

A simple hypothetical network is analysed using the VISSIM micro-simulation model to study the effects of signal cycle timings on delay and travel time costs for both vehicles and pedestrians in various pedestrian phasing scenarios. To examine cost trade-offs between pedestrians and vehicles various multi-attribute weighting criteria are applied to different components of travel delay using relative values of time. Results show that the policy selection when considering pedestrians may differ from that when just considering vehicular traffic, which is currently standard practice. The multi-criteria analysis approach developed here makes it possible to optimise network performance and costs across all modes of travel.

Assessing the Impact of Turning Vehicles on Pedestrian Level of Service at Signalized Intersections

The Highway Capacity Manual provides two methods, based on delay and space, for the assessment of pedestrian level of service (LOS) at signalized intersections. Current procedures for evaluating pedestrian LOS are examined, and results indicate that these procedures do not adequately reflect the negative impact of turning vehicles. Pedestrian LOS measures are proposed to reflect not only pedestrian delay and space but also traffic interruptions, freedom of movement, and comfort. These measures are consistent with LOS measures currently used for freeway segments and ramp merge areas. The percentage of compromised pedestrian crossings is proposed as a means to quantify the negative impact of turning vehicles on pedestrian service and as a LOS measure at signalized intersections. A pedestrian crossing is designated as compromised if a pedestrian is delayed or is forced to change travel path or speed in response to a turning vehicle. The percentage of compromised pedestrian crossings was assessed for 13 crosswalks. Results of the assessments illustrate that as right-turn volumes increase, the percentage of compromised pedestrian crossings increases. The proposed method provides an objective engineering tool for measuring the impact of turning vehicles on pedestrian service. It may be appropriate to use this measure to quantify the need for pedestrian improvements (e.g., if the percentage compromised exceeds 15%, then it may be appropriate to implement a leading pedestrian interval or other enhancement).

Influence of Pedestrians’ Entry Process on Pedestrian Delays at Signal-Controlled Crosswalks

The writers claim that the process of pedestrians' entry to the signal-controlled crosswalk can affect the values of pedestrian delays. The existing models have been based on some typical situations and would not always consider the character of pedestrians' entry process. The use of these models for crosswalks where pedestrians' entry process is not uniform can lead to inaccurate estimation of pedestrian delays. A number of measurements have been carried out, recording the entry process and the delays. The delay values estimated using the existing models have been compared with the values from field measurements. The comparison has proved that there are situations in which the existing models do not provide accurate estimation of delays. Therefore, three new delay estimation models have been proposed. They differ in the degree of accuracy and complexity as well as practical utility. The results obtained using the new models have been compared with the results of field measurements. At the end of the paper the sensitivity of all the models to the selected parameters has been analyzed. Finally, a conclusion and evaluation of the whole research close this paper.

Inefficient emergent oscillations in intersecting driven many-particle flows

Oscillatory flow patterns have been observed in many different driven many-particle systems. It seems reasonable to assume that the emergent oscillations in opposing flows are due to or related to an increased efficiency (throughput). In this contribution, however, we will study intersecting pedestrian and vehicle flows as an example for inefficient emergent oscillations. In the coupled vehicle–pedestrian delay problem, oscillating pedestrian and vehicle flows form when pedestrians cross the street with a small time gap to approaching cars, while both pedestrians and vehicles benefit, when they keep some overcritical time gap. That is, when the safety time gap of pedestrians is increased, the average delay time of pedestrians decreases and the vehicle flow goes up. This may be interpreted as a slower-is-faster effect. The underlying mechanism of this effect is explained.

Walking in Waikiki, Hawaii: Measuring Pedestrian Level of Service in an Urban Resort District

This study examines pedestrian conditions in Waikiki, the most urbanized area in Honolulu, Hawaii. Focusing on one side of approximately a four-block stretch of Kalakaua Avenue, a series of 15-min pedestrian counts was conducted to establish overall sidewalk volumes and flows. Detailed maps were produced to characterize the physical environment and to identify potential factors associated with measurement of the pedestrian environment. Next, the pedestrian level of service (LOS) was estimated. A variety of factors affect the pedestrian environment. In addition to the width of the sidewalk, there are also movable and immovable objects, street furniture, plantings, and other activities that affect access and use of sidewalks. The intent of this study was to understand and measure better the impacts of sidewalk activities on LOS. To test and refine the approach, the impacts of street performers who occupied the sidewalks in the area were analyzed in terms of the effects on pedestrian flow and LOS. Street performers create the following kinds of impacts to the pedestrian environment: (a) increased delay, (b) direction changes and longer travel paths for pedestrians, (c) increased traffic conflicts as pedestrians step into moving motorized traffic to avoid congestion, (d) disruption of pedestrian platoons or preferred side of sidewalk for travel (generally, most pedestrians prefer to walk on the right side of the sidewalk), and (e) increased confusion associated with crowding and forced changes in direction. Policy considerations as well as directions for research are discussed in a concluding section.

Exploratory Analysis of Crossing Difficulties for Blind and Sighted Pedestrians at Channelized Turn Lanes

This paper presents the findings from a paired comparison study of blind and sighted pedestrians judging crossing opportunities in traffic from the roadside at three channelized turn lane (CTL) locations. It is motivated by the belief that the geometric nature of CTL facilities and the lack of signal control at the pedestrian crossing are factors that may negatively affect the delay and safety for blind pedestrians. Pedestrians waiting at the curb must judge the traffic moving in a circular motion, and they must deal with a significant amount of background traffic (i.e., noise) present at the main intersection. The findings show that crossings at all CTL crossing locations are significantly more difficult for blind pedestrians than for sighted pedestrians. Blind pedestrians tend to face a greater risk and a greater amount of delay. Furthermore, the research shows that conflicting traffic flow in the turn lane has a significant effect on crossing performance for both pedestrian groups; however, the effect of noise-generating background traffic on blind pedestrian crossings is not significant. The study also concludes that for this experiment the location of the crosswalk (in the center of the turn lane or at the downstream end) does not have a significant effect on crossing judgment performance.

Walking in Waikiki, Hawaii

This study examines pedestrian conditions in Waikiki, the most urbanized area in Honolulu, Hawaii. Focusing on one side of approximately a four-block stretch of Kalakaua Avenue, a series of 15-min pedestrian counts was conducted to establish overall sidewalk volumes and flows. Detailed maps were produced to characterize the physical environment and to identify potential factors associated with measurement of the pedestrian environment. Next, the pedestrian level of service (LOS) was estimated. A variety of factors affect the pedestrian environment. In addition to the width of the sidewalk, there are also movable and immovable objects, street furniture, plantings, and other activities that affect access and use of sidewalks. The intent of this study was to understand and measure better the impacts of sidewalk activities on LOS. To test and refine the approach, the impacts of street performers who occupied the sidewalks in the area were analyzed in terms of the effects on pedestrian flow and LOS. Street performers create the following kinds of impacts to the pedestrian environment: ( a) increased delay, ( b) direction changes and longer travel paths for pedestrians, ( c) increased traffic conflicts as pedestrians step into moving motorized traffic to avoid congestion, ( d) disruption of pedestrian platoons or preferred side of sidewalk for travel (generally, most pedestrians prefer to walk on the right side of the sidewalk), and ( e) increased confusion associated with crowding and forced changes in direction. Policy considerations as well as directions for research are discussed in a concluding section.

Exploratory Analysis of Crossing Difficulties for Blind and Sighted Pedestrians at Channelized Turn Lanes

This paper presents the findings from a paired comparison study of blind and sighted pedestrians judging crossing opportunities in traffic from the roadside at three channelized turn lane (CTL) locations. It is motivated by the belief that the geometric nature of CTL facilities and the lack of signal control at the pedestrian crossing are factors that may negatively affect the delay and safety for blind pedestrians. Pedestrians waiting at the curb must judge the traffic moving in a circular motion, and they must deal with a significant amount of background traffic (i.e., noise) present at the main intersection. The findings show that crossings at all CTL crossing locations are significantly more difficult for blind pedestrians than for sighted pedestrians. Blind pedestrians tend to face a greater risk and a greater amount of delay. Furthermore, the research shows that conflicting traffic flow in the turn lane has a significant effect on crossing performance for both pedestrian groups; however, the effect of noise-generating background traffic on blind pedestrian crossings is not significant. The study also concludes that for this experiment the location of the crosswalk (in the center of the turn lane or at the downstream end) does not have a significant effect on crossing judgment performance.

Validation of HCM Pedestrian Delay Model for Interrupted Facilities

The Highway Capacity Manual (HCM) 2000 equation for pedestrian delay at signalized intersections assumes that pedestrian arrivals at those intersections are random. However, if a significant percentage of those pedestrians are arriving from an upstream coordinated signal, the arrival rate may not be random and the average delay may be quite different from that which would be predicted. Two studies were conducted to test the HCM model for pedestrian delay at coordinated signalized intersections. Data collected at six intersections in St. Louis indicated that pedestrian arrivals at these locations were significantly affected by upstream signals. A study of delays along an arterial in Columbia, Mo. showed that 24 out of 30 data sets had delays that were significantly different from those expected from the HCM 2000 delay equations. 29 of the 30 data sets had variances of delay significantly lower than expected if arrivals were random. The results from these studies indicate that delay calculations for signalized intersections in coordinated systems should recognize the effect of signal coordination.