A Look at Traffic

Case studies to allow an analysis of traffic.

Tuesday, April 13, 2010

Pedestrian Behavior at Crosswalks and Pedestrian-Motor Interactions - Written by David Kim

One aspect of traffic that is not usually thought of as part of congestion is pedestrians. Just as vehicles use the roads and the network system to travel, pedestrian are able to do the same sometimes causing more congestion or even accidents. Though, the amount of pedestrian injuries and death have decreased over the years, there is a clear sign that there are still a large number of pedestrian being injured each year (~100,000) and pedestrian deaths each year (~4700) in the United States1. Pedestrian deaths alone make up of about 11 percent of all motor vehicle deaths2.

While these accidents are undoubtedly uncommon, t
hese statistics alone make it important to evaluate the factors which play into these injuries and deaths. One of the goals of transportation planning and engineering is to ensure safety to all those who use the system.
There are many factors which play a role in pedestrian/motor accidents. Such factors would include age of the pedestrians, pedestrian walking speeds, vehicle speeds, road width, and etc.
- Through different studies and observations, it is noted that the elderly and children are more prone to these accidents which involve pedestrian/motor incidents.
Pedestrian Speed
- The Federal Highway Administration (FHWA) suggests pedestrian walking speed of 4 ft/sec be used in traffic signal timing3. At the same time it was noted by FHWA that a little less than one-third of pedestrians walk at or below 4 ft/sec4. However, this noted pedestrian walking speed would obviously depend on many factors such as age and location and so forth.

Case Study –
Irvine, CA
Data was collected at Bridge Ave and Campus Dr. to evaluate the average speed of pedestrians, and also determine whether this 4 ft/sec standard for traffic signal timing was adequate for safe passage for pedestrians. Pedestrians were timed from the moment they stepped off the curb to the moment that step onto the curb of the opposite side of the roadway. The actual walking speed was calculated by using Google Earth and measuring the distance for each crosswalk, and using that distance to divide the time spent crossing the street. A total of 78 pedestrian were timed at the intersection from 12:45pm to 1:45pm. The signal timing was also accounted for at this intersection, and as a result it was noted that this particular intersection followed the suggested standard of 4 ft/sec.
(All Sample Data)
All Pedestrians
Single walking Pedestrians
Pedestrian in pairs
# in sample
MeanWalking Speed
Table 1 – Data Collected from Bridge Ave. and Campus Dr. intersection
Once the data was collected a hypothesis test was performed on all 5 categories listed in table 1.
Figure 1 – Histogram of pedestrian speeds


One factor that is looked into further was the possibility that males jaywalk more often than females would, and thereby assuming that there is a correlation between jaywalking and an increase in deaths. The method of determining if there is a correlation was to first take a survey on males and female preferences of jaywalking. The goal was to obtain at least 30 male responses and female responses. A simple survey containing 3 questions was distributed in to obtain data. The 3 questions included determining their sex, their rating on the danger of jaywalking (a rating from 1=safe to 10=dangerous), and how often they jaywalk per month. The survey was then distributed to a large group of friends. Most were college age students, but some adults. A total of 74 responses was collected that which included 39 responses from males and 35 from females.
Figures 2 & 3 – Histogram of Perceived Jaywalking Danger. Males on the left and females on the right
Figures 4 & 5 – Histograms of Jaywalking Frequency. Females on the left and Males on the right.
In conclusion from the data and results of the hypothesis testing it was shown that there is an obvious difference between males and females in terms of their perceived danger of jaywalking as well as the frequency as to which they jaywalk. Nevertheless, note must be taken to the fact that the sampling frame for the population which is desired is not to accurate, as the sampling frame consisted mainly of young adults of a particular group. Therefore, it is able to provide a grounded assumption in stating that males then do jaywalk more often than females, and males view jaywalking less dangerous than females do thereby possibly correlating with why 70% of pedestrian deaths are males.

Pedestrian Accident Prevention

In the end, the purpose of evaluating different pedestrian characteristics or behaviors is to be able to implement solutions pedestrian accidents. There are various methods being implemented to reduce the amount of accidents occurring with pedestrian/motor incidents. However, according to the National Highway Safety Traffic Administration (NHSTA), from the year 1998 to 2008 there has only been a 16% decrease in pedestrian deaths5, while there being no defined factor as to whether this decrease is due to prevention methods or not.

Figure 6 - Pedestrian Deaths from 1997 to 2008

First, it is necessary to identify different types of measures being taken. These methods can be separated into 4 sections: managing vehicle speeds, separating vehicles and pedestrians in time, separating vehicles and pedestrians in space, and increasing visibility and awareness for motorists6. Four methods from these groups will be looked upon in this paper and they include marked vs. unmarked crosswalks, and signs, advanced stop signs, and flashing amber lights.

· Signs, Advanced Stop Lines, and Flashing Amber LightsThis creates a greater awareness for motorist as they approach areas where pedestrians may be crossing. Studies have shown that signs, advanced stop lines, and flashing amber lights revealed that addition of signs and advanced stop lines increased motorist awareness which led to a lower amount of vehicular/pedestrian conflicts at the crosswalks7. The flashing amber lights did not significantly improve any pedestrian safety.
Marked V.s. Unmarked Crosswalks - One method that has been used worldwide as a measure to “increase” safety in pedestrians is the use of marked crosswalks. The reason marked crosswalks have been used in the first place it to further provide safety in ensuring the pedestrian safe passage as they cross a street. Marked crosswalks have usually been placed in uncontrolled locations and midblock locations. One of the reasons why is to increase visibility and awareness of the motorist as they approach crosswalks, thereby prompting earlier slowing down of cars and so forth. However according to many papers and studies there has been an assumption made that marked crosswalks possibly give a false sense of security.

Pedestrian deaths and injuries due to vehicular/pedestrian collisions continue to occur even while measures are being taken. In reality, pedestrian deaths per year in the US have not declined much over the past 10 or more years. Factors and characteristics need to be analyzed continuously in order to fully determine what measures would be effective in being a solution to this problem at hand. From this study it has been noted that jaywalking may be a concern for males as males make up of 70% pedestrian deaths each year, and through a series of data collection, surveying, and analysis, it has been shown that males tend to view jaywalking less dangerous and jaywalk more than their opposing gender. Furthermore, an evaluation of the FHWA suggested speed of 4 ft/sec for traffic signal timing was performed. Results showed that this speed holds and accommodates most pedestrians. However, for both of these tests, proportional sampling was not exercised as the primary group found in both sampling frames consisted of college age students and young adults. Therefore, age groups such as the elderly and young children were underrepresented or not even represented at all. However, the tests performed and the data collected provides starting assumption/foundations for such analysis.
However, one of the largest problems encountered with the analysis of pedestrian accident prevention is the fact that it is a rare occurring event. Though data may be found on the subject in databases stored by NHTSA, the amount of accidents is so low and so disperse that it makes it difficult for the evaluation of different factors that may correlate with the occurrence of these accidents as well as the effectiveness of implemented methods. As a result only through further testing and studies, can this problem be minimized.


1 Retting, Richard A. “A Review of Evidence-Based Traffic Engineering Measures Designed to Reduce Pedestrian-Motor Vehicle Crashes” American Journal of Public Health.Vol. 93, No. 9. 2003

2 Retting, Richard A. “A Review of Evidence-Based Traffic Engineering Measures Designed to Reduce Pedestrian-Motor Vehicle Crashes” American Journal of Public Health.Vol. 93, No. 9. 2003

3 Tarawneh, Mohammed S. “Evaluation of Pedestrian Speed in Jordan with Investigation of Some Contributing Factors”. Journal of Safety Research. Vol. 32. 2001, 229-236.

4 Tarawneh, Mohammed S. “Evaluation of Pedestrian Speed in Jordan with Investigation of Some Contributing Factors”. Journal of Safety Research. Vol. 32. 2001, 229-236.

5 NHTSA’s National Center for Statistics and Analysis. Traffic Safety Facts - 2008 Data – Pedestrians. www.nhtsa.gov

6 Retting, Richard A. “A Review of Evidence-Based Traffic Engineering Measures Designed to Reduce Pedestrian-Motor Vehicle Crashes” American Journal of Public Health.Vol. 93, No. 9. 2003

7 Houten, Ron Van. “The Influence of Signs Prompting Motorists to Yield Before Marked Crosswalks on Motor Vehicle-Pedestrian Conlficts at Crosswalks with Flashing Amber”. Accident Analysis and Prevention. Vol. 23, No. 3. 1992, 217-225.


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