Shawn Turner

Another Look at Pedestrian Walking Speed

Pedestrians have a wide range of needs and abilities. FHWAs Manual on Uniform Traffic Control Devices for Streets and Highways includes a walking speed of 4.0 ft/s (1.2 m/s) for calculating pedestrian clearance intervals for traffic signals. It also includes a comment that where pedestrians who walk slower than normal, or pedestrians who use wheelchairs, routinely use the crosswalk, a walking speed of less than 4.0 ft/s should be considered in determining the pedestrian clearance times. A 2005 TCRP-NCHRP study found a 15th percentile walking speed for young pedestrians of 3.77 ft/s (1.15 m/s) and a 15th percentile walking speed for older pedestrians of 3.03 ft/s (0.92 m/s). The study also determined that there is a statistical difference in walking speeds between older (older than 60 years) and younger (60 years and younger) pedestrians. Using population projections and the 15th percentile walking speeds for each population group more than 15 years old, the proportionally weighted 15th percentile walking...

Motorist Yielding to Pedestrians at Unsignalized Intersections: Findings from a National Study on Improving Pedestrian Safety

This paper evaluates engineering treatments that can be used to improve the safety of pedestrians crossing in marked crosswalks on busy arterial streets. The research team collected extensive data at 42 study sites in different regions of the country to gauge the effectiveness (as measured by motorist yielding or stopping) of various engineering treatments. Motorist yielding data were collected for crossing pedestrians from the general population as well as for crossings staged by the research team. In preliminary analyses, the treatments were grouped into three categories based on function and design: (a) red signal or beacon devices, (b) active when present devices, and (c) enhanced and high-visibility treatments. The authors found the red signal or beacon devices to be the most effective, with yielding rates exceeding 94% for all study sites. Other treatments had various rates of motorist yielding, and several variables (number of lanes and speed limit in particular) were statistically significant in...

MEASURING AND ESTIMATING CONGESTION USING TRAVEL TIME-BASED PROCEDURES

Procedures are presented for measuring and estimating roadway congestion levels. An assessment of users, uses, and audiences indicates a need for congestion measures that are understood by nontechnical audiences, yet are rigorous enough for technical analyses. Travel time-based measurements are deemed most useful for this wide range of needs. Data collected for an NCHRP project were used to identify the number of travel time observations and roadway segments required for reliable estimates of congestion through direct data collection. The data and previous congestion studies were used to develop surrogate procedures that can estimate congestion statistics with readily available traffic count and roadway inventory data. The surrogate estimation procedures were developed to assist agencies when direct data collection is not practical or feasible. Both of these processes—direct measurement and estimation of travel time-related quantities—are important for quantifying congestion.

Analysis of Effects of LED Rectangular Rapid-Flash Beacons on Yielding to Pedestrians in Multilane Crosswalks

This study examined the effects of LED rectangular rapid-flash yellow beacons (RRFBs) in uncontrolled marked crosswalks in three experiments. In Experiment 1, the RRFB system was evaluated with a two- and a four-beacon system at four multilane crossings. Results showed a marked increase in motorist yielding behavior over the baseline for the two-beacon system and a small but statistically significant further increase with the four-beacon system. The second experiment compared a traditional pedestrian overhead yellow flashing beacon and a traditional side-mounted yellow flashing beacon with the RRFB system. The results showed that the traditional overhead and side-mounted yellow flashing beacons produced a minimal increase in yielding, whereas the RRFB system produced a marked increase in yielding behavior. A third experiment examined the effectiveness of the RRFB system at 19 sites in St. Petersburg, Florida, as well as three additional sites, two in the suburbs of Chicago, Illinois, and one in the Washington, D.C., area. Results indicated that baseline daytime yielding behavior increased from an average of 2% to 86% at the 19 St. Petersburg sites and was 85% at the 2-year follow-up. A time-series intervention regression modeling was employed that estimated the parameters of the model based on a double bootstrap methodology. The results of this analysis confirmed a highly significant level change following the introduction of the RRFB that showed no sign of decay over time. Similar results were obtained at the District of Columbia and Chicago suburb sites. Probe data collected after dark revealed an even larger effect with yielding levels at the middle to high 90% level.