Pedestrian Signal Safety - AAA Foundation for Traffic Safety

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Orange County, California
Figure 13 and Table 21 show the total intersection LOS and ADPV for the Orange County, California
case study intersection under various peak-hour traffic volume and pedestrian walking speed
scenarios. Table H-11 in Appendix H shows the intersection operational and geometric characteristics
for the Orange County case study intersection.
Because volume data were not available from the jurisdiction, existing volumes were estimated
based on the operational and geometric characteristics of the intersection. Total intersection volume
was estimated at 6,500 peak-hour vehicles, with 2,000 vehicles and 1,250 vehicles on the major
and minor street approaches, respectively. This approach produced more of a saturated/lower LOS
condition at a “base” scenario level similar to the base condition LOS at the Montgomery County,
Maryland case study intersection.
Table 21 shows there was a uniform increase in ADPV for the volume scenario that was 5 percent
above existing volumes. Here, there was a greater vehicular delay at pedestrian walking speeds of
4.00 ft./sec., 3.50 ft./sec., and 3.00 ft./sec. (in that order). The ADPV was 72 sec., 68 sec., and 55
sec., respectively. This trend remained the same for volume scenarios to 10 and 15 percent above
existing volumes.
The total intersection LOS decreased from LOS D to LOS F under the 3.00 ft./sec. walking speed
scenario when existing volume conditions were compared to a modeled increase of 10 percent above
existing volume conditions. Concomitantly, there was a corresponding increase in ADPV of 75 sec.
An incremental increase of another 5 percent of peak-hour volume (to 15 percent above existing
volumes) at the 3.00 ft./sec. pedestrian walking speed added 47 sec. to the ADPV. Thus, from existing
volume conditions to a modeled increase of 15 percent over existing volumes, there was a reduction
of two LOS designations (from LOS D to F) and a corresponding increase in 122 sec. for ADPV.
Under the 3.50 ft./sec. pedestrian walking speed scenario, the delay for the 3.50 ft./sec. scenario
increased at a greater rate than the 3.00 ft./sec. scenario until traffic volumes were increased
between 5 and 10 percent. This occurred because the 3.00 ft./sec. scenario provided more green
time for the minor street due to the increase in the PCI for the parallel pedestrian movement. Under
the 3.50 ft./sec. pedestrian walking speed scenario and under a scenario that increased existing
volumes by 15 percent, the total intersection LOS decreased from LOS D to F and there was a
corresponding increase of 108 sec. in ADPV.
At the 4.00 ft./sec. pedestrian walking speed scenario, a large increase in ADPV occurred at the
existing level to 5 percent above existing volume conditions (17 sec.), following smaller increases
exhibited in the modeled 5 to 10 percent above existing conditions volume level (4 sec.) and at
the modeled 10 to 15 percent above existing conditions volume level (6 sec.). The total increase
in average intersection delay per vehicle from the existing volume condition level to the 15 percent
above existing volume condition level was 28 sec. and there was a reduction of one LOS designation
from LOS E to F. Note that the difference in ADPV between the 15 percent above existing volume
condition and the existing volume condition at the 3.00 ft./sec. and 3.50 ft./sec. pedestrian walking
speed scenarios was 94 sec. and 80 sec., respectively.
A discussion of LOS and AVD for the major and minor approaches is included in Appendix H to this
report. Table H-12 and Figures H-3, H-4, and H-5 in Appendix H show intersection delay for major and
minor street approaches at walking speeds of 3.00, 3.50, and 4.00 ft./sec. at the Orange County case
study intersection.