A THEORETICAL OVERVIEW OF ROAD HUMP EFFECTS ON TRAFFIC SPEED IN RESIDENTIAL ENVIRONMENTS <s> Public Perception on Effectiveness of Road Hump <s> This study examined the impact of speed humps and speed tables on vehicle speed profiles, mean vehicle speed, 85th percentile vehicle speed, and frequency of speeders on the City of Atlantic, Iowa. Temporary speed humps and speed tables were installed on 2 residential streets and speed data was collected during 4 periods: 1) before the speed hump was in place, 2) while the speed hump was in place, 3) while the speed table was in place, and 4) after devices were removed. Speed data was collected and evaluated upstream of the devices, at the devices, and downstream of the devices. It was concluded that the speed humps and speed tables effectively reduced mean vehicle speed and 85th percentile vehicle speed at and downstream of the devices, but not upstream of the devices. An evaluation of 85th percentile speed indicated that these devices are as effective in small rural cities as they are in more urbanized areas. <s> BIB001 </s> A THEORETICAL OVERVIEW OF ROAD HUMP EFFECTS ON TRAFFIC SPEED IN RESIDENTIAL ENVIRONMENTS <s> Public Perception on Effectiveness of Road Hump <s> PROBLEM ::: The effectiveness of speed humps, 14 ft (4.3 m) wide by 3.5 in (8.9 cm) high, and tables, 22 ft (6.7 m) wide, on 12 streets in Salt Lake City, Utah was investigated. Mean and 85th percentile spot speeds, speed limit compliance, motor-vehicle crashes, and resident opinions were considered. ::: ::: ::: METHOD ::: Spot speeds were collected at 18 "between-hump" locations. Motor-vehicle crash data were obtained for "before" and "after" periods of equal duration. A total of 436 residents were surveyed; 184 responded. ::: ::: ::: RESULTS ::: The mean and 85th percentile speeds decreased at 14 and 15 locations, respectively. The average reduction in the 85th percentile speed (3.4 mph or 5.4 km/h) was significant in flat and rolling terrain, but not on uphill or downhill segments. The number of sites with 50% speed limit compliance increased from 4 to 12. The number of motor-vehicle crashes decreased from 10 to 9; the change was not significant, but injury crashes decreased from five to one. Regarding the residents, 30% were positive, 25% were negative, and 45% offered suggestions, some of which were conflicting. ::: ::: ::: DISCUSSION ::: Further study is needed on speed hump spacing and speed tables in hilly terrain. Example results should be shared with residents to inform their decision-making. ::: ::: ::: SUMMARY ::: At least 78% of the sites experienced a decrease in the mean or 85th percentile speed, or an increase in speed limit compliance. ::: ::: ::: IMPACT ON INDUSTRY ::: These findings should be useful to agencies that are planning or implementing traffic calming projects, and to analysts. <s> BIB002
Based on the available literature, the public perception on road humps have generally been positive in regards to speed reductions. A study by  made use of questionnaires targeting a sample of 150 drivers from commercial, private, company and government sectors. The study focused on the perception regarding road bumps; however it found that speed reductions were deemed to be significantly affected by bump type, height, width and spacing. This is concurrent with the literature discussed above on the effects of hump dimension and spacing. In their study, BIB002 found that a common positive comment given by the respondents was that the humps reduced traffic speed and volume. This concurred with Du et al. (2001) , which studied the perceptions of the residents and travelling public who regularly used the roads and found that both groups agreed on the humps' effectiveness in reducing vehicle speeds. BIB001 also reported that after installing temporary road humps, residents agreed that the humps reduced vehicle speeds up to 50 percent. On the other hand, BIB002 and Du et al. (2001) noted that respondents also complained about drivers speeding aggressively to 'fly' over the humps or driving along the edge of the humps in order to avoid driving over the humps. However this is indicative of variations in driver behavior when navigating over a road hump, and not necessarily an issue regarding the hump design or spacing. Other complaints by the respondents were mostly on the increase in traffic noise levels near the humps (Du et al., 2001; BIB001 BIB002 , due to abrupt changes in vehicle speed due to vehicle decelerations and accelerations. Thus it can be generalized that the road hump is effective in addressing the concerns on increased vehicle speeds in residential areas.