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37 CHAPTER 3 Findings and Applications The goals of this research effort are to develop design guide- accommodate utilities in state transportation facility rights- lines for safe and aesthetic urban roadside treatments and of-way. FDOT included a concept in this document called ultimately to develop a toolbox of effective treatments that "Control Zones" for consideration at facilities with limited balance the needs of all roadway users while accommodating or no access control. Although the emphasis of FDOT's doc- community values. Of particular interest is the design of ument was utility pole placement, the concept of control urban roadways that carry substantial volumes of traffic and zones can be expanded and is a promising approach for are designed for higher operating speeds, thus often raising evaluating an urban roadside environment in its entirety. additional roadside safety concerns. FDOT's Utility Accommodation Manual defines control zones To accomplish these goals, the research team performed as the following: two specific tasks. These two research tasks were as follows: Areas in which it can be statistically shown that accidents are Developing a systematic analysis approach (referred to as more likely to involve departure from the roadway with greater frequency of contact with above ground fixed objects. (117) an Urban Control Zone Assessment) to enable jurisdictions to better target hazardous urban roadside locations and Example control zones include those that contain objects Developing before-after case studies for a variety of urban hit more than two times within three consecutive years, roadside treatments. objects located within the return radii and object horizontal offset distance at an intersecting street, objects located within These two tasks are described in detail in the sections that 1 m (3 ft) of a driveway flare, and objects located along the follow, with specific case information included in Appen- outside edge of a horizontal curve for roads with operating dixes A and B, available online at http://trb.org/news/blurb_ speeds greater than 56 km/h (35 mph). detail.asp?id=9456. Appendix C (included herein) includes a The research team performed a systematic evaluation of toolbox that generally summarizes the safe application of crash data to define common control zones for urban road- roadside elements in an urban environment. A supplemental side environments. To accomplish this task, the research team product of this research effort is draft language for possible in- evaluated urban crash data for four different locations. Study clusion in the urban roadside chapter of the AASHTO Road- areas included urban corridors located in Atlanta, Georgia; side Design Guide. This document is included in Appendix C. Orange County and San Diego County, California; Chicago, Illinois; and Portland, Oregon. Although not all sites were Urban Control Zone Assessment within the same city limits for a regional study, they were all characterized by urban corridors where fixed-object crashes Experimental Design occurred along the corridor (often in cluster configurations). Many urban roadside environments are crowded with The sources of the crash data varied. The Georgia Department potential hazards. The task of identifying which objects pose of Transportation (GDOT) provided Atlanta crash data the greatest risk to users of the road can be daunting for a and road characteristic information. The Oregon Depart- jurisdiction with limited resources. In 1999, the Florida De- ment of Transportation (ODOT) provided Portland crash partment of Transportation (FDOT) developed a document data and road information. For corridors located in Illinois called the Utility Accommodation Manual (117). This docu- and California, the research team used data from the High- ment's purpose was to provide direction for ways to reasonably way Safety Information System (HSIS) database maintained

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38 by FHWA. The research team specifically targeted higher are further identified in Table 14. As members of the research speed urban roads in each of the regions, although some of team evaluated fixed-object crashes at each site, recurring the corridors included transitions to lower speeds. road features emerged at fixed crash locations. Many of these Comprehensive crash data can be informative, but the re- are locations where roadside crashes can be anticipated; search team supplemented this information by collecting cor- however, the information included in Table 14 helps demon- ridor video data for both directions of travel. The team then strate the frequency of these road conditions at the study used this video data to determine the type and placement of locations. roadside objects, adjacent land use, access density, and so The 6-year crash summaries included in Appendix A pres- forth. Table 13 shows the actual corridors evaluated for this ent total crash type information for each study corridor. As is task. The initial goal developed by the research team was a often the case along an urban corridor, a large number of sample of 16 to 32 km (10 to 20 mi) of urban arterial per city; crashes occurred at intersections and driveways. Crashes at however, due to select long corridors with frequent fixed these locations are generally angle, head-on, rear-end, and, in crashes, the California and Illinois data collection consider- some instances, sideswipe crashes. In addition, intersection- ably exceeded this initial data goal. As a result, 244.9 km related crashes often involve more than one vehicle. As a result, (152.3 mi) of urban arterial from a total of four states are crash severity at each study corridor location is further pre- included in this analysis. sented in Table 15, in which crash severity percentages for The goal of this task was to identify urban control zones all crashes are contrasted with crash severity of fixed-object that can be then applied to other regional analyses for project crashes only. The average per state for the study corridors priority and evaluation. These zones are summarized in the representing the percent injured varied from 22.5 percent to sections that follow. 46.1 percent for all crashes (with an overall average of 34.6 per- cent), while fixed-object injury crashes ranged from 22.2 per- cent to 38.3 percent (with an overall average of 29.2 percent). Findings and Recommendations By contrast, fixed-object crash fatalities at all locations were a The various corridors the research team evaluated for larger percentage than for all crashes with a total average of identification of potential urban control zones included a 1.1-percent fatal crashes for all reported fixed-object crashes wide variety of speed limits, physical features, and types of compared with only 0.3-percent fatal crashes for all crash types crashes. In Appendix A, each site is described in detail in- (the "all crashes" statistic includes the fixed-object crashes). cluding observed roadway conditions as well as crash type Table 16 further depicts the total percentage of fixed-object and crash severity information. In addition, the research crashes and pedestrian crashes for the study corridors. The team performed a cluster crash analysis to identify loca- urban fixed-object crashes were approximately 6.7 percent of tions with an overrepresentation of fixed-object crashes. all crashes observed for the four state study corridors. A spot map for each site is also included in the Appendix A The nature of the roadside crashes at these corridor locations summary. Common fixed-object crash features for each site pointed to a common set of frequently hit objects resulting Table 13. Urban control zone sites evaluated in this study. California Sites Georgia Sites Study Corridor Name Length km (mi) Study Corridor Name Length km (mi) S. H. Route 1 11.3 (7.0) Alpharetta Highway 3.5 (2.2) S. H. Route 39 29.3 (18.2) Briarcliff Road 4.2 (2.6) S. H. Route 74 3.2 (2.0) Candler Road 5.6 (3.5) S. H. Route 75 5.3 (3.3) 14th St / Peachtree St 4.8 (3.0) S. H. Route 76 11.3 (7.0) Franklin Road 3.7 (2.3) S. H. Route 78 6.4 (4.0) Moreland Avenue 6.4 (4.0) S. H. Route 90 8.0 (5.0) Roswell Road 1 (Cobb) 3.2 (2.0) Subtotal: 74.8 (46.5) Roswell Road 2 (Cobb) 3.2 (2.0) Roswell Road (Fulton) 3.5 (2.2) Subtotal: 38.1 (23.8) Illinois Sites Oregon Sites Study Corridor Name Length km (mi) Study Corridor Name Length km (mi) Route 6 11.9 (7.4) Beavercreek Rd 3.2 (2.0) Route 14 16.6 (10.3) Brookwood Ave 5.5 (3.4) Route 19(Cook) 9.2 (5.7) Cascade Hwy 1.6 (1.0) Route 19(Dupage) 12.1 (7.5) Evergreen Pkwy 4.3 (2.7) Route 25 13.7 (8.5) Farmington Rd 2.7 (1.7) Route 31 14.0 (8.7) Foster Rd 9.3 (5.8) Route 41 16.6 (10.3) McLoughlin Blvd 2.4(1.5) Subtotal: 94.1 (58.4) 185th Ave 8.9 (5.5) Subtotal: 37.9 (23.6)

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39 Table 14. Urban control zone corridor overview. Lane merge with object offsets Lane merge with object offsets Longitudinal barrier/guardrail maintained at right-turn lanes Numerous roadside obstacles Scenic / tourist location with Roadside at horizontal curve Driveway / intersection with obstacles located on far side with obstacle offsets 46 ft Median at horizontal curve Channelization island very Guardrail wrapped around within 12 ft (on tangent) Roadside ditch with non- obstacles (offset varies) Corridor clear zone not Uneven roadside with traversable headwalls with obstacles 46 ft small with poles close obstacles offset 26 ft curb return 26 ft > 6 ft Case No. Corridor Description UCZ-CA-1 SH 1, Orange County, CA x x x x UCZ-CA-2 SH 39, Orange County, CA x x UCZ-CA-3 SH 74, Orange County, CA x x UCZ-CA-4 SH 75, San Diego County, CA x x x x UCZ-CA-5 SH 76, San Diego County, CA x x UCZ-CA-6 SH 78, San Diego County, CA x x x UCZ-CA-7 SH 90, Orange County, CA x x x UCZ-GA-1 Alpharetta Highway, Fulton x County, GA UCZ-GA-2 Briarcliff Rd., DeKalb County, x x x x GA UCZ-GA-3 Candler Rd., DeKalb County, x x x GA UCZ-GA-4 14th St./Peachtree St., Fulton x x County, GA UCZ-GA-5 Franklin Rd., Cobb County, GA x x UCZ-GA-6 Moreland Dr., DeKalb County, x x x GA UCZ-GA-7 Roswell Rd. (1), Cobb County, x x GA UCZ-GA-8 Roswell Rd. (2), Cobb County, x GA UCZ-GA-9 Roswell Rd., Fulton County, GA x x x UCZ-IL-1 Route 6, Will County, IL x x UCZ-IL-2 Route 14, Cook County, IL x x UCZ-IL-3 Route 19, Cook County, IL x x x UCZ-IL-4 Route 19, DuPage County, IL x x UCZ-IL-5 Route 25, Kane County, IL x x x x UCZ-IL-6 Route 31, Kane County, IL x x x x UCZ-IL-7 Route 41, Cook County, IL x x x x x x x UCZ-OR-1 Beavercreek Rd., Clackamas x x County, OR UCZ-OR-2 Brookwood Pkwy., Washington x x x x County, OR UCZ-OR-3 Cascade Hwy., Clackamas x x x x County, OR UCZ-OR-4 Evergreen Pkwy, Washington x x County, OR UCZ-OR-5 Farmington Rd., Washington x x x County, OR UCZ-OR-6 Foster Rd., Multnomah County, x x x x OR UCZ-OR-7 McLoughlin Blvd., Clackamas x x x County, OR UCZ-OR-8 185th Ave., Washington x County, OR from these crashes, with varying severity levels. Commonly Barrier or guardrail, and hit fixed objects included the following: Embankment. Poles and posts, In addition, roadside furniture may have been impacted, Light standards, but the crash databases classified this type of roadside object Traffic signals, as "other unidentified object." Trees and landscaping, As shown in Table 14, the primary locations for fixed-object Mailboxes, crashes were characterized by several common road and road- Walls and fences, side configurations. Often, locations with these configurations

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40 Table 15. Summary of crash severity distributions for study corridors. All Crashes Fixed-Object Crashes Percent Percent Case No. No Injury Percent Percent No Injury Percent Percent or Injured Fatal or Injured Fatal Unknown Unknown UCZ-CA-1 57.27 42.48 0.26 77.66 21.32 1.02 UCZ-CA-2 55.28 44.13 0.59 74.66 24.80 0.54 UCZ-CA-3 70.30 29.70 0.00 64.29 35.71 0.00 UCZ-CA-4 66.39 33.33 0.28 62.30 37.70 0.00 UCZ-CA-5 29.79 69.09 1.12 56.52 39.13 4.35 UCZ-CA-6 31.72 66.42 1.87 56.41 41.03 2.56 UCZ-CA-7 62.64 37.21 0.14 76.62 23.38 0.00 Average (CA) 53.34 46.05 0.61 66.92 31.87 1.21 UCZ-GA-1 79.48 20.47 0.05 75.00 23.61 1.39 UCZ-GA-2 81.46 18.48 0.06 73.86 26.14 0.00 UCZ-GA-3 75.63 24.25 0.12 74.63 24.63 0.75 UCZ-GA-4 80.23 19.72 0.05 64.02 35.37 0.61 UCZ-GA-5 72.76 27.16 0.08 76.79 23.21 0.00 UCZ-GA-6 75.46 24.43 0.11 71.69 28.31 0.00 UCZ-GA-7 78.33 21.52 0.15 86.49 13.51 0.00 UCZ-GA-8 73.11 26.78 0.11 84.21 15.79 0.00 UCZ-GA-9 80.56 19.31 0.13 72.09 27.91 0.00 Average (GA) 77.45 22.46 0.10 75.42 24.28 0.31 UCZ-IL-1 72.75 26.95 0.30 79.07 18.60 2.33 UCZ-IL-2 79.09 20.64 0.27 78.57 19.05 2.38 UCZ-IL-3 71.63 28.12 0.25 75.68 22.52 1.80 UCZ-IL-4 74.37 25.51 0.12 75.81 24.19 0.00 UCZ-IL-5 68.69 30.78 0.54 72.09 25.58 2.33 UCZ-IL-6 74.35 25.51 0.14 84.00 15.00 1.00 UCZ-IL-7 73.20 26.32 0.49 67.28 30.51 2.21 Average (IL) 73.44 26.26 0.30 76.07 22.21 1.72 UCZ-OR-1 55.91 44.09 0.00 60.00 40.00 0.00 UCZ-OR-2 55.26 44.74 0.00 70.59 29.41 0.00 UCZ-OR-3 46.20 53.80 0.00 50.00 50.00 0.00 UCZ-OR-4 53.90 45.35 0.74 50.00 44.44 5.56 UCZ-OR-5 61.49 38.30 0.21 69.23 30.77 0.00 UCZ-OR-6 58.40 41.13 0.47 44.44 51.85 3.70 UCZ-OR-7 56.79 43.21 0.00 73.33 26.67 0.00 UCZ-OR-8 61.82 38.03 0.15 66.67 33.33 0.00 Average (OR) 56.22 43.58 0.2 60.53 38.31 1.16 Average (4 States) 65.11 34.59 0.30 69.74 29.17 1.10 experienced clustered crashes while much of the roadside along Each of these potential Urban Control Zones is discussed the corridor remained free of crashes. The road and roadside in the sections that follow. configurations that are often involved in fixed-object crashes can be generally grouped into the following: Obstacles in Close Lateral Proximity to the Curb Face or Lane Edge Obstacles in close lateral proximity to the curb face or lane edge; Historically, a lateral offset (referred to as an operational Roadside objects placed near lane merge points; offset) of 0.5 m (1.5 ft) has been considered the absolute Lateral offsets not appropriately adjusted for auxiliary lane minimum lateral (or perpendicular) distance between the treatments; edge of an object and the curb face. As previously indicated, Objects placed inappropriately in sidewalk buffer this offset value enabled vehicle access, that is, a person treatments; could open a car door if the vehicle were stopped adjacent Driveways that interrupt positive guidance and have objects to the curb. This operational offset was never intended to placed near them; represent an acceptable safety design standard, although Three kinds of fixed-object placement at intersections; it was sometimes misinterpreted as being one. The urban Unique roadside configurations associated with high crash environment limits lateral offset distances simply because occurrence; and of the restricted right-of-way widths common to an urban Roadside configurations commonly known to be hazardous. setting.

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41 Table 16. Summary of crash type distributions. Percent Fixed-Object Percent Pedestrian Case No. Percent Others Crashes Crashes UCZ-CA-1 10.1 1.1 88.8 UCZ-CA-2 5.4 2.6 92.0 UCZ-CA-3 8.5 1.2 90.3 UCZ-CA-4 17.1 0.8 82.1 UCZ-CA-5 6.4 0.7 92.9 UCZ-CA-6 14.6 3.0 82.4 UCZ-CA-7 5.5 0.9 93.6 Average (CA) 9.7 1.5 88.9 UCZ-GA-1 1.9 0.5 97.6 UCZ-GA-2 2.6 0.4 97.0 UCZ-GA-3 3.9 1.5 94.6 UCZ-GA-4 2.8 1.0 96.2 UCZ-GA-5 4.7 1.3 94.0 UCZ-GA-6 5.9 1.6 92.5 UCZ-GA-7 5.6 0.8 93.6 UCZ-GA-8 10.7 0.0 89.3 UCZ-GA-9 2.9 1.6 95.5 Average (GA) 4.6 1.0 94.5 UCZ-IL-1 6.4 1.6 92.0 UCZ-IL-2 3.8 1.3 94.9 UCZ-IL-3 4.7 0.8 94.5 UCZ-IL-4 3.6 0.5 95.9 UCZ-IL-5 6.6 2.1 91.3 UCZ-IL-6 4.8 0.4 94.8 UCZ-IL-7 14.8 1.8 83.4 Average (IL) 6.4 1.2 92.4 UCZ-OR-1 2.7 0.0 97.3 UCZ-OR-2 14.9 0.0 85.1 UCZ-OR-3 7.6 0.0 92.4 UCZ-OR-4 6.7 1.1 92.2 UCZ-OR-5 2.8 1.3 95.9 UCZ-OR-6 3.2 1.6 95.2 UCZ-OR-7 9.3 0.0 90.7 UCZ-OR-8 1.8 1.4 96.8 Average (OR) 6.1 0.7 93.2 Average (4 States) 6.7 1.1 92.3 The research team for this project observed several objects frequency. Posts (which could, in some instances, be classified located within inches of the edge of the road for the selected as breakaway) were included in this assessment because these study corridors. In general, these items were utility poles, items are often coded as "poles or posts," so posts could not light standards, street signposts, and trees. Evaluation of the always be evaluated separately in the analysis. role of trees in crashes was difficult because the types of To evaluate fixed-object crashes associated with poles, trees in the selected study corridors varied dramatically and posts, and light standards, the research team viewed the cor- included mature rigid trees as well as small-caliper orna- ridor videos (for both travel directions) and for each location mental trees. Due to the varying nature of the tree placement recorded data for the characteristics listed in Table 17. along the corridors (and the wide range of their frangible For the study corridors extending over the 6-year period, tendencies), the research team often could not identify a a total of 503 crashes into poles, posts, or light standards specific tree involved in the crashes recorded in the crash occurred. Of these, 389 occurred during dry weather, 78 dur- database. Actual crash reports were not available for most of ing wet weather, 4 during ice, 4 during fog, 19 during snow, the locations, so unless a tree exhibited scars, it was not feasi- and 9 during unknown weather conditions. Table 18 depicts ble to determine actual tree types involved in crashes. the distribution of these weather-related crashes on the basis Poles, posts, and light standards, however, were easier to of corridor speed limit. Most crashes occurred during dry and evaluate. The lateral placement of these items was generally wet conditions on roads with posted speed limits of 48 to consistent along short corridor segments. The research team, 72 km/h (30 to 45 mph). therefore, further evaluated crash locations on the basis To evaluate lateral offset to the objects that were hit, Table 19 of crash records for crashes involving poles, posts, and light further shows these crashes aggregated by the posted speed standards to determine common lateral offsets and crash limit and lateral distance category. (The lateral offset was the

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42 Table 17. Pole/post/light-standard variables. Description Available Options Curb: Yes or No Continuous Edge line Present: Yes or No Bike Lane Present: Yes or No Driveway Immediately Upstream of Object Hit: Yes or No Night Hours (10 p.m. to 6 a.m.): Yes or No Weather at Time of Crash: Dry Wet Ice Fog Snow Other or Not Stated Lateral Distance from Curb Face (when present) or Less than 1' Lane Edge (when no curb): 1' 2' 2' 4' 4' 6' 6' 8' 8' 10' 10' 15' 15' 20' Greater than 20' distance from the curb face or lane edge [at locations without Roadside Objects Placed Near Lane Merge Points curb].) Only a small subset of these urban crashes occurred at The placement of roadside objects in the vicinity of lane locations where curb was not present. As a result, Table 20 de- picts the 456 sites where curb was present at the pole, post, or merge points increases the likelihood of vehicle impact light-standard crash location. The cumulative percentage with these objects. The research team identified several demonstrates that, for curb locations, 93.4 percent of all cluster crashes at these lane merge locations: lane drop lo- fixed-object pole/post/light standard crashes occurred within cations, acceleration taper ends, and bus bay exit transi- 1.8 m (6 ft) of the curb face while 82.5 percent of these oc- tions. As shown in Table 14, six sites included cluster curred within 1.2 m (4 ft) of the curb. crashes at taper point locations where fixed objects were This observation, combined with a tendency for clustered laterally located less than 1.8 m (6 ft) from the curb face or crashes (for poles, these occurred along short road segments lane edge (for locations where curb was not present). Clus- with objects laterally positioned close to the road), suggests ter crashes occurred at two additional sites where these that in an urban environment the placement of rigid objects objects were located more than 1.8 m (6 ft) laterally. Lon- should ideally be more than 1.8 m (6 ft) from the curb face and gitudinal placement of objects within approximately 6.1 m no closer than 1.2 m (4 ft) wherever possible. (20 ft) of the taper point increased the frequency of these In addition, the frequency of object impact was greater at crashes. Figure 18 shows two example crash locations with locations where objects were in close proximity to the road and a pole located at lane merge tapers. This increased likeli- located on the outside of a horizontal curve. These crashes oc- hood of fixed-object crashes at lane merge tapers suggests curred at locations where objects were placed on the right edge that an object-free buffer zone at taper points on urban of the road and at locations where objects were placed on me- roadways would eliminate or reduce roadside crashes at dians. This suggests that the lateral offset placement of objects these locations and allow drivers to focus solely on merging at horizontal curves should be increased wherever possible. into the traffic stream. Table 18. Poles/post/light-standard crashes for speed limit thresholds. Speed Limit km/h (mph) 40 48 56 64 72 80 89 Weather (25) (30) (35) (40) (45) (50) (55) Total Dry 0 72 152 29 104 19 13 389 Wet 1 18 26 7 22 2 2 78 Ice 0 0 3 0 1 0 0 4 Fog 0 2 0 0 2 0 0 4 Snow 1 2 1 0 4 1 0 9 Other or Not Stated 1 8 6 2 2 0 0 19 Total: 3 102 188 38 135 22 15 503

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43 Table 19. Lateral distance to objects that were hit for all corridors. Lateral Speed Limit km/h (mph) Distance 40 48 56 64 72 80 89 Cumulative m (ft) (25) (30) (35) (40) (45) (50) (55) Total Percent Percent 03 0 35 71 2 19 1 1 129 25.6 25.6 (01) 37 2 29 44 16 50 13 3 157 31.2 56.8 (12) 713 0 26 32 2 32 2 3 97 19.3 76.1 (24) 1320 1 6 23 8 18 1 0 57 11.3 87.4 (46) 2026 0 3 11 1 11 0 0 26 5.2 92.6 (68) 2633 0 3 4 3 2 4 2 18 3.6 96.2 (810) 3349 0 0 0 3 2 0 6 11 2.2 98.4 (1015) 4966 0 0 3 3 1 1 0 8 1.6 100 (1520) Total: 3 102 188 38 135 22 15 503 100 Lateral Offsets Not Appropriately Adjusted be consistently maintained at extended-length, left-turn lane for Auxiliary Lane Treatments locations. When a lane is added that functions as a higher speed turn lane or a through lane, the roadside objects should At many of the study corridors, roadside objects, such as be shifted laterally as well. utility poles, were placed a considerable distance from the ac- Other auxiliary lane locations can include bike lanes. At these tive travel lane. Often lateral offsets of 3.7 to 4.3 m (12 to 14 ft) locations, the higher speed motor vehicles are further separated existed at mid-block locations; however, at locations with aux- from the roadside environment, so the width of the clear zone iliary lanes, such as extended-length, right-turn lanes devel- should include the bike lane. This does not, however, modify the oped for driveway or intersection turning movements, the recommended minimum lateral offset from the curb face. lateral location of the objects remained unchanged, resulting in an effective lateral offset that was often less than 0.6 m (2 ft). Objects Placed Inappropriately Two of the corridors depicted in Table 14 consistently included in the Sidewalk Buffer Treatment cluster crashes at these turn-lane configurations. In addition, crashes at many of the other corridor sites occurred periodi- The placement of roadside objects immediately adjacent cally (but not always in clusters) at similar turn-lane locations. to active travel lanes at some corridor sites increased when This observation suggests that increased lateral offsets should a sidewalk was physically separated from the curb by a Table 20. Lateral distance to objects that were hit for corridors with curb only. Lateral Speed Limit km/h (mph) Distance 40 48 56 64 72 80 89 Cumulative m (ft) (25) (30) (35) (40) (45) (50) (55) Total Percent Percent 03 0 35 71 2 19 1 1 129 28.3 28.3 (01) 37 2 29 44 16 50 13 3 157 34.4 62.7 (12) 713 0 26 27 2 30 2 3 90 19.7 82.5 (24) 1320 1 6 23 2 18 0 0 50 11.0 93.4 (46) 2026 0 3 10 1 9 0 0 23 5.0 98.5 (68) 2633 0 3 1 2 0 0 0 6 1.3 99.8 (810) 3349 0 0 0 0 0 0 1 1 0.2 100 (1015) 4966 0 0 0 0 0 0 0 0 0.0 100 (1520) Total: 3 102 176 25 126 16 8 456 100

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44 Photo by Karen Dixon. Figure 18. Pole placed at lane merge. buffer strip that contained fixed objects. Interestingly, white line is often not included at locations with a curb as the crashes varied dramatically at these locations. At locations curb itself functions to delineate the edge of the road. During with buffer strips 0.9 m (3 ft) wide or narrower, objects nighttime or inclement weather conditions, the need for were systematically hit. Wider buffer strips containing ma- positive guidance along the right edge of the road may be ture trees with large-diameter trunks placed within 0.9 to heightened due to reduced visibility. In addition, impaired or 1.2 m (3 to 4 ft) of the curb showed a significant increase in fatigued drivers may depend more heavily on this delineation the number of severe crashes with the trees. At locations to help them keep their vehicle within the boundaries of the with smaller, ornamental trees located in the center of a travelway. For a few of the observed corridors, a continuous buffer strip, the number of severe crashes into trees was white line occurred either at the edge of the gutter pan or a few dramatically reduced. By contrast, utility poles and light feet from the gutter pan to delineate a separate bicycle lane. standards were frequently hit at locations where these When this white line was not present, single-vehicle crashes objects were placed in the center of the buffer strip. At sev- tended to occur more frequently at driveway locations. In par- eral sites, however, the research team observed smaller, ticular, objects positioned on the far side of driveways were hit more forgiving objects, such as landscaping with small- more often than objects located away from driveways or caliper trees, positioned near the center of the buffer strip objects that were located on the near side of driveways. This and the more rigid poles and light standards positioned observation is not a surprise because the curb line may no immediately adjacent to the sidewalk and as far from the longer provide positive guidance to vehicles at driveway active travel lane as possible. The crash analysis at these entry points, and the driveway configuration certainly does staggered-object-placement buffer strips showed very few not provide a re-direction function when a vehicle drifts roadside crashes. from the road. Figure 20 shows an example crash location This research suggests that the placement of rigid objects with a pole located at the far side of a driveway. The place- on sidewalk buffer strips 1.2 m (4 ft) wide or narrower ment of the pole within the sidewalk is, of course, also not should be avoided. For wider buffer strips, placement of the recommended. more forgiving roadside items close to the road and place- Of the 456 pole/post/light crashes that occurred at loca- ment of the more rigid objects at a greater lateral offset of tions with curb (see Table 20), 181 occurred at driveways, 1.2 m (4 ft) or more from the curb face is recommended. so this location accounted for approximately 40 percent of all Figure 19 depicts recommended buffer strip object place- of these crashes. Of the 181 driveway-associated, fixed-object ment scenarios. crashes, 155 occurred at locations with no supplemental positive guidance such as a white edge line, approximately 86 percent of these crashes. This percentage of the crashes Driveways Interrupt Positive Guidance/Objects associated with driveways that did not provide additional Placed Near Driveways positive guidance could simply be an artifact of how many Many rural roads have a white edge line delineating the right sites did not have an edge line, but this high a number of edge of the travelway. In urban environments, a continuous crashes certainly warrants future research. Regardless, avoiding

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45 Curb Width Approx. 6" Buffer Strip Width > 4' Frangible Object near Curb Face Center of Buffer Strip 4' minimum from Curb Face to Impact Surface of Rigid Object Adjacent Lane Sidewalk Landscape and Rigid Object Placement for Buffer Strip Widths > 4' Curb Width Approx. 6" Buffer Strip Width < 4' Frangible Objects Only Curb Face in Buffer Strip Region Rigid Objects Placed on Far Side of Sidewalk Adjacent Lane Sidewalk Landscape and Rigid Object Placement for Buffer Strip Widths 4' Figure 19. Object placement at buffer strips. the placement of poles on the immediate far side of some cases, the crash occurred because a driver attempted to driveways will help to reduce the number of crashes. It is avoid hitting another vehicle; however, several single-vehicle important to remember that placing poles on the immediate crashes were also observed at intersection locations. In gen- far side of a driveway may sometimes be the result of trying eral, these single-vehicle, fixed-object crashes at intersections to avoid putting an object on the near side of the driveway in fell into one of the following three categories: the visibility triangle for drivers of vehicles exiting the drive- way, so relocation of the pole should avoid this critical loca- Impacted small channelization islands (often these is- tion as well. lands included signs, traffic signals, or poles). This inter- section crash type occurred at six of the study corridors (see Table 14). Three Kinds of Fixed-Object Placement Impacted objects positioned close to the lane edge. These at Intersections objects often interfered with turning movements when Crashes at intersections often occur between vehicles; vehicles veered from their turning path. however, several intersection crashes in which vehicles hit Impacted objects where pedestrian ramps at intersection roadside objects were also noted in the corridor analysis. In corners were oriented in such a way as to direct errant