Communicating Changes in Horizontal Alignment (2006)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

20 CHAPTER 4 PRACTITIONER OPINION ON PROPOSED MUTCD CHANGES INTRODUCTION The final task was to query practitioners regarding their views on the proposed changes to the MUTCD presented in the previous chapter. The same mailing lists used for the initial practitioner survey were used again with the addition of the members of a subcommittee of the National Commit- tee on Uniform Traffic Control Devices (the national com- mittee). As was the procedure for the first practitioner survey, this survey was distributed by regular mail and by e-mail. Overall, approximately 1,100 surveys were distributed although some copies were circulated and forwarded within an agency, so a total n is unknown. From these, 144 usable responses were obtained. There were 66 responses from state-level agencies, 61 from the county level, and 11 from other jurisdictions. The latter are typically not included in results presented here. There were also 9 responses from members of the national committee. While the input from the national committee is important, the sample size regarding any given question is quite small (9 or fewer). For example, a shift in one respondent results in a “percentage change” of 11%—a 5-to-4 response that changes to 4-to-5 results in a change from 55.5% favoring to 44.4%. Thus, in the discus- sion that follows, more weight is given to the practitioners’ opinions. FINAL PRACTITIONER SURVEY RESULTS The responses to the key questions are provided in tables below along with a discussion and any comments that were made. First Recommendation (Changing “May” to “Should” Regarding Use of Basic Curve Signs) The text of the first recommendation and the results re- garding “adoption” are shown in Table 2. This recommen- dation is intended to increase uniformity in the application of the basic horizontal alignment signs by changing “may” to “should.” As can be seen, support is fairly strong for adopt- ing this change (about 2/3 to 1/3) although it is less so from the national committee members. Note, however, that the sam- ple size for the latter is small. At the same time, there is very little support for making the condition even stronger by mov- ing to a “shall” condition. The support for the stronger but not strongest language is consistent with what practitioners indicated in the focus groups and earlier survey. They are interested in more consistency and stronger guidelines but within limits as they do not want “guidance” to result in mandatory changes. It is also interesting to note that support is strong regard- less of whether it is measured at the state or local (county) level although support from the state-level respondents was stronger. This may be because the signs are more likely to already be deployed on the state-level portions of the system and because the change is more a reflection of what is already being used in the field. Respondents were also asked about significant problems associated with the adoption of the first recommendation, specifically related to cost and liability. Overall, only about one-quarter of the respondents thought that cost would be a problem—less than 20% of state-level respondents and about a third of county-level practitioners. Liability was perceived to be more problematic with ∼35% of all respondents indi- cating that it would be an issue. Again, there was some dif- ference between state and county-level practitioners with 29% of the former and ∼38% of the latter thinking that liability would be an issue. The comments from the respondents were also interesting. Of those responding, ∼25% thought cost would be problem with about 42% making additional comments about cost. These figures increased to ∼35% and ∼42%, respectively, when lia- bility was the question. Regarding comments on “cost,” there was a significant range of issues mentioned. On the “positive” side, several indicated that the “may” is already effectively interpreted as “should” in their jurisdiction and, thus, there would be no cost impact. On the “negative” side, other re- spondents indicated that it would mean more signs and addi- tional cost unless lower-volume roads were exempted. One respondent indicated that this was akin to “another unfunded federal mandate.” However, since the MUTCD has a sepa- rate section for low-volume roads, these comments may have resulted from the respondent’s taking the recommendation out of the intended context. In the comments, there seemed to be general agreement that cost impacts would more likely be felt at the local level rather than state level. Several respon-

dents were concerned about how this would impact moun- tainous states or mountainous areas within a state—the im- plication being that the change would have a greater impact in those situations. Concerns about liability, in addition to being more numer- ous, were also more extensive. Some respondents essentially argued that “may” and “should” are both recommendations and that liability increases only when a sign is required, but not used. Another respondent noted that “should” had already been interpreted by the state attorney general’s office as a “standard” that could result in “unlimited liability” for the DOT. There were essentially two perspectives on liability issues: while many thought that the changes were appropriate and the “right” thing to do, many others commented that lia- bility would almost assuredly be increased. It was also clear that liability varied significantly from one state to another: one respondent noted that courts were currently very protective of the jurisdictions’ actions with respect to TCD placement while another, as noted earlier, interpreted the word “should” as a rule with deviation being grounds for liability. So, while the majority of respondents thought the change should be made (if it had not operationally been made already) and did not see severe problems with it, a minority believe they could suffer significantly increased liability. Comments regarding making the language even more strin- gent (“may” to “shall”) were more emphatically negative. Typical comments included more problems with cost, far 21 more problems with liability, and the elimination of engi- neering judgment. One respondent indicated that “it would take the ‘engineering’ out of the traffic engineering business.” Second Recommendation (Use of Advisory Speed Plaques) With reference to Table 3 for text and results, support for the second recommendation—which is intended to increase uniformity in the application of advisory speed plaques—is also supported by respondents at about the same levels as the first recommendation. Just under half of all respondents thought that the criterion for using speed advisories should be when the advisory speed would be ∼10 mph under the speed limit. Approximately two-thirds of all respondents thought that the threshold speed should be 10 mph or less under the speed limit. Although the sample size was small, the national committee members were about twice as likely to favor a lower threshold of 5 mph. Somewhat surprisingly, there were only a few comments, and they were mixed—for example, define X or options should always use “may.” Third Recommendation (Engineering Study) Although the requirement for the use of an “engineering study” is cited in the MUTCD, the term is not adequately First recommendation: The first option in §2C.06 of the millennium edition of the MUTCD should be changed to read that horizontal alignment signs may be used in advance of situations where the roadway alignment changes and should be used when the alignment change would result in an advisory speed equal to or lower than the posted speed limit. The Winding Road (W1-5) sign should be used where there is a series of turns or curves that requires driving caution and where curve or turn signs would be too numerous to be effective. Where any of the curves has an advisory speed that is (x) mph or more below that of the first curve, then a curve or turn warning sign and an advisory speed plaque should be used. Employer Overall Guideline Questions Answer county road commission (n=61) state highway department (n=66) national committee members (n=9) yes 60.7* 74.2 55.6 Do you believe the changes from may to should in the first recommendation should be adopted? no 39.3 25.8 44.4 (n=33) (n=45) (n=5) yes 12.1 6.7 0 Should the changes be even more emphatic, to shall? (i.e., be shall rather than should?) no 87.9 93.3 100 *All entries are percentages of total respondents. TABLE 2 Support for the first recommendation

defined in the specific context of horizontal curves. This is in contrast to the provisions in other sections of the MUTCD, which are explicit. One example is §2B.13 of the 2003 MUTCD, which provides factors to consider when setting speed limits. To that end, the third recommendation was in- tended to increase uniformity in the use of an engineering study by defining the term, at least in the context of horizon- tal curves. Basic results are shown in Table 4. Both state and local practitioners supported this recommen- dation (just greater than 60% of the respondents) although not quite as strongly as they did the first two recommendations. A majority of the respondents from the national committee did not support the third recommendation, although the sample size is small. Respondents were also asked to indicate which factors should be added or eliminated, if any. While comments per se were not solicited on the basic question, about 10% of the respondents made one anyway. The comments were generally negative: “too cumbersome, confusing, and nebulous”; “engineers [already] know what to consider”; “not appropriate for MUTCD but perhaps the TCD Handbook”; and “didn’t like the list presented.” Table 5 is an overview of what the respondents thought about the adequacy of the list of study factors. Just less than 22 half thought that the list was adequate “as is” with the rest desiring to modify the list in some way—primarily by adding factors. Table 6 is the distribution of responses to a follow-up question regarding the factors that should be included in an engineering study to determine the appropriate TCDs for horizontal curves. As noted in Table 6, there is some dis- agreement in terms of what an appropriate study might in- clude. The factors listed are interesting from several perspec- tives. While some such as consideration of the accident history make sense, the relative number of respondents who single out 85th-percentile speeds to be disregarded or at least dis- counted is somewhat alarming, especially in conjunction with the number who believe that continued emphasis should be placed on the ball-bank indicator. The latter was without any reference to interpreting the readings. Several respondents also mentioned the need for research in using the ball-bank indicator. Fourth Recommendation (Expert System) The fourth (or “other”) recommendation was to develop an “expert system” that could be used to provide guidance on Second recommendation: MUTCD §2C.42 should be changed to read as follows: An Advisory Speed (W13-1) plaque should be used to indicate the advisory speed for a change in horizontal alignment when the advisory speed is X mph or more below the applicable speed limit. Employer Overall Guideline Questions Answer county road commission (n=61) state highway department (n=66) national committee members (n=9) yes 63.9* 77.3 55.6 Do you believe the change from may to should in the second recommendation should be adopted? no 36.1 22.7 44.4 (n=57) (n=61) (n=5) 0 1.8 3.3 0.0 5 21.1 34.4 50.0 10 45.6 45.9 37.5 >10 26.3 14.8 12.5 If the second recommendation is adopted, what value of X should be specified? other 5.2 1.6 0.0 *All entries are percentages of total respondents. TABLE 3 Support for the second recommendation

23 Third recommendation: Add a section to the MUTCD (similar to §2B.11 for setting speed limits in speed zones) to define the factors to be considered when conducting an engineering study to establish the appropriate TCDs when there is a change in the horizontal alignment of the highway. The language should read as follows: Standard: After an engineering study has been made in accordance with established traffic engineering practice or where engineering judgment determines the need for horizontal alignment signs, advisory speed plaques, and/or supplemental guidance, these TCDs shall be used. Guidance: The factors that should be considered in determining the system of TCDs to be displayed when there is a change in the horizontal alignment of the highway include • The difference in the posted speed limit and the 85th-percentile speed of free-flowing traffic; • The approach sight distance to the beginning of the curve; • The visibility around the curve; • Unexpected geometric features within the curve, such as an intersection or a change in the curve radius; and • The position of the most critical curve in a sequence of relatively closely spaced curves. Employer Overall Guideline Question Answer county road commission (n=60) state highway department (n=65) national committee members (n=8) yes 61.7* 61.5 37.5 Do you believe the third recommendation defining elements to be included in an engineering study for TCD application at horizontal curves should be adopted? no 38.3 38.5 62.5 *All entries are percentages of total respondents. If answered “yes” regarding adoption of a recommendation for an engineering study for TCD applications at horizontal curves, is the list of factors sufficient? Employer Possible Responses county road commission (n=37) * state highway department (n=42) national committee members (n=4) list in recommendation is sufficient 51.4 42.9 25.0 add factors 32.4 38.1 50.0 eliminate factors 5.4 7.1 25.0 both add and eliminate factors 10.8 11.9 0.0 *All entries are percentages of total respondents answering “yes” or providing suggestions. TABLE 5 Adequacy of study factors listed in the third recommendation TABLE 4 Support for the third recommendation

advisory speeds. As shown in Table 7, support for this rec- ommendation fell below a majority for all respondents. There may be some clues for the lack of support in the (12) comments that respondents offered. First, some respondents are not aware of the capabilities of an expert system or how one works. This is clear from comments such as “do not understand what an ‘expert system’ would be or what it would achieve” and “ball-bank indicators are already avail- able and have been used extensively for this purpose.” Other- wise, some respondents worried that use of such a system 24 becomes too prescriptive or that the discretion encompassed in the term “engineering judgment” is compromised. A typi- cal comment was that “engineers should determine sign instal- lations.” Still others, who made comments such as “not as part of MUTCD,” did not understand its relationship to the MUTCD. Obviously, if such a system is developed, it will have to be accompanied by extensive “marketing” so that end users know what it is and how to use it. However, the danger exists for such systems to be used as a “black box” by un- sophisticated users. Number of Respondents Concurring Factors 5 factors in Guideline 3 sufficient add to 5 factors eliminate from 5 factors the difference in the posted speed limit and the 85th-percentile speed of free-flowing traffic 37* — 2 85th-percentile (part of above, but listed separately as several wanted to eliminate reference to this speed) — — 5 the approach sight distance to the beginning of the curve 37 — 3 the visibility around the curve 37 — 3 unexpected geometric features within the curve, such as an intersection or a change in the curve radius 37 — 1 the position of the most critical curve in a sequence of relatively closely spaced curves 37 — 2 shoulder width — 2 — shoulder type — 1 — obstruction close to pavement — 1 — gradient — 2 — ball-bank study — 5 — ball-bank study using 10° — 1 — electronic ball-bank study — 1 — 85th-percentile speed of vehicles in curve — 1 — accident history — 7 — superelevation — 1 — roadway volume or average daily traffic — 3 — signing practices in area — 1 — degree of curvature — 1 — TABLE 6 Factors suggested for inclusion in horizontal curve study

25 length of curve — 1 — correlation to no-passing zone — 1 — vertical alignment — 2 — curve advisory speed — 1 — overall alignment characteristics of segment — 1 — surface conditions — 2 — road/lane width — 2 — guardrail — 1 — curve widening — 1 — roadside hazards — 1 — number of respondents not supportive of the third recommendation 48 *Note that 77 respondents were in favor of Guideline 3. Of those, 37 responded that the list of factors was sufficient; the rest suggested one or more additions and/or deletions from the list. Fourth Recommendation: NCHRP should consider funding a project to incorporate these factors in an expert system similar to the U.S. Limits system being developed to provide guidance on the speed limit to be posted in speed zones. Employer Overall Guideline Questions Answer county road commission (n=58) * state highway department (n=62) national committee members (n=9) yes 44.8 46.8 22.2 Do you believe the fourth recommendation regarding the development of an expert system should be pursued? no 55.2 53.2 77.8 *All entries are percentages of total respondents. TABLE 7 Support for the fourth recommendation TABLE 6 (Continued)