Trade-Off Considerations in Highway Geometric Design (2011) / Chapter Skim
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From page 92... ...
90 APPENDIX B Summary of STA Survey Responses Overview Question 1. Do trade-off considerations ever enter into the process for geometric design decisions at your STA?
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91 • Deviations are handled at the regional level requiring only the Region Preconstruction Engineer's signature. Both design exceptions and waivers require the design exception form be filled out completely with supporting information as needed.
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92 • There is no such process. Tradeoffs, as they are called in this study, are done as part of the normal design of each project -- as they have been done for decades.
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93 • The goal is to add value to the projects during all phases of the project development. Design decisions are preferably handled in the earlier stages of project development, but can be incorporated in the later stages as well.
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94 • Deputy Chief Engineer grants some design approvals, and approves design exceptions for those same projects. • Design exception approval • Design Exception approval • Design exception approval has delegated to District Engineers • Design exception approval.
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95 • Legal. Typically not involved in design.
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96 • Is involved in the design exception approval • Makes sure that plans and documents are complete, Project scope will be met and that specifications are followed, attends field checks, makes sure that the project activities are on schedule for each milestone, updates the project schedule with respect to its progress and the rate of plan development if necessary. • Manage design of projects • oversees project development and production, documentation and leads public involvement process • PM -- Sign off on designer's form • Prepares the Design Exception for the Design Chief's approval.
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97 • Identification and initial assessment of trade-offs • Interactive support of design activities. • none • Not involved with design • Not involved with design.
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98 • None • None • None. • Not involved • Not involved in design or project development.
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99 9. What type of trade-off is most typically used as a justification for a design decision?
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100 All Responses Access Management 2 Cost 29 Environmental Issue 24 Historic Impact 5 Human Factor/Driver Expectancy 4 Operational Efficiency 12 Right-of-Way Availability 10 Safety 28 Schedule 6 Social Concerns 2 Tort Liability Exposure 4 10. Please indicate on a scale of 1 to 10 how likely your agency is to consider a listed trade-off as a reason for accepting a design decision, with 10 being very likely and 1 being not likely?
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101 Environmental Issue – Average 8.1 0 Not Likely 1 1 2 1 3 1 4 0 5 3 6 5 7 12 8 12 9 6 10 Very Likely Historic Impact – Average 7.7 1 Not Likely 1 0 2 2 3 0 4 1 5 2 6 6 7 14 8 8 9 6 10 Very Likely Human Factors/Driver Expectancy – Average 6.5 0 Not Likely 1 1 2 2 3 5 4 8 5 2 6 9 7 6 8 6 9 2 10 Very Likely
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102 Operational Efficiency – Average 7.3 1 Not Likely 1 0 2 3 3 1 4 2 5 3 6 10 7 9 8 8 9 4 10 Very Likely Right-of-Way Availability – Average 6.8 0 Not Likely 1 0 2 4 3 2 4 6 5 6 6 6 7 6 8 7 9 4 10 Very Likely Safety – Average 8.1 3 Not Likely 1 1 2 0 3 1 4 1 5 1 6 5 7 2 8 7 9 19 10 Very Likely
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103 Schedule – Average 5.7 0 Not Likely 1 7 2 4 3 6 4 1 5 7 6 3 7 4 8 3 9 6 10 Very Likely Social Concerns – Average 5.9 0 Not Likely 1 0 2 7 3 8 4 4 5 3 6 10 7 3 8 2 9 4 10 Very Likely Tort Liability Concerns – Average 5.3 5 Not Likely 1 3 2 3 3 5 4 8 5 2 6 3 7 5 8 4 9 3 10 Very Likely 11. What methodology, if any, is typically utilized to measure each of the listed trade-offs?
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104 • Evaluating the existing access regulations against existing conditions and usage. • Evaluation of operational efficiency, review of type and number of crashes.
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105 • Comparison with cost of meeting standards, construction costs compared to environmental mitigation costs, right-of-way and utility costs. • Cost analysis • Cost Analysis, general based on expertise and detailed analysis where needed, based on the judgment of the engineers.
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106 • Evaluation of impacts • Expert opinion • Expert Opinion • expert opinion, SCDOT and Federal policies/procedures/guidelines, shareholder input • Expert opinion, state regulation • Federal & State Regulations • Federal Regulation • Federal regulations, Expert Opinion • Federal regulations. • Federal/state regulations • In most cases we don't have a formal system for making those evaluations.
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107 struction or widening of an existing highway facility. However, from the perspective of horizontal and vertical alignment, much of this impact can and should be alleviated.
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108 • Expert opinion • Expert Opinion • Expert Opinion • Expert Opinion • expert opinion, SCDOT and Federal policies/procedures/guidelines • Expert opinion, state regulation • Expert opinion, Traffic anal., B/C anal. IHSDM • Expert opinion, traffic analysis, highway capacity manual.
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109 • Engineering judgment • Engineering operational analysis/capacity analysis • Evaluation of the design • expert opinion • Expert opinion • Expert opinion • Expert Opinion • Expert Opinion • Expert opinion and calculated LOS • expert opinion, modeling • expert opinion, SCDOT and Federal policies/procedures/guidelines • Expert opinion, state regulation • HCM • HCM and expert opinion • Highway Capacity Manual • Highway Capacity Manual, other • Level of Service • Modeling of the operational characteristics is done to determine capacity needs and congestion issues. Anticipated future growth is also considered.
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110 • expert opinion • Expert opinion • expert opinion, SCDOT and Federal policies/procedures/guidelines, shareholder input • Expert opinion, state regulation • INDOT project Manager or project engineer will make enquiry and communicate with the right-of-way cost estimator in order to provide input on probable design scenarios that will impact the right-of-way requirements and cost, and the potential trade-offs between right-of-way and design may be discussed. The estimator's experience and knowledge of the area are very important in establishing a preliminary right-of-way cost.
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111 • Expert opinion, design criteria, Traffic anal. State and Fed.
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112 • On occasion projects have critical Advertising dates to meet funding years. ROW/Utilities can be difficult to acquire in a short time frame, so design exceptions are chosen to ensure that projects meet advertising deadlines.
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113 The Indiana State Department of Transportation (INDOT) defines the Context Sensitive Design approach to project development as the way it does business for all highway projects.
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114 • Legal counsel • Legal counsel, State and Fed. Regs., Expert opinion • Legal counsel.
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115 • Design decisions are documented through Scoping Reports as well as the use of project files. Informally the design decisions are documented through emails.
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116 should contain. The final plan checking process reviews the design decisions to ensure proper documentation and to ensure that the design elements have been included in the plans.
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117 • The Department's intent is that all design criteria described in the State and federal regulations, manuals and guidelines be satisfied. If practical, the proposed design should exceed the minimum or lower criteria.
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118 is paramount because it is at this point we (INDOT) can present a greater level of detail rather than just concepts and illustrate visually the proposal at hand, garnering tangible feedback from the public, in addition to describing impacts.
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119 • N/A • Newsletters, websites and other published project information • Press releases, public meetings, letters • Primarily documented through hearings, public meetings and the environmental process. • Public hearings, public meetings, project newsletters • Public information meetings • Public Information meetings.
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120 • Need to establish more detailed protocol and set up better documentation process. Currently, designers are encouraged to follow a process; however there is no process that is required to be followed unless the issue requires a design exception.
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121 • More than one engineer is involved in the trade-offs evaluations • Multiple reviews by many divisions and agencies provide adequate checks and balances. • New attention has been focused in this area and approval by Office of Design Director encourages consistency.
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122 • The project team process involves most or all of the stakeholders. • We have well defined processes for design exceptions, waivers and deviations.
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123 • The Department's hardest weaknesses in respect to the design selection process relative to evaluating trade-offs can be found in: – Engineering economic analysis is the classical means for assessing trade-offs in a highway-project. Comparison of road-user benefits against project costs, incorporating money's time value, is the essence of engineering economic analysis.
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124 With the expanding role of public involvement and the push to address concerns beyond engineering in highway projects come added responsibilities and considerations. Today, highway designers face many complex tradeoffs.
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125 informed decisions about projects and design choices. Mn/DOT believes that Risk Management is not only a tool and process, but a language and academic field that can drive productive conflict, progress, and management of risks at multiple levels of government.
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126 • For vertical clearance. Using engineering judgment and experience the chances of an accident occurring is unlikely, if there is an accident there are great risks involved.
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127 • Unacceptable risk would be any trade-off that resulted in an anticipated hazardous condition on the roadway. We have not utilized risk analysis to assess schedule and budget creep.
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128 21. If your STA does have risk prediction tools or techniques, are they 1 Quantitative 3 Qualitative 11 Both 25 None Tools and Training 22.
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129 • 3 day geometric/design exception class • But we are developing some especially when it comes to Exceptions. • CDOT has the Transportation Engineering Training Academy program.
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130 mately $200 million in federal-aid funding available every year, the MPOs play a large part in Indiana's metropolitan transportation picture. – As part of the department's efforts to increase knowledge about the Local Public Agency (LPA)
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131 • No specific projects.
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132 27. How many of these design exceptions are approved in a typical year?
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133 • To date we haven't had an increase in exceptions for true context sensitive issues -- we have had an increase in design exceptions to reduce right-of-way impacts, but the context is almost exclusively cost based. • We have incorporated these into our process years ago.
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From page 136... ...
134 Third Greatest Number of Requests Design Speed 2 Lane Width 3 Shoulder Width 8 Bridge Width 1 Structural Capacity 0 Horizontal Alignment 4 Vertical Alignment 8 Grade 4 Stopping Sight Distance 1 Cross Slope 0 Superelevation 2 Vertical Clearance 3 Horizontal Clearance 2 All Responses Design Speed 5 Lane Width 10 Shoulder Width 34 Bridge Width 4 Structural Capacity 0 Horizontal Alignment 16 Vertical Alignment 15 Grade 8 Stopping Sight Distance 4 Cross Slope 3 Superelevation 5 Vertical Clearance 6 Horizontal Clearance 4 30. Please indicate on a scale of 1 to 10 how willing your agency typically is to consider a design exception for a particular controlling criteria, with 10 being very likely to consider a design exception for the listed criteria and 1 being not likely to consider a design exception for the listed criteria.
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135 Lane Width – Average 6.2 0 Not Likely 1 2 2 4 3 3 4 5 5 5 6 4 7 13 8 2 9 1 10 Very Likely Shoulder Width – Average 7.7 0 Not Likely 1 0 2 1 3 1 4 4 5 2 6 9 7 4 8 12 9 6 10 Very Likely Bridge Width – Average 5.5 1 Not Likely 1 4 2 5 3 4 4 6 5 3 6 6 7 6 8 2 9 2 10 Very Likely Structural Capacity – Average 2.0 24 Not Likely 1 5 2 5 3 1 4 2 5 0 6 2 7 0 8 0 9 0 10 Very Likely
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136 Horizontal Alignment – Average 5.7 1 Not Likely 1 4 2 3 3 2 4 4 5 10 6 8 7 3 8 3 9 1 10 Very Likely Vertical Alignment – Average 6.4 2 Not Likely 1 1 2 2 3 3 4 4 5 6 6 6 7 6 8 7 9 2 10 Very Likely Grade – Average 6.1 0 Not Likely 1 2 2 3 3 4 4 5 5 9 6 6 7 4 8 4 9 2 10 Very Likely Stopping Sight Distance – Average 4.5 3 Not Likely 1 4 2 11 3 3 4 6 5 2 6 6 7 3 8 0 9 1 10 Very Likely
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From page 139... ...
137 Cross Slope – Average 5.4 1 Not Likely 1 5 2 2 3 5 4 4 5 8 6 7 7 5 8 2 9 0 10 Very Likely Superelevation – Average 5.5 1 Not Likely 1 4 2 2 3 3 4 7 5 7 6 8 7 7 8 0 9 0 10 Very Likely Vertical Clearance – Average 4.5 6 Not Likely 1 5 2 5 3 4 4 5 5 1 6 8 7 3 8 1 9 1 10 Very Likely Horizontal Clearance – Average 5.2 3 Not Likely 1 4 2 3 3 4 4 6 5 4 6 8 7 6 8 1 9 0 10 Very Likely
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From page 140... ...
138 31. For each of the controlling criteria listed, is your STA's criteria for new construction and reconstruction higher than AASHTO's (check one for each)
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From page 141... ...
139 All Responses Access Management 2 Cost 11 Environmental Issue 6 Historic Impact 2 Human Factors/Driver Expectancy 6 Operational Efficiency 6 Right-of-Way Availability 9 Safety 11 Schedule 0 Social Concerns 4 Tort Liability Exposure 0 Lane Width Most Common Trade-Off Access Management 0 Cost 7 Environmental Issue 3 Historic Impact 2 Human Factors/Driver Expectancy 1 Operational Efficiency 2 Right-of-Way Availability 16 Safety 5 Schedule 0 Social Concerns 1 Tort Liability Exposure 1 Next Most Common Trade-Off Access Management 1 Cost 9 Environmental Issue 5 Historic Impact 1 Human Factors/Driver Expectancy 6 Operational Efficiency 2 Right-of-Way Availability 10 Safety 2 Schedule 1 Social Concerns 1 Tort Liability Exposure 0
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140 All Responses Access Management 1 Cost 16 Environmental Issue 8 Historic Impact 3 Human Factors/Driver Expectancy 7 Operational Efficiency 4 Right-of-Way Availability 26 Safety 7 Schedule 1 Social Concerns 2 Tort Liability Exposure 1 Shoulder Width Most Common Trade-Off Access Management 0 Cost 10 Environmental Issue 4 Historic Impact 1 Human Factors/Driver Expectancy 2 Operational Efficiency 0 Right-of-Way Availability 16 Safety 5 Schedule 0 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 8 Environmental Issue 7 Historic Impact 1 Human Factors/Driver Expectancy 2 Operational Efficiency 1 Right-of-Way Availability 11 Safety 6 Schedule 1 Social Concerns 1 Tort Liability Exposure 0
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141 All Responses Access Management 0 Cost 18 Environmental Issue 11 Historic Impact 2 Human Factors/Driver Expectancy 4 Operational Efficiency 1 Right-of-Way Availability 27 Safety 11 Schedule 1 Social Concerns 1 Tort Liability Exposure 0 Bridge Width Most Common Trade-Off Access Management 0 Cost 24 Environmental Issue 2 Historic Impact 3 Human Factors/Driver Expectancy 0 Operational Efficiency 0 Right-of-Way Availability 1 Safety 7 Schedule 0 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 8 Environmental Issue 8 Historic Impact 1 Human Factors/Driver Expectancy 2 Operational Efficiency 3 Right-of-Way Availability 6 Safety 6 Schedule 1 Social Concerns 2 Tort Liability Exposure 0
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From page 144... ...
142 All Responses Access Management 0 Cost 32 Environmental Issue 10 Historic Impact 4 Human Factors/Driver Expectancy 2 Operational Efficiency 3 Right-of-Way Availability 7 Safety 13 Schedule 1 Social Concerns 2 Tort Liability Exposure 0 Structural Capacity Most Common Trade-Off Access Management 1 Cost 10 Environmental Issue 2 Historic Impact 1 Human Factors/Driver Expectancy 0 Operational Efficiency 0 Right-of-Way Availability 1 Safety 10 Schedule 1 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 8 Environmental Issue 3 Historic Impact 2 Human Factors/Driver Expectancy 0 Operational Efficiency 4 Right-of-Way Availability 1 Safety 2 Schedule 2 Social Concerns 1 Tort Liability Exposure 3
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143 All Responses Access Management 1 Cost 18 Environmental Issue 5 Historic Impact 3 Human Factors/Driver Expectancy 0 Operational Efficiency 4 Right-of-Way Availability 2 Safety 12 Schedule 3 Social Concerns 1 Tort Liability Exposure 3 Horizontal Alignment Most Common Trade-Off Access Management 0 Cost 10 Environmental Issue 4 Historic Impact 1 Human Factors/Driver Expectancy 0 Operational Efficiency 2 Right-of-Way Availability 14 Safety 5 Schedule 0 Social Concerns 1 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 6 Environmental Issue 4 Historic Impact 1 Human Factors/Driver Expectancy 4 Operational Efficiency 0 Right-of-Way Availability 7 Safety 11 Schedule 1 Social Concerns 2 Tort Liability Exposure 1
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144 All Responses Access Management 0 Cost 16 Environmental Issue 8 Historic Impact 2 Human Factors/Driver Expectancy 4 Operational Efficiency 2 Right-of-Way Availability 21 Safety 16 Schedule 1 Social Concerns 3 Tort Liability Exposure 0 Vertical Alignment Most Common Trade-Off Access Management 0 Cost 14 Environmental Issue 3 Historic Impact 1 Human Factors/Driver Expectancy 0 Operational Efficiency 2 Right-of-Way Availability 8 Safety 8 Schedule 0 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 5 Environmental Issue 6 Historic Impact 1 Human Factors/Driver Expectancy 8 Operational Efficiency 0 Right-of-Way Availability 4 Safety 10 Schedule 1 Social Concerns 1 Tort Liability Exposure 0
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From page 147... ...
145 All Responses Access Management 0 Cost 19 Environmental Issue 9 Historic Impact 2 Human Factors/Driver Expectancy 8 Operational Efficiency 2 Right-of-Way Availability 12 Safety 18 Schedule 1 Social Concerns 1 Tort Liability Exposure 0 Grade Most Common Trade-Off Access Management 0 Cost 16 Environmental Issue 3 Historic Impact 2 Human Factors/Driver Expectancy 2 Operational Efficiency 4 Right-of-Way Availability 4 Safety 6 Schedule 0 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 7 Environmental Issue 5 Historic Impact 1 Human Factors/Driver Expectancy 4 Operational Efficiency 3 Right-of-Way Availability 8 Safety 7 Schedule 1 Social Concerns 1 Tort Liability Exposure 0
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From page 148... ...
146 All Responses Access Management 0 Cost 23 Environmental Issue 8 Historic Impact 3 Human Factors/Driver Expectancy 6 Operational Efficiency 7 Right-of-Way Availability 12 Safety 13 Schedule 1 Social Concerns 1 Tort Liability Exposure 0 Stopping Sight Distance Most Common Trade-Off Access Management 0 Cost 7 Environmental Issue 1 Historic Impact 2 Human Factors/Driver Expectancy 1 Operational Efficiency 1 Right-of-Way Availability 4 Safety 22 Schedule 0 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 7 Environmental Issue 3 Historic Impact 2 Human Factors/Driver Expectancy 7 Operational Efficiency 4 Right-of-Way Availability 7 Safety 2 Schedule 0 Social Concerns 1 Tort Liability Exposure 4
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From page 149... ...
147 All Responses Access Management 0 Cost 14 Environmental Issue 4 Historic Impact 4 Human Factors/Driver Expectancy 8 Operational Efficiency 5 Right-of-Way Availability 11 Safety 24 Schedule 0 Social Concerns 1 Tort Liability Exposure 4 Cross Slope Most Common Trade-Off Access Management 0 Cost 10 Environmental Issue 3 Historic Impact 1 Human Factors/Driver Expectancy 3 Operational Efficiency 3 Right-of-Way Availability 3 Safety 14 Schedule 0 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 1 Cost 9 Environmental Issue 3 Historic Impact 1 Human Factors/Driver Expectancy 2 Operational Efficiency 4 Right-of-Way Availability 3 Safety 7 Schedule 2 Social Concerns 0 Tort Liability Exposure 3
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148 All Responses Access Management 1 Cost 19 Environmental Issue 6 Historic Impact 2 Human Factors/Driver Expectancy 5 Operational Efficiency 7 Right-of-Way Availability 6 Safety 21 Schedule 2 Social Concerns 0 Tort Liability Exposure 3 Superelevation Most Common Trade-Off Access Management 0 Cost 9 Environmental Issue 2 Historic Impact 1 Human Factors/Driver Expectancy 4 Operational Efficiency 2 Right-of-Way Availability 3 Safety 16 Schedule 0 Social Concerns 0 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 1 Cost 7 Environmental Issue 4 Historic Impact 1 Human Factors/Driver Expectancy 5 Operational Efficiency 4 Right-of-Way Availability 4 Safety 6 Schedule 2 Social Concerns 0 Tort Liability Exposure 3
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From page 151... ...
149 All Responses Access Management 1 Cost 16 Environmental Issue 6 Historic Impact 2 Human Factors/Driver Expectancy 9 Operational Efficiency 6 Right-of-Way Availability 6 Safety 22 Schedule 2 Social Concerns 0 Tort Liability Exposure 3 Vertical Clearance Most Common Trade-Off Access Management 0 Cost 23 Environmental Issue 1 Historic Impact 1 Human Factors/Driver Expectancy 1 Operational Efficiency 0 Right-of-Way Availability 1 Safety 8 Schedule 1 Social Concerns 1 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 6 Environmental Issue 3 Historic Impact 2 Human Factors/Driver Expectancy 2 Operational Efficiency 10 Right-of-Way Availability 4 Safety 3 Schedule 1 Social Concerns 2 Tort Liability Exposure 2
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From page 152... ...
150 All Responses Access Management 0 Cost 29 Environmental Issue 4 Historic Impact 3 Human Factors/Driver Expectancy 3 Operational Efficiency 10 Right-of-Way Availability 5 Safety 11 Schedule 2 Social Concerns 3 Tort Liability Exposure 2 Horizontal Clearance Most Common Trade-Off Access Management 0 Cost 13 Environmental Issue 3 Historic Impact 0 Human Factors/Driver Expectancy 1 Operational Efficiency 0 Right-of-Way Availability 6 Safety 10 Schedule 0 Social Concerns 2 Tort Liability Exposure 0 Next Most Common Trade-Off Access Management 0 Cost 10 Environmental Issue 3 Historic Impact 1 Human Factors/Driver Expectancy 2 Operational Efficiency 2 Right-of-Way Availability 7 Safety 7 Schedule 0 Social Concerns 0 Tort Liability Exposure 2
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From page 153... ...
151 All Responses Access Management 0 Cost 23 Environmental Issue 6 Historic Impact 1 Human Factors/Driver Expectancy 3 Operational Efficiency 2 Right-of-Way Availability 13 Safety 17 Schedule 0 Social Concerns 2 Tort Liability Exposure 2 33. Please list the most common mitigation measures utilized for design exceptions of the corresponding criteria.
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From page 154... ...
152 Mitigation Measure Impact on Acceptance of Design Exception 15 More Likely 10 Equally Likely 3 Less Likely Lane Width Most Common Mitigation Measure • Adequate shoulder width to pull a vehicle off, milled shoulder rumble strips • Adjusting speed limit, signing • An assessment of traffic volume and characteristics -- low volumes and low percentage of trucks may enhance the possibility of a design exception. • Better wearing surface, better delineation.
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From page 155... ...
153 • Guardrail • Guardrail • guardrail, horizontal clearance • have used some signing and markings to indicate reduced shoulder • In low-speed urban environments, other design elements fashioned to support lower-speed operation. • Increased Clear Recovery • lack of accident history; low demand for use by bikes or peds • Lighting • Milled shoulder rumble strips, narrow lanes slightly to get adequate width for stalled car, paved shoulder • none • None needed • Object markers, signing • paved shoulders, rumble strips • Provide wider shoulder in some areas • Pull off areas • reduced shoulder width • Reduction of design speed and/or posted speed • Right-of-way • Roadside safety improvements/pavement marking improvements • Rumble strips • Rumble strips, occasional pullouts and guardrails • Signage • Signing • Signing • Signing, reduce speed • Stabilization of shoulder • Stable shoulder, better delineation.
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From page 156... ...
154 • Not available. • Object markers • Rarely applicable -- almost always on 3R situations • Reduce shoulder width • reduced bridge width • Reduction of design speed and/or posted speed • remaining consistent with adjacent highway section • Right-of-way • Safety • Signage; delineator on concrete railings/parapets; upgraded railings • Signing • Signing • Signing • Signing • Signing • Signing, wide load and heavy truck restrictions Mitigation Measure Impact on Acceptance of Design Exception 11 More Likely 15 Equally Likely 2 Less Likely Structural Capacity Most Common Mitigation Measure • Advanced warning for weight limit enforcement • Advanced Warning Signs • Haven't done • n/a • N/A • N/A • N/A • N/A.
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From page 157... ...
155 Mitigation Measure Impact on Acceptance of Design Exception 4 More Likely 10 Equally Likely 4 Less Likely Horizontal Alignment Most Common Mitigation Measure • Advance sign warnings, chevron sign in curves, adjust lane within travelway • Advanced warning per MUTCD • Advanced Warning Signs • advanced warning with signing or pavement markings • Advisory Signing • Advisory speed signing • Advisory speed signing • Chevrons, advisory speed signs • Delineators, reflectors, signing, chevrons • Driver expectancy • Enhanced signing and delineation • Flattening side slopes through the curve, guardrail installation. • improve sight distance, signing, speed reduction • Increase Signage • Post curve warning sign • Reduce posted/regulated speeds • Reduce speed limit • Reduce speed limit • reduced speed advisory signing • reduced speed warning signs • Reduction of design speed and/or posted speed • Reflectors on barrier • Right-of-way • Signage • Signage/lower posted speed • signing • Signing • Signing • Signing, milled shoulder rumble strips, partial width paved shoulders • Signing, VMS messaging and advance warnings • signing; widening on curves (not common, but used)
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From page 158... ...
156 • Driver expectancy • illumination, signing, speed reduction • Improve lighting • lighting • Lighting • Lighting sag vertical curve • Lighting/lower posted speed • Marking no-passing zones • N/A • None • None. • Reduce speed limit • Reduce speed limit • Reduce speed limit • reduced speed warning signs, lighting • Reduction of design speed and/or posted speed • Right-of-way • sharper vertical curve • Signage • Signage for crest curves and lighting for sag curves • signing • Signing • Signing • Signing, lighting in some cases • Signing, VMS messaging and advance warnings • Speed reduction • Street lighting of substandard sag vertical curves.
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From page 159... ...
157 • Signing • Signing • Signing • Signing • Signing • Signing • signing or climbing lane • Signing, escape ramps, passing opportunities • Signing, VMS messaging, advance warnings, climbing lanes, passing lanes and truck escape ramps • Speed reduction • steep grade advisory signing • steeper grade • Truck climbing lane • warning signs • Warning signs, advisory speed signs Mitigation Measure Impact on Acceptance of Design Exception 18 More Likely 15 Equally Likely 1 Less Likely Stopping Sight Distance Most Common Mitigation Measure • Adjust horizontal/vertical curve alignments • Entrance/Intersecting Road relocation • Evaluation of features associated with the site. • Improve signage • Improve signing, advanced warning and reduce posted speeds • Lighting sag vertical curve • lighting, lower posted speed; signage • Lower posted speed/signage • Marking no-passing zones • none • none • not considered • Reduce Speed • Reduce speed limit • Reduce speed limit • Reduce speed limit • reduced speed advisory signing • Reduction of design speed and/or posted speed • Right-of-way • Safety • Signage advance warning • signing • Signing • Signing • Signing and reduced posted speeds • Signing and/or lighting • Signing, advisory signing • signing, illumination • SSD is rarely excepted but could be mitigated with speed reductions or signing • Use a low barrier when median barrier is a sight obstruction.
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From page 160... ...
158 Mitigation Measure Impact on Acceptance of Design Exception 16 More Likely 12 Equally Likely 1 Less Likely Cross Slope Most Common Mitigation Measure • Additional drainage features • Closely spaced drainage inlets or other drainage facilities • Consider lower posted speed (urban areas)
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From page 161... ...
159 • lower posted speed, improve skid resistance • None • None • None. • Pavement markings, rumble strips • Post curve warning sign • Reduce Speed • Reduce speed limit • Reduce speed limit • reduced speed advisory signing • reduced speed warning signs • reduced superelevation • Reduction of design speed and/or posted speed • Reflectors on barrier • Right-of-way • Roadside safety improvements • Safety • Signage • Signage • signing • Signing • Signing and reduced posted speeds • Speed reduction and advisory signing • Wearing surface friction, advisory signs Mitigation Measure Impact on Acceptance of Design Exception 13 More Likely 14 Equally Likely 3 Less Likely Vertical Clearance Most Common Mitigation Measure • Advance signing, truck restriction • Advance warning for motorists • Advance warning signs • Advanced warning signs • Advanced Warning Signs • Advisory signing • Another route with adequate clearance • Improve signage • Not used.
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From page 162... ...
160 • Signing • Signing • Signing • Signing • Signing • Signing, load height restrictions, and advance warnings • signing, public outreach, detours • Signing. • Truck restrictions • warning signs Mitigation Measure Impact on Acceptance of Design Exception 18 More Likely 13 Equally Likely 2 Less Likely Horizontal Clearance Most Common Mitigation Measure • barrier • Barrier • Barrier to shield object • Delineate objects • Delineation • delineation of roadside obstacles • Delineation, shielding • delineation, shielding, reduce pole conflicts with joint use requirements.
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From page 163... ...
161 Future 34. Are there any plans to reevaluate how your agency evaluates trade-offs in the design selection process in the next 6 to 12 months?
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162 • Planning to place more emphasis on risk and cost related to design exceptions. • Recently updated.
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From page 165... ...
163 • We are shifting to a Matrix type of organization at this time and part of the process is to look at more risk analysis on projects. Currently we have consultants perform risk analysis on projects over $100 million and are looking at doing a reduced risk analysis on projects above $20 million.
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From page 166... ...
NEED SPINE WIDTH TRANSPORTATION RESEARCH BOARD 2011 EXECUTIVE COMMITTEE* OFFICERS Chair: Neil J
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From page 167... ...
92+ pages; Perfect Bind with SPINE COPY = 14 pts Trade-Off Considerations in Highway Geometric Design NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM NCHRP SYNTHESIS 422 N CH R P SYN TH ESIS 422 Trade-Off Considerations in Highw ay Geom etric Design NEED SPINE WIDTH Job No. XXXX Pantone 202 C TRANSPORTATION RESEARCH BOARD 500 F ifth S treet, N .W .
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