Table
of Contents | List of Figures |
List of Tables |
Abbreviations
& Acronyms
| How
to Use this Handbook
Recommendations:
I.Intersections (At-Grade)
| II. Interchanges
(Grade Separation)
III. Roadway Curvature and Passing Zones | IV.
Construction/Work Zones | V.
Highway-Rail Grade Crossings (Passive)
Rationale and Supporting Evidence: I.
Intersections (At-Grade) | II.
Interchanges (Grade Separation) | III.
Roadway Curvature and Passing Zones | IV.
Construction/Work Zones | V.
Highway-Rail Grade Crossings (Passive)
Glossary | References
| Index
HOW TO USE THIS HANDBOOK
RELATING RECOMMENDATIONS TO STANDARD DESIGN GUIDES
Codes placed outside and to the left of each recommendation in this Handbook
indicate its relationship to the design guides most frequently referenced by
practitioners, as determined by the Handbook authors. An example is shown below.
Recommendations by Design Element A. Design Element: Intersecting Angle (Skew)
|
Relationship codes 1 through 4, plus a fifth code (IEC), are defined as follows:
1 | Handbook recommendation selects the most conservative design value among present options in the standard manual/guideline. (Example: Using a larger sign size identified as an "option" in the MUTCD). |
2 | Handbook recommendation indicates the preferred design value where a discrepancy exists between current standards/guidelines. (Example: Limit skew to 75 as per ITE instead of 60 as per AASHTO). |
3 | Handbook recommendation extends a current practice to a new application or operation. (Example: Use of fluorescent sheeting on wrong-way control signing, for increased conspicuity). |
4 | Handbook recommendation advances a specific design value where only general guidance now exists, or provides more detailed or more stringent design criteria than are currently specified. (Example: Assume 0.4 m of visibility per mm [33 ft per inch] of letter height on highway signing, not 0.6 m/mm [50 ft/in] as in MUTCD 1988, or even 0.5 m/mm [40 ft/in] as proposed for MUTCD 2000). |
IEC | Handbook recommendation is permissible at this time only in accordance with the provisions of MUTCD section 1A.10, Interpretations, Experimentations, and Changes. These recommendations represent advances in technology which research indicates will result in improved safety and efficiency of operations. |
The standard design guides referenced by the relationship codes in the example above and throughout the Handbook are listed below. The most current published edition of each guide was consulted in the preparation of the Handbook, with the exceptions as noted.
AASHTO | A Policy on Geometric Design of Highways and Streets. American Association of State Highway and Transportation Officials, 1994. |
HCM | Highway Capacity Manual. Transportation Research Board, 1999.
(Special Report 209) |
ICG | Intersection Channelization Design Guide. National Cooperative Highway Research Program, 1985. (Report No. 279) |
ITE | Traffic Engineering Handbook. Institute of Transportation Engineers, 1999. |
MUTCD | Manual on Uniform Traffic Control Devices for Streets and Highways. Federal Highway Administration, 2000. |
RLH | Roadway
Lighting Handbook. Federal Highway Administration, 1978. Implementation
Package 78-15. (Reprinted April 1984) [NOTE: Although an Addendum to Chapter Six of the Roadway Lighting Handbook was produced in 1983, the recommendations pertaining to the RLH primarily reference material found in the chapters produced in the 1978 version.] |
RND | Roundabouts: An Informational Guide. Federal Highway Administration, 2000. |
RRX | Railroad-Highway Grade Crossing Handbook. Federal Highway Administration, 1986. |
INTERPRETING HANDBOOK GRAPHICS
The included figures and drawings are for illustrative purposes only, to clarify the meaning of a recommendation or to show what design was employed in a research study referenced in the Rationale and Supporting Evidence section. It is important to note that the fonts and arrow graphics used in this Handbook are not always consistent with the MUTCD-approved fonts and arrows. When employing recommendations included in this Handbook, only MUTCD-approved fonts and arrow graphics should be used.
USING THE TIME-SPEED-DISTANCE TABLE
A number of recommendations presented in the Handbook identify the placement of a device or treatment in terms of the preview time that should be provided to the driver for its application. These values are typically expressed in seconds, such that the recommended placement of the device or treatment depends upon the speed at which traffic is moving. To facilitate application of Handbook recommendations of this nature, a look-up table on the next page provides the advance placement distance needed to achieve a desired preview time at a particular operating speed.
Advance
Placement Distances Required to Achieve Desired Preview Times at Designated
Operating Speeds
Preview
Time (seconds) |
Operating Speed | ||||||||||
48
km/h (30 mi/h) |
56
km/h (35 mi/h) |
64 km/h (40 mi/h) | 72
km/h (45 mi/h) |
80
km/h (50 mi/h) |
88
km/h (55 mi/h) |
97
km/h (60 mi/h) |
105
km/h (65 mi/h) |
113
km/h (70 mi/h) |
121
km/h (75 mi/h) |
129
km/h (80 mi/h) |
|
2.5 | 34
m (110 ft) |
39 m (128 ft) | 45 m (147 ft) | 50
m (165 ft) |
56
m (183 ft) |
62
m (202 ft) |
67
m (220 ft) |
73
m (238 ft) |
78
m (257 ft) |
84
m (275 ft) |
89
m (293 ft) |
3.0 | 40
m (132 ft) |
47
m (154 ft) |
54
m (176 ft) |
60
m (198 ft) |
67
m (220 ft) |
74 m (242 ft) | 81 m (264 ft) | 87
m (286 ft) |
94
m (308 ft) |
101
m (330 ft) |
107
m (352 ft) |
3.5 | 47
m (154 ft) |
55 m (180 ft) | 63
m (205 ft) |
70
m (231 ft) |
78
m (257 ft) |
86
m (282 ft) |
94
m (308 ft) |
102
m (334 ft) |
110
m (359 ft) |
117
m (385 ft) |
125
m (411 ft) |
4.0 | 54
m (176 ft) |
63
m (205 ft) |
72 m (235 ft) | 81
m (264 ft) |
89 m (293 ft) | 98
m (323 ft) |
107
m (352 ft) |
116
m (381 ft) |
125
m (411 ft) |
134
m (440 ft) |
143
m (469 ft) |
4.5 | 60
m (198 ft) |
70
m (231 ft) |
81
m (264 ft) |
91
m (297 ft) |
101
m (330 ft) |
111
m (363 ft) |
121
m (396 ft) |
131
m (429 ft) |
141
m (462 ft) |
151
m (495 ft) |
161
m (528 ft) |
5.0 | 67
m (220 ft) |
78 m (257 ft) | 89 m (293 ft) | 101
m (330 ft) |
112 m (367 ft) | 123
m (403 ft) |
134
m (440 ft) |
145
m (477 ft) |
157 m (513 ft) | 168
m (550 ft) |
179
m (587 ft) |
5.5 | 74
m (242 ft) |
86 m (282 ft) | 98
m (323 ft) |
111
m (363 ft) |
123
m (403 ft) |
135
m (444 ft) |
148
m (484 ft) |
160
m (524 ft) |
172 m (565 ft) | 185
m (605 ft) |
197
m (645 ft) |
6.0 | 81
m (264 ft) |
94
m (308 ft) |
107 m (352 ft) | 121
m (396 ft) |
134 m (440 ft) | 148
m (484 ft) |
161
m (528 ft) |
174
m (572 ft) |
188
m (616 ft) |
201
m (660 ft) |
215
m (704 ft) |
6.5 | 87
m (286 ft) |
102 m (334 ft) | 116 m (381 ft) | 131
m (429 ft) |
145
m (477 ft) |
160
m (524 ft) |
174 m (572 ft) | 189
m (620 ft) |
204
m (667 ft) |
218
m (715 ft) |
233
m (763 ft) |
7.0 | 94
m (308 ft) |
110
m (359 ft) |
125 m (411 ft) | 141
m (462 ft) |
157
m (513 ft) |
172
m (565 ft) |
188
m (616 ft) |
204
m (667 ft) |
219
m (719 ft) |
235
m (770 ft) |
250
m (822 ft) |
7.5 | 101
m (330 ft) |
117
m (385 ft) |
134
m (440 ft) |
151
m (495 ft) |
168
m (550 ft) |
185 m (605 ft) | 201 m (660 ft) | 218
m (715 ft) |
235
m (770 ft) |
252
m (825 ft) |
268
m (880 ft) |
8.0 | 107
m (352 ft) |
125
m (411 ft) |
143 m (469 ft) | 161
m (528 ft) |
179 m (587 ft) | 197
m (645 ft) |
215
m (704 ft) |
233
m (763 ft) |
250
m (822 ft) |
268
m (880 ft) |
286
m (939 ft) |
KNOWING WHEN TO IMPLEMENT THESE RECOMMENDATIONS
Implementation of the recommendations in this Handbook is expected to provide remedies for design deficiencies that disproportionately penalize older road users due to changes in functional ability experienced with normal aging. These may be most urgently needed where a crash problem with older drivers or pedestrians has already been demonstrated; however, the greater benefit arguably lies in designing safer new roads and identifying and modifying problems with existing roads before statistics reveal a crash problem. Not only does this practice minimize the risk and severity of crashes, it minimizes the need for remedial works after construction, thus reducing the whole-life cost of projects. This is the central premise of the road safety audit process supported by FHWA (1997) and ITE (1995), and it holds the key for applying the Handbook's recommendations as well.
The engineering enhancements described in this document should benefit all road users, not just older persons. However, if higher construction costs, the need for additional right-of-way, or other factors are present, special justification may be required for implementation of Handbookpractices. This section was developed to support engineering judgment in this regard. It suggests a three-step procedure using checklist responses plus brief written comments, as explained below. A separate Implementation Worksheet for meeting the requirements of each step is also provided. It is assumed that DOT's have in place processes that define when a crash pattern or a safety problem is evident; this Handbook does not address this level of analysis. Furthermore, it is recognized that States may already follow processes that make the approach described in this section unnecessary. FHWA has no desire to interfere with any procedures used by States that take the same information into account and accomplish the same ends as the three-step procedure below.
Step 1: Problem Identification [see worksheet on page 6]
During the planning stage for each project involving new construction or reconstruction of an existing facility, practitioners are asked to determine whether a problem with the safe use of the facility by older drivers and pedestrians currently exists or may reasonably be expected based on current and projected use patterns. Using the first worksheet that follows this discussion, problem identification can be accomplished by checking YES or NO to the following four questions:
Q1. "Is there a demonstrated crash problem with older drivers or pedestrians?"
Q2. "Has any aspect of design or operations at the project location been associated with complaints to local, municipal, or county-level officials from older road users or are you aware of a potential safety problem at this location, either through personal observation or agency documentation, applying your own engineering judgment?"
Q3. "Is this project located on a direct link to a travel origin or destination for which, in the judgment of local planning/zoning authorities or other local officials, older persons constitute a significant proportion of current users?"
Q4. "Is the project located in a census tract or zip code designation that has experienced an increase in the proportion of (non-institutionalized) residents age 65 and older, for the most recent period in which the population was sampled?"
To answer these questions, practitioners will need to obtain reliable crash data from the appropriate division or bureau of their departments of transportation. At least the three most recent years for which data are available should be examined, and the data should be sorted by age, at a minimum. Sources of information outside of the State DOT also may be required to answer the problem identification questions. Potential sources include, but are not limited to:
Step 2: Identification of Candidate Handbook Applications [see worksheet on page 7]
For each project where a practitioner
has answered YES to one or more of the problem identification questions in Step
1, the next step is to identify every design element at the to-be-constructed
facility for which a recommendation is included in the Handbook. These recommendations
should be listed. Then, for each one, the engineer should indicate whether the
recommended practice differs from standard State or local practices, and if
yes, what additional benefits are expected to result from implementing the applicable
Handbook recommendation(s). One possible example of how such worksheet entries
could be made is shown below.
Design Elements Addressed by Handbook Recommendations | Applicable Handbook Recomm. | Differs From Existing State or Local Practice? | If YES... | ||
NO | YES | Explain Difference | Identify Expected Benefits | ||
IA. Intersection Angle (Skew) | IA(3) | According to MUTCD warrants, there is "adequate" sight distance and fewer than 3 RTOR crashes annually on approach. | Should reduce the difficulty for older drivers to check for approaching traffic, and also reduce aggressive behavior of following drivers who don't accept an older driver's decision not to turn on red. | ||
IJ. Street-Name Signing | IJ(1) |
Step 3: Implementation Decision [see worksheet on page 8]
To begin Step 3, each Handbook recommendation identified as a candidate for imple-mentation in Step 2 should be properly referenced [e.g., I.E.4(4a)]. Next, any factors relating to increased costs (for an enhanced treatment), added approvals that may be needed, or any other special considerations that impact implementation may be noted in separate columns on the worksheet. The final step is then to proceed to an implementation decision. This is recorded as a judgment by the engineer as to whether implementation of the candidate countermeasure is recommended. The engineer's judgment is indicated by a check in the space next to YES or NO in the last column on the worksheet, accompanied by his/her initials for verification. Additional comments should be entered as deemed appropriate.
STEP 1: Problem Identification/Project Review Worksheet for Highway Design Handbook for Older
Drivers and Pedestrians
Project Title/ID: ____________________________________________________________________
Person Completing Worksheet: ___________________________ Date: ____________
NO ____ YES ____ |
Q1. "Is there a demonstrated crash problem with older drivers or pedestrians?"
Source(s): _________________________________________________ |
Date of Contact: ______________ |
NO ____ YES ____ |
Q2. "Has any aspect of design or operations at the project location been associated with complaints to local, municipal, or county-level officials from older road users or are you aware of a potential safety problem at this location, either through personal observation or agency documentation, applying your own engineering judgment?"
Source(s): _________________________________________________ |
Date of Contact: ______________ |
NO ____ YES ____ |
Q3. "Is this project located on a direct link to a travel origin or destination for which, in the judgment of local planning/zoning authorities or other local officials, older persons constitute a significant proportion of current users?"
Source(s): _________________________________________________ |
Date of Contact: ______________ |
NO ____ YES ____ |
Q4. "Is the project located in a census tract or zip code designation that has experienced an increase in the proportion of (non-institutionalized) residents age 65 and older, for the most recent period in which the population was sampled?
Source(s): _________________________________________________ |
Date of Contact: ______________ |
Implementation Worksheet for Highway Design Handbook for Older Drivers and Pedestrians
Project Title/ID: _______________________________________________________________
Person Completing Worksheet: _________________________________ Date: ____________
Step 2: Identification of Candidate Handbook Applications
Identify design elements for which a recommendation exists in the Handbook and theapplicable recommendations. Then, (a) describe differences between the recommendation and standard practice, and (b) list benefits expected to result from implementing the Handbook.
Design Elements Addressed by Handbook Recommendations | Applicable Handbook Recomm. | Differs From Existing State or Local Practice? | If YES... | ||
NO | YES | Explain Difference | Identify Expected Benefits | ||
|
|||||
|
|||||
|
Implementation Worksheet for Highway Design Handbook for Older Drivers and Pedestrians
Project Title/ID: ________________________________________________________________________
Person Completing Worksheet: _________________________________________Date: ____________________
Step 3: Implementation Decision
List each recommendation identified as being a candidate for implementation. Document whether additional approval is needed, and whether increased costs or other special considerations may impact implementation. Based on these considerations, then decide whether or not implementation can be recommended. Check YES or NO, and add your initials to record your judgment. Add supplemental comments as deemed appropriate.
Candidate Handbook Recommendation | Implementation Considerations | Implementation Recommended? | ||
Added Costs? | Added Approvals? | Other | ||
|
|
NO _____ Initials
_______
YES _____ Comments: | ||
NO _____ Initials
_______
YES _____ Comments: |
Table
of Contents | List of Figures |
List of Tables |
Abbreviations
& Acronyms
| How
to Use this Handbook
Recommendations:
I.Intersections (At-Grade)
| II. Interchanges
(Grade Separation)
| III.
Roadway Curvature and Passing Zones
IV.
Construction/Work Zones | V.
Highway-Rail Grade Crossings (Passive)
Rationale and Supporting Evidence: I.
Intersections (At-Grade) | II.
Interchanges (Grade Separation) | III.
Roadway Curvature and Passing Zones | IV.
Construction/Work Zones | V.
Highway-Rail Grade Crossings (Passive)
Glossary | References
| Index
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