Evaluation of Safety, Design, and Operation of Shared-Use Paths
FHWA-HRT-05-139
March 2006
FHWA Contact: Ann Do, 202-493-3319
PDF Version (234 KB)
The Pedestrian and Bicycle Safety Research Program focuses on identifying problem areas for pedestrians and bicycles, developing analysis tools that allow planners and engineers to better understand and target these problem areas, and evaluating countermeasures to reduce the number of crashes involving pedestrians and bicycles.
Introduction
This TechBrief is a summary of Evaluation of Safety, Design, and Operation of Shared-Use Paths: Final
Report, FHWA-HRT-05-137.
Shared-use paths are paved, off-street travelways that serve
bicyclists, pedestrians, and other nonmotorized modes
of travel, as shown in figure 1. The Federal Highway Administration (FHWA) has
developed a new method to estimate the level of service (LOS) on a shared-use
path, using a team of researchers led by the North Carolina State University
Department of Civil, Construction, and Environmental Engineering.
Figure 1. Hikers, bicyclists, and skaters often share the same pathways. |
Answering Key Questions
During the planning or design of every shared-use path, someone eventually asks, "How wide should this pathway be?" That question almost always raises even more questions: "What types of users can we
reasonably expect? When will we need to widen the path? Do we need to separate
different types of users from each other?" Before this project, these key
questions were difficult to answer. The American Association of State Highway
and Transportation Officials (AASHTO) Guide
for the Development of Bicycle Facilities (1999) provides general guidance
regarding path width (3.0 meters
(m) (10 feet (ft)), or 3.7 to 4.2 m (12 to 14 ft) with
substantial mixed use), but no specifics.(1) The Transportation
Research Board (TRB) Highway Capacity
Manual (2000) provides a method to calculate the LOS (A through F rating)
for a path; however, this method has several important limitations, such as
only including certain types of passing movements, assuming that path users
never impede each other, including only pedestrians and bicyclists, and using
fixed values for pedestrian and bicycle speeds.(2)
Objectives
The project's purpose was to develop a service model that
professionals could use to assist with the planning, design, and management of
shared-use paths and to answer the key questions posed above. In particular,
the project was to produce a tool that would overcome the limitations in the
current LOS procedure. The new service model would:
- Be calibrated and validated.
- Be based on U.S. data.
- Have LOS criteria based on user input for a typical mix of trip purposes.
- Include more modes than just pedestrians and bicycles.
- Include the ability to change key parameters, such as mean speeds.
- Account for delayed passing.
- Analyze the full range of existing and possible path widths.
- Be in a form ready for use by path designers.
The four major work items needed to achieve the project objectives were:
- Develop an additional theoretical framework.
- Collect information on path operations to increase the predictive ability of the framework, so that theoretical predictions match reasonably well with field observations.
- Collect path-user perception data to establish LOS criteria.
- Develop a new LOS estimation tool.
New Theory
To achieve these objectives, the project team had to develop
two important new aspects of the theory of traffic flow on shared-use paths.
First, the team had to develop improved methods to estimate the number of
meetings (opposite direction encounters) and passes (same direction encounters)
for a wide variety of path users. Second, the team had to find a way to
calculate the number of delayed passes (i.e., the number of times that a
bicyclist arrives behind a slower path user and is not able to pass because of
the lack of an adequate-sized gap in the lane to the left). Obviously, delayed
passes are undesirable for bicyclists, and they are critical because they are
so highly related to path width. Delayed passes were not included in the Highway Capacity Manual procedure.(2)
Coast-to-Coast Data Collection
To calibrate and validate the new service model and the LOS
procedure, the main variables that needed to be collected were meetings and
passes by path users. Other necessary data included the speeds of different
types of path users. Most of the data was collected by using a camera mounted
on the helmet of a test bicyclist. The data collection sites were some of the
busiest and best-known trails in the
United States, such as:
- Pinellas Trail near St. Petersburg, FL.
- South Bay Trail in Santa Monica, CA.
- Sammamish River Trail near Seattle, WA.
- Forest Park Trail in St. Louis, MO.
- Lakefront Trail in Chicago, IL.
- Dr. Paul Dudley White Bike Path near Boston, MA.
Overall,
the 15 data collection trails in 10 cities represented a wide range of
shared-use path conditions, including trail widths
ranging from 2.4 to 6.1 m (8 to 20 ft).
The researchers made nearly 800 data collection rides of 0.8 kilometer (0.5 mile) each on the 15
trails. Most rides were on weekends in good weather. Some of the most important
findings were:
- Five travel modes were used by almost all of the users of the studied trails. Average mode splits
were 56 percent adult bicyclists, 3 percent child bicyclists, 18 percent
pedestrians, 13 percent runners, and 10 percent inline skaters.
- The average trail had 430 users per hour.
- The average bicycle speed was 20.6 kilometers per hour (12.8 miles per hour).
Overall, the field data matched the theoretical
predictions very well, as figure 2 shows for the case of the number of
meetings.
Figure 2. The number of meetings on a path segment as observed in the field and as predicted by the new model. |
Asking the Users
The research team surveyed 105 trail users (primarily
bicyclists) to determine what factors they found to be significant in their
evaluation of comfort and freedom to maneuver on shared-use paths. The
respondents viewed and rated 60-second video clips of shared path operations;
these clips were filmed by the researchers using the helmet camera during field
data collection. The researchers tested a wide variety of factors to determine
their overall influence on survey responses. The primary factors found to
affect trail users' perceived LOS included:
- Path width.
- Active passes by the bicyclists of slower path users.
- Meetings.
- The presence of a centerline.
The researchers added an adjustment for the number of
delayed passes and produced the LOS equation and scale shown in figure 3.
Figure 3. LOS equation. |
A New Procedure
Combining the new theory, the field data, and the user survey, the researchers produced an improved LOS estimation procedure for shared-use paths. Table 1 shows a few examples of service predictions. However, readers must use this table cautiously because it is based on many assumptions, including assumptions about user speed and mode splits. The Final Report and Shared-Use Path Level of Service Calculator: A User's Guide, FHWA-HRT-05-138, contains many more examples like this.(3,4)
Table 1. Example of LOS predictions.
Trail users per hour in each direction |
Trail width (feet) |
8 |
12 |
16 |
20 |
25 |
B |
B |
A |
A |
50 |
D |
B |
A |
A |
75 |
D |
B |
B |
A |
100 |
D |
B |
B |
A |
150 |
E |
C |
B |
B |
200 |
F |
D |
C |
B |
250 |
F |
D |
C |
C |
300 |
F |
E |
D |
C |
400 |
F |
F |
E |
E |
500 |
F |
F |
F |
F |
1 foot=0.305 meters
Users of the service estimation procedure need to remember that its scope is limited to uninterrupted segments of paved, off-street paths, from 2.4 to 6.1 m (8 to 20 ft) wide, and that the LOS is presented from the bicyclist's viewpoint only.
SUPLOS Calculator
The Shared-Use Path Level of Service (SUPLOS) calculator
is a spreadsheet developed during this research that quickly and accurately
executes the new LOS estimation procedure. Professionals can use the calculator
to guide planning, design, and/or management decisions regarding path width and
user mix on shared-use paths. Input is simple, requiring only four variables:
- One-way path users per hour.
- Mode split.
- Path width.
- Presence or absence of a centerline.
Analysts may elect to use the default mode split provided in
the calculator if reliable mode split data are not available.
The SUPLOS calculator example depicted in table 2 shows how
easy it is to use the tool. The User's Guide provides detailed instructions for
the calculator, offers case studies in which it is employed, and describes a
variety of applications for which the calculator can be used.(4)
Table 2. Sample SUPLOS calculator spreadsheet.
Segment
Name |
Path Width |
Centerline |
Volume (users per hour in 1 direction) and Mode Split |
Trail Level of Service |
| Closest
0.5 ft. |
0=No Centerline |
Volume |
Mode Split (%)* |
|
Name | Width
(ft.) |
1=Centerline |
One-Way
(per hour) |
Adult Bicyclists |
Pedestrians |
Runners |
Inline Skaters |
Child
Bicyclists |
All Modes |
LOS Score |
LOS Grade |
Example
Trail | 11.0 |
1 |
160.0 |
55.0% |
20.0% |
10.0% |
10.0% |
5.0% |
100.0% |
3.12 |
C |
For More Information
Ann Do
Federal Highway Administration
202-493-3319
ann.do@fhwa.dot.gov
References
- Guide for the Development of Bicycle Facilities, American Association of State Highway and Transportation Officials, Washington, DC, 1999.
- Highway Capacity Manual, Transportation Research Board, Washington, DC, 2000.
- Hummer, J.E., N.M. Rouphail, J.S. Green, R.G. Hughes, S.J. Fain, J.L. Toole, R.S. Patten and R.J. Schneider. Evaluation of Safety, Design, and Operation of Shared-Use Paths: Final Report, FHWA-HRT-05-137, Federal Highway Administration, McLean, VA, 2005.
- Patten, R.S., R.J. Schneider, J.L. Toole, N.M. Rouphail, J.E. Hummer, J.S. Green, R.G. Hughes. Shared-Use Path Level of Service Calculator: A User's Guide, FHWA-HRT-05-138, Federal Highway Administration, McLean, VA, 2005.
Other Sources
Rouphail, N., J. Hummer, J. Milazzo II and D.
Allen. Capacity Analysis of
Pedestrian and Bicycle Facilities: Recommended Procedures for the Bicycles
Chapter of the Highway Capacity Manual, FHWA-RD-98-108, Federal
Highway Administration, McLean,
VA, 2000.
Harkey, D., D. Reinfurt, A. Sorton,
M. Knuiman, and J. Richard Stewart. The Bicycle Compatibility Index: A Level of
Service Concept, Implementation Manual, FHWA-RD-98-095, Federal
Highway Administration, McLean,
VA, 1998.
Research—This
work was performed by the North Carolina State University Department of Civil,
Construction and Environmental Engineering, the University of North Carolina
Highway Safety Research Center, and Toole Design Group.
Distribution—This
TechBrief is being distributed according to a standard distribution. Direct
distribution is being made to the Resource
Center and Divisions.
Availability—The publication from which this TechBrief was developed, Evaluation of Safety, Design, and Operation of Shared-Use Paths: Final Report, FHWA-HRT-05-137, is available from the National Technical
Information Service, 5285 Port Royal Road, Springfield, VA, 22161 (www.ntis.gov).
A limited number of copies are available from the FHWA Research and Technology
Product Distribution
Center, HRTS-03, FHWA, 9701
Philadelphia Court, Unit Q, Lanham,
MD, 20706.
Key Words—Path, trail, bicycle, shared-use, level of service, width,
pedestrian, inline skater.
Notice—This
TechBrief is disseminated under the sponsorship of the U.S. Department of
Transportation in the interest of information exchange. The TechBrief does not
establish policies or regulations, nor does it imply FHWA endorsement of the
conclusions or recommendations. The U.S. Government assumes no liability for
the contents or their use.
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