February 2021

© Toole Design

TRAFFIC ANALYSIS AND 

INTERSECTION 

CONSIDERATIONS TO INFORM 

BIKEWAY SELECTION
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

i

TECHNICAL DOCUMENTATION PAGE

1. AGENCY USE ONLY (Leave Blank) 2. REPORT DATE

February 2021

3. REPORT TYPE AND DATES COVERED

Final Report

4. TITLE AND SUBTITLE

Traffic Analysis and Intersection Considerations to Inform 

Bikeway Selection

5a. FUNDING NUMBERS

NA

6. AUTHORS

Mosier, Barbara; Schultheiss, Bill; Goodman, Dan; Draper, Jared; Blackburn, 

Lauren

5b. CONTRACT NUMBER

DTFH61-16-D-00005

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

VHB, 940 Main Campus Drive, Suite 500

Raleigh, NC 27606

Toole Design Group, 8484 Georgia Avenue, Suite 800 

Silver Spring, MD 20910

8. PERFORMING ORGANIZATION REPORT

NUMBER

NA

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

Tamara Redmon

Project Manager, Office of Safety

Federal Highway Administration

1200 New Jersey Avenue SE

Washington DC 20590

10. SPONSORING/MONITORING AGENCY

REPORT NUMBER

FHWA-SA-21-010

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT

This document is available to the public on the FHWA website at:

https://safety.fhwa.dot.gov/ped_bike

12b. DISTRIBUTION CODE

NA

13. ABSTRACT

This resource supplements the Federal Highway Administration’s (FHWA) Bikeway Selection Guide and is intended to inform 

trade-off decisions associated with bikeway selection at intersections. It discusses common performance metrics, spatial 

needs of bikeways at intersections, safety and equity focused design principles, and operational traffic analysis trade-offs and 

assumptions.

14. SUBJECT TERMS

Bike, bicycle, bikeway, multimodal, networks, active transportation, 

low stress networks, bikeway selection, performance metrics, traffic, 

intersections

15. NUMBER OF PAGES

18

16. PRICE CODE

NA

17. SECURITY CLASSIFICATION 

OF REPORT

Unclassified

18. SECURITY 

CLASSIFICATION 

OF THIS PAGE

Unclassified

19. SECURITY 

CLASSIFICATION 

OF ABSTRACT

Unclassified

20. LIMITATION OF ABSTRACT

Unlimited
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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NOTICE

This document is disseminated under the sponsorship of the U.S. Department of Transportation in 

the interest of information exchange. The U.S. Government assumes no liability for the use of the 

information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ 

names appear in this report only because they are considered essential to the objective of this 

document.

The contents of this report reflect the views of the authors, who are responsible for the facts and 

accuracy of the data presented herein. The contents do not necessarily reflect the official policy of 

the U.S. Department of Transportation. This report does not constitute a standard, specification, 

or regulation.

Images in the report are intended to serve as examples of the range of real-world existing 

conditions; they are not limited to best practices or approved designs or behaviors and, in some 

cases, may reflect conditions that are not recommended.

Publication Number: FHWA-SA-21-010

CONTENTS

Introduction................................................................................................................................................ 1

Performance Metrics ................................................................................................................................... 2

Spatial Needs By Bikeway Intersection Type ..................................................................................................... 5

Safety and Equity Focused Design Principles ................................................................................................... 5

Traffic Analysis Assumptions and Analysis Tips ............................................................................................... 9

Discussion Prompts ................................................................................................................................... 12

Conclusion ............................................................................................................................................... 13
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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Introduction

Decisions made about the design and operation of street intersections have historically played 

a central role in the bikeway selection process because these decisions have often been based 

primarily on favoring motor vehicle traffic. Selecting a bikeway facility that increases safety and 

aligns with community goals can be challenging when agencies are attempting to reallocate 

existing space to and through intersections for bicyclists without impacting motorists and other 

existing intersection users. This resource supplements the Federal Highway Administration’s 

(FHWA) Bikeway Selection Guide and is intended to inform mobility, safety, equity, and policy 

trade-off decisions associated with bikeway selection at intersections. 

Figure 1: Crossing Locations Relative to Intersection Functional Area. 

Source: FHWA

This document also supplements other resources including 

those from FHWA, American Association of State Highway and 

Transportation Officials (AASHTO), the National Association 

of City Transportation Officials (NACTO), and the Institute of 

Transportation Engineers (ITE), which provide detailed design 

guidance not provided in this document. Design considerations 

will be noted with references provided to these resources as 

appropriate.

The consideration of traffic impacts is central to the bikeway 

selection decision because in many locations existing 

property lines; existing curbs, drainage, and utilities; and in 

some communities, buildings, constrain what can be done 

within the right-of-way (ROW). Expanding right-of-way can 

be especially costly where it is necessary to modify these 

typical features. Designers need to ensure retrofits preserve or 

enhance pedestrian accessibility. They should also be aware 

that changes on one intersection leg can affect the width of 
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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the entire intersection, as well as the width approaching the 

intersection—described as the intersection’s functional area 

(see Figure 1). The functional area of an intersection as defined 

in the AASHTO “A Policy on the Geometric Design of Highways 

and Streets” extends both upstream and downstream from the 

physical intersection area and includes any auxiliary lanes and 

their associated channelization where vehicles routinely queue 

at the intersection. 

This document includes the following sections:

• Performance Metrics should be used to guide decision 

making and inform trade-off evaluation. 

• Spatial Needs by Bikeway Intersection Type are a building 

block for considering bikeway safety and comfort benefits.

• Safety and Equity Focused Design Principles set the 

foundation for the planning and design of a transportation 

system that is safe and equitable for all users. This section 

builds on the intersection performance characteristics by 

bikeway type that are highlighted in the Bikeway Selection 

Guide (pp. 16-17) based on Sustainable Safety principals.

• Traffic Analysis Assumptions and Analysis Tips are provided 

to establish a basic understanding of standard traffic analyses 

approaches and their associated inputs. A general overview 

of this information provides common ground for future tradeoff conversations when considering a project that changes 

the existing roadway and intersection operation schemes.

Performance Metrics 

To assess intersection and bikeway design alternatives, 

performance metrics need to be established. The most 

common performance metric used is vehicular Level of Service 

(LOS), which is derived from either vehicular delay or the volume 

to capacity ratio (v/c) based on Transportation Research Board 

(TRB) Highway Capacity Manual (HCM) methodologies. In 

the past, these two measures have often been the primary 

or only metrics considered in the analysis of intersections. 

However, the HCM contains guidance discouraging a narrow 

focused approach, stating that, “(n)either LOS nor any other 

single performance measure tells the full story of roadway 

performance.” 

When vehicular LOS is relied on in isolation, potential negative 

impacts on vehicular operations are given undue weight and are 

not balanced against potential impacts on other roadway users, 

for example relating to accessibility and benefits associated 

with the installation of a bikeway. To minimize impacts on 

motorists as measured through LOS, a common strategy has 

been to downgrade the quality of a bikeway to a lesser facility 

or to terminate a bikeway through an intersection to maintain or 

provide additional vehicular capacity to meet an arbitrary LOS 

criterion. When this happens project and community goals such 

as increased bicyclist safety, increased bicycle mode share, and 

bicycle network connectivity are compromised.

© Toole Design
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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At the outset of a project process that will include intersection 

design alternatives analysis, it is vital that performance measures 

are established to reflect the goals of the project and the 

community, as well as adopted policies. Motor vehicle level 

of service cannot serve this purpose alone. There are many 

performance metrics relevant to community goals and agency 

policies that are generally applied at the facility or small-area level 

such as bicycle network connectivity, mode shift targets, livability, 

and climate change impact. The NACTO Urban Street Design 

Guide and the FHWA Guidebook for Developing Pedestrian 

and Bicycle Performance Measures are helpful resources to 

review when establishing performance metrics. Accessibility 

for pedestrians with disabilities and pedestrian safety in general 

should always be included in performance metrics discussions. 

The following are common performance metrics relevant to 

intersection analysis that should also be considered during 

bikeway selection and in general intersection design: 

Safety

Safety should be a priority focus of the design selection 

process. The chosen performance metrics can include an 

assessment of the safety of the design alternatives compared 

to the baseline condition for bicyclists, pedestrians and other 

roadway users. In contexts where extensive analytical resources 

are available, historical crash data, crash modification factors, 

and safety performance functions can be used to quantify the 

safety impact of various design choices using methods such as 

those outlined in the AASHTO Highway Safety Manual (HSM). 

However, as discussed in NCHRP 926 “...this method should be 

used with caution, as there are factors... that may increase or 

decrease the expected number of bicycle crashes that are not 

considered by the HSM method. Future updates to the HSM 

are expected to improve methods for estimating the number 

of bicycle and pedestrian crashes1

. The Pedestrian and Bicycle 

Intersection Safety Indices developed by the Pedestrian and 

Bicycle Information Center (PBIC) may be additional metrics to 

consider to conduct a quantitative safety analysis. In contexts 

where a detailed quantitative level of analysis is not feasible, 

safety can be more qualitatively assessed based on the 

Sustainable Safety Principals outlined in the Bikeway Selection 

Guide and discussed below. 

1 Highway Research Program; Transportation Research Board; National 

Academies of Sciences, Engineering, and Medicine National Academies 

of Sciences, Engineering, and Medicine 2020. Guidance to Improve 

Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The 

National Academies Press. https://www.nap.edu/catalog/25808/

guidance-to-improve-pedestrian-and-bicyclist-safety-at-intersections, 

pgs 39-40

For additional information on safety related metrics, consult the 

following resources: 

• AASHTO Highway Safety Manual 

• Crash Modification Clearinghouse 

(http://www.cmfclearinghouse.org/)

• NCHRP 926 - Guidance to Improve Pedestrian and Bicyclist 

Safety at Intersections (2020)

• NCHRP 948 - Guide for Pedestrian and Bicycle Safety at 

Alternative Intersections and Interchanges (Pending)

• Pedestrian and Bicyclist Intersection Safety Indices: 

User Guide (2007) https://www.fhwa.dot.gov/publications/

research/safety/pedbike/06130/06130.pdf

Accessibility for Pedestrians 

with Disabilities

Projects accommodating pedestrian/bicycle traffic need to 

consider accessibility for all individuals, including persons with 

disabilities, under Section 504 of the Rehabilitation Act of 1973 

(Section 504) (29 U.S.C. 794) and Title II of the Americans with 

Disabilities Act of 1990 (ADA) (42 U.S.C. 12131-12164), along 

with USDOT’s Section 504 regulations at 49 CFR Part 27 and the 

US Department of Justice’s (USDOJ) ADA Title II regulations at 

28 CFR Part 35.

The ADA requires that a public entity’s newly constructed 

facilities be made accessible to and usable by individuals with 

disabilities to the extent that it is not structurally impracticable 

to do so. See 28 CFR 35.151(a). The ADA also requires that, 

when an existing facility is altered, the altered facility be made 

accessible to and usable by individuals with disabilities to the 

maximum extent feasible. See 28 CFR 35.151(b). Determination 

of whether a given design is accessible per ADA, or whether it 

© Toole Design
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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improves existing accessibility for pedestrians in general as 

well as those with disabilities should be included as a primary 

screening metric. Separated bikeways and shared use paths will 

require pedestrian accommodation.

Pedestrian and Bike 

Quality of Service Metrics

There are several measures that have been developed to reflect 

the level of stress or comfort experienced by a pedestrian or 

bicyclist using a facility. These measures include Level of Traffic 

Stress2

 (LTS) or Bicycle and Pedestrian Environmental Quality 

Indices3

. Additional metrics such as Bicycle and Pedestrian Level 

of Service (BLOS and PLOS) combine user comfort, capacity, 

and street characteristics and are included in the HCM 2010 

Multi-Modal Level of Service (MMLOS) approach. Similar metrics 

developed by local jurisdictions may also be relevant and follow 

similar procedures. Each of these measures has some strengths 

and weaknesses which should be understood before use. For 

example, BLOS has been statistically validated, but the separated 

bike lane facility type was not included in the original analysis. 

LTS can be used to provide a comparison between all bikeway 

types, but was developed based on expert review.

For additional information on various Quality of Service metrics, 

consult the following resources: 

• Highway Capacity Manual, 2010

• Mineta Transportation Institute: Report 11-19 – Low-Street 

Bicycling and Network Connectivity2

• FHWA Guidebook for Developing Pedestrian and Bicycle 

Performance Measures

Traffic Analysis

While not suitable as a sole measure of intersection operations 

because it only assesses motorists delay and capacity, this 

metric can be illustrative for fine-tuning intersection design 

choices such as determining lane use allocation where 

right-of-way is available for more than one vehicular approach 

lane, testing phasing choices, or proposed signal timing splits. 

It is also helpful in revealing locations where excess capacity 

already exists, indicating a road diet or right-of-way reallocation 

may have limited impacts to motorists. Care should be taken 

when considering LOS impacts that vehicular impacts at a 

single intersection do not unduly influence design choices 

for an entire corridor, or for all modes. Vehicular delay can be 

2 Mekuria, M.C., P.G. Furth, and H. Nixon. Low-Stress Bicycling and 

Network Connectivity. MTI Report 11-19. Mineta Transportation 

Institute, San Jose State University, San Jose, CA, 2012. 

3 https://trid.trb.org/view/1326355

calculated using either the deterministic methodologies in the 

HCM, or by using microsimulation modeling as appropriate. 

Pedestrian and bicyclist delay should be calculated for 

comparison and to ensure modal balance is considered at 

intersections. For example, a common strategy to improve 

the LOS results in a traffic model is to eliminate a pedestrian 

crossing, requiring a pedestrian in some instances to make 

3 separate road crossings to cross a street, which can 

significantly increase their delay and exposure to conflicts with 

motorists. For guidance on the best approach for a given facility, 

consider the FHWA Traffic Analysis Toolbox4

 or relevant local 

guidance such as Virginia DOT’s Traffic Operations and Safety 

Analysis Manual5

 or Oregon DOT’s Analysis Procedures Manual6

Travel Time

Travel time is similar to vehicular delay in that reduced vehicle 

capacity will be reflected in an impact on travel time; however, 

travel time provides a wider view of impacts across a corridor. 

As outlined in the FHWA Guidebook for Developing Pedestrian 

and Bicycle Performance Measures, “The traditional focus on 

intersection vehicle delay as a performance measure tends 

to exaggerate the severity of congestion. For example, an 

intersection with average vehicle delay greater than 80 seconds 

is said to have LOS “F” and is 150% more delay than a driver might 

expect at a LOS “C” intersection. But that intersection likely only 

represents one point along a trip. Using a typical vehicle trip, that 

same increase in delay might represent a difference of 45 seconds 

in a 10-minute trip. Framed in this context, decision makers and 

community members might think differently about alternatives. 

Reducing the delay may still be desirable, but consideration 

should be given to the investment required to reduce the delay 

relative to overall benefits. This can be a productive way to frame 

traffic impacts related to bicycle and pedestrian projects.” Travel 

time can also be measured across modes, with average travel 

time measured by mode, and then generalized to a corridor 

average travel time per person. This metric is less useful for spot 

improvement projects or short segments.7

As mentioned above, this is only a sampling of potential 

performance metrics, and accessibility for pedestrians with 

disabilities and pedestrian safety in general should always be 

considered. Appropriate metrics for a given project will vary 

based on the project goals, project context, the design options 

under consideration, along with the available data, and should 

be considered in detail for each project. Although the term Level 

4 https://ops.fhwa.dot.gov/trafficanalysistools/index.htm

5 http://www.virginiadot.org/business/resources/TOSAM.pdf

6 https://www.oregon.gov/odot/Planning/Pages/APM.aspx

7 FHWA, 2016 Guidebook for Developing Pedestrian and Bicycle 

Performance Measures, https://www.fhwa.dot.gov/environment/bicycle_

pedestrian/publications/performance_measures_guidebook/ pg 47
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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of Service (LOS) implies similarity to the vehicular intersection 

delay rating system established in the Highway Capacity Manual, 

Bicycle LOS evaluates bicyclists’ perceived safety and comfort 

with respect to motor vehicle traffic while traveling in a roadway 

corridor. It does not measure delay and is not calibrated to assess 

the comfort of a separated bike lane. Level of Traffic Stress (LTS) 

was created to address deficiencies in the Bicycle LOS method 

such as evaluating separated bike lanes. Ultimately, a blend of 

performance metrics must be chosen and considered together in 

order to provide a full picture of the roadway operations.

Spatial Needs By Bikeway 

Intersection Type

In general, the bikeway type selected for midblock locations 

should be consistent and continuous through intersections. 

Allocating space at intersections to provide a bikeway and 

introducing design elements to limit bicyclist’s exposure and 

increase overall safety are critical objectives in the bikeway 

selection process. A clear understanding of a bikeway’s spatial 

requirements within an intersection’s functional area is critical 

to inform trade-off discussions. 

Figure 2 shows how different bikeway types approach and cross 

intersections. Each of these bikeway types at intersections have 

several permutations and allow for variability in dimensions. 

Practitioners should always consider accessibility and keep 

in mind that intersections are often a preferred location for a 

bikeway to transition from one bikeway type to another. 

Safety and Equity Focused 

Design Principles 

Intersection design should prioritize accessibility, safety and 

equity for all users. Although intersections increase conflict 

points and exposure for pedestrians and bicyclists, adopting 

a framework that prioritizes safety and equity to design and 

implement multimodal intersections can reduce conflict 

severity and frequency. The following design principles reflect 

the Sustainable Safety Principles noted in the intersection 

performance characteristics from the Bikeway Selection 

Guide (pp. 8-9). These should be referenced when planning for 

and selecting a bikeway type and designing treatments and 

interventions at intersections. Table 1 highlights additional 

sustainable safety considerations for bikeway types at 

intersections.

• Bikeway Continuity – Bikeways should not be terminated 

at intersections. They should continue through them and 

maintain the same or higher level of protection/comfort as 

approaching midblock bikeways. An equitable transportation 

system will ensure the safety and mobility needs of bicyclists 

are given equal consideration to motorists when evaluating 

spatial and operational tradeoffs that may impact the ability 

of a bikeway to be continued through an intersection.

• Minimize exposure to conflicts – Bicyclist exposure to 

conflicts with motorized traffic and pedestrians should be 

minimized. Exposure risk can rise as traffic volumes and 

operating speeds increase depending upon the bikeway 

provided. Exposure to conflicts can be eliminated using 

a variety of strategies; however, these strategies must be 

balanced against creating excessive delay or detour for each 

mode of travel as this may degrade compliance with traffic 

control devices or yielding behaviors.

• Reduce speeds at conflict points - If conflict points cannot 

be eliminated, intersection design should minimize the 

speed differential between users at the points where travel 

movements intersect. This allows users more time to react to 

avoid a crash and can reduce the severity of a potential injury 

if a crash does occur. Intersections where bicyclists operate 

should be designed to ensure slow-speed turning vehicular 

movements (10 mph or less) and weaving movements (20 

mph or less) across the path of bicyclists. Design should also 

consider interventions to slow bicyclists speeds where they 

conflict with pedestrian walkways. Common countermeasures 

may include curb extensions/bulb outs, hardened centerlines, 

truck aprons, or protected intersections. 

• Clearly communicate right-of-way – Traffic control devices 

should clearly communicate which users have the rightof-way at the intersection, including between pedestrians 

and bicyclists. Intersection geometry and operating speeds 

should support the desired yielding behavior. Common 

countermeasures may include crosswalks, regulatory signs, 

or bike signals. 

• Provide adequate sight distances - It is necessary to provide 

adequate sight distances and visibility between bicyclists, 

motorists, and pedestrians within the intersection and as 

they approach intersections. Common countermeasures 

may include curb extensions/bulb outs, parking restrictions, 

protected intersections, or warning signs.

© Toole Design
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Figure 2: Bikeway Types at Intersections

Source: FHWA
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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BIKEWAY INTERSECTION TYPE

Protected Intersection Bike Lane 

(Right Side of Travel Lane)

Pocket/Keyhole 

Bike Lane 

(Left Side of Right Turn Lane)

Mixing Zone Shared Lane

Spatial Considerations 

Bikeway Width

One-way separated bike 

lane: 6.5’-8.5’

Two-way separated bike 

lane: 10’-12’

Shared Use Path: 10’-14’

Bike Lane: 4’-7’ Bike Lane: 4’-7’

One-way separated bike 

lane approach: 6.5’-8.5’ 

Bike Lane approach: 4’-7’

No designated facility

Street Buffer Width 6’-16’ 2’-4’ (applicable for buffered 

bike lane)

2’-4’ (applicable for buffered 

bike lanes)

2’-6’ (applicable for approach 

to the mixing zone for 

separated bike lanes or 

buffered bike lanes)

N/A

Length of Approach Exposure None None* Sum of pocket/keyhole bike 

lane and merge area* Constrained to merge Area Unconstrained

Functionality (Comfort) - Roads can be categorized by their function

Perceived comfort based on 

separation from traffic and 

constrained entry/conflict 

point

High High to Moderate Moderate to Low Moderate to Low Low

Homogeneity - Roads with vehicles of balanced speeds, directions, and masses are the safest

Intersection approach 

exposure to potential motorist 

conflict

Eliminated Moderate to High Moderate to High Moderate to High High

Conflict exposure (turning and 

angle) result generally based 

upon vehicle speed/volume at 

intersection 

Low to Moderate Moderate to High Moderate to High High High

* Exposure for users in bike lanes and buffered bike lanes—defined by the lack of vertical separation—along 

intersection approach is dependent upon vehicle encroachment.

Table 1: Sustainable Safety 

Considerations for Bikeway 

Intersection Types
TRAFFIC ANALYSIS AND INTERSECTION CONSIDERATIONS TO INFORM BIKEWAY SELECTION

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BIKEWAY INTERSECTION TYPE

Protected Intersection Bike Lane 

(Right Side of Travel Lane)

Pocket/Keyhole 

Bike Lane 

(Left Side of Right Turn Lane)

Mixing Zone Shared Lane

Predictability (Right-of-Way) - Roads should be intuitive

Ability to limit or constrain 

conflicts along bikeway facility High Moderate Moderate to Low Moderate to Low Low

Right-of-way priority between 

motorists and bicyclists 

is clarified through the 

intersection

High** High to Moderate Moderate Low Low

Forgiveness (Safety) - Infrastructure can be designed to accommodate human error

Relies upon highly aware 

motorist and bicyclist behavior 

to avoid crashes

No Yes Yes Yes Yes

Bicyclists operate in separated 

space from vehicles Yes

Yes, however vehicles can 

encroach into the facility at 

any location

Yes, however vehicles can 

encroach into the facility at 

any location

Yes, prior to mixing zone; 

however, vehicles may 

encroach into facility if it is 

not separated

No

Awareness (Visibility) - Awareness improves safety for all users

Level of motorists/bicyclists 

scanning required to identify 

bicyclists, and/or motorists 

approaching from behind or 

operating beside them

Low to Moderate High High High High

** Protected intersections require careful design to ensure clear right-of-way between bicyclists and 

pedestrians and people with disabilities are fully accommodated.

Table 1 (continued)
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Traffic Analysis Assumptions and Analysis Tips

While some jurisdictions make decisions without traffic analysis, 

most require it to document the changes to the function of a 

street or intersection due to planned reconfiguration or design 

changes. Conventional traffic engineering has historically 

relied solely on motor vehicle analysis of peak hour operations 

to make transportation decisions. In many communities, this 

approach has led to streets and intersections that are often 

overbuilt and don’t support community goals. It is essential that 

practitioners think critically about traffic analysis assumptions 

and analysis approaches and evaluate how these choices 

influence the analysis outcomes and what is ultimately built. 

Rather than allowing a motor vehicle-focused analysis to 

dictate decisions, jurisdictions can use traffic analysis to 

inform the development of a transportation environment 

that the community wants – a place that supports economic 

development, allows people to walk and bike to destinations and 

supports transit use where those goals (or others) are desired. 

The sections below provide background on conventional 

analysis practices and the challenges and consequences 

associated with these practices as they relate to bikeway 

selection, and discusses how practitioners and agencies can 

adjust their assumptions and methodologies to fit within a 

holistic approach.

Volume Projections 

A common practice in traffic engineering is to use a 

“conservative” approach to estimate traffic volumes (i.e. 

higher traffic volumes) in an attempt to maximize capacity and 

minimize delay for motorists over the lifespan of a facility. While 

a conservative approach is appropriate and necessary in other 

types of engineering, like structural design, this approach in 

traffic analysis has led to street and intersection designs that 

favor motor vehicles, often resulting in undesirable outcomes: 

expensive construction projects with increased long term 

maintenance costs, higher crash rates, streets with excess 

motor vehicle capacity, and intersections that do not support 

economic activity or accommodate people walking and biking. 

Future Year

Traffic analyses often study a future condition 5 to 30 years in 

the future. Conventional traffic analysis often focuses on this 

future year condition to identify improvements to ensure that 

the street or intersection will function well for motorists in that 

future year. A challenge with this approach is that it can result 

in streets that are overbuilt for the current condition, which can 

reduce the safety performance of the roadway until such time 

as that future traffic conditions are realized. This approach also 

presumes that existing travel behaviors will remain the same 

forever and this can become a self-fulfilling prophecy, which can 

undermine community mode split goals. In situations where 

traffic increases are not realized, agencies will have increased 

their maintenance liability without realizing any benefits. Rather 

than letting this distant future year dictate decisions that are 

made, this future year should be evaluated as one of many 

scenarios for reference during the decision-making process. 

Growth Rates 

Motor vehicle traffic volume projections typically include a 

growth rate. The growth rate increases motor vehicle traffic 

volumes based on trends in historic annual average daily 

traffic (AADT) numbers, regional travel demand modeling, 

or an accepted agency practice of an assumed specific 

percentage growth per year (e.g. a growth rate of 2% per year). 

These approaches assume there will be more vehicle volume 

eventually even in locations where historic traffic trends are 

flat or declining. In locations where there has been an upward 

trend in traffic volumes, these approaches often assume past 

behavior will be indicative of future behavior even though 

modal shifts may occur due to changes in land use, expansion 

of multi-modal transportation networks, or transportation 

policies. Regional travel demand models are often deemed 

“conservative” and are also calibrated based on present or past 

travel patterns and demographics and may not adequately 

capture changes such as shifts in mode choice due to future 

unanticipated changes in the network8

 or reflect community 

desires about mode share goals. It is recommended growth 

rates align with long term community transportation goals.

8 Parthasarathi, P., Levinson, D., Post-construction evaluation of 

traffic forecast accuracy. Transport Policy (2010), doi:10.1016/j.

tranpol.2010.04.010

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Trip Generation

Trip generation tables exist to provide information for a wide 

range of development activities. These estimates are often 

based on largely suburban model trip generation rates and 

pre-internet retail use patterns, which have been proven 

to overestimate trips. The ITE Trip Generation Manual has 

expanded methodologies for trip generation in different 

contexts. Additional tools such as the Environmental Protection 

Agency’s (EPA) Mixed-Use Trip Generation Model can also 

provide useful trip generation information. Trip generation 

estimation is an art rather than a science that requires 

practitioners to evaluate the data available and determine 

whether it is appropriate for the context of their project. 

Specifically, practitioners should consider typical mode splits 

for the locality (i.e. use local mode split data if available), 

community goals for mode splits, and the likelihood of trips to 

calculate estimated trips. Much like the scenarios suggested 

in the discussion above about future year, practitioners could 

consider analysis with different trip generation scenarios to 

provide a range of results for consideration. 

KEY TAKEAWAY Streets and intersections that are designed for 

“conservative” motor vehicle volume forecasts often result in 

overbuilt streets, a design that does not meet community goals 

(e.g. safety) and are economically wasteful. Practitioners should 

estimate volume projections that are realistic and consistent 

with project or community goals for mode share. 

ANALYSIS TIP: Conduct analysis of multiple volume scenarios 

that provide a range of results to inform decisions rather than 

using one future volume forecast to dictate decisions based on 

an increase in volume that might not be realized. 

Level of Service9 (LOS)

Conventional traffic analysis exclusively uses performance 

measures for motorists like delay, LOS, volume-to-capacity, 

and queuing. Where this analysis is used to make decisions, 

the outcome will be a built environment that prioritizes motor 

vehicles. The Highway Capacity Manual emphasizes that LOS 

is a part of a bigger picture and “neither LOS nor any other 

single performance measure tells the full story of roadway 

performance” (HCM 2016, page 8-12). Practitioners should 

select performance measures that respond to project goals and 

present a holistic picture of the street or intersections being 

studied (see Performance Metrics section for additional details 

on additional performance measures). 

In addition to relying solely on motor vehicle performance 

measures, conventional traffic analysis focuses on improving 

LOS, reducing delay, and minimizing queues to levels that are 

deemed “acceptable”. It is essential that practitioners and 

agency staff are thoughtful in their interpretation of motor 

vehicle analysis results. As stated in the HCM, ‘’the existence of 

a LOS F condition does not, by itself, indicate that action must 

be taken to correct the condition” (HCM 2016, page 8-21). An 

agency or jurisdiction should consider allowing higher vehicular 

delay, higher LOS, and longer queues in the context of other 

performance measures and project goals. 

KEY TAKEAWAY Motor vehicle level of service alone does not 

fully describe the value and function of a street or intersection 

that includes all users of the roadway or purposes of the 

roadway and surrounding landuse. Practitioners should select 

performance measures that respond to project goals (see 

Performance Measures section). 

ANALYSIS TIPS: 

• For motor vehicle queues, evaluate the 50th-percentile queue 

in addition to the 95th percentile queue. 

• When interpreting results, practitioners should consider whether 

a LOS F (or other conventional standard) may be acceptable 

during certain peak hours if other project goals are achieved. 

Time Period and Analysis Period

Conventional traffic analysis typically uses volumes from 

a one or several one-hour time period(s) during peak hours 

(typically AM and PM peak hours of a weekday) to evaluate the 

movement of the largest traffic volumes. These peak hours are 

typically taken during a peak period of the week (e.g. Tuesday, 

Wednesday or Thursday), and year (e.g. when school is in 

session). Additionally, conventional traffic analysis also often 

uses a Peak Hour Factor (PHF) to convert hourly volumes 

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to peak 15-minute flow rates, effectively using a 15-minute 

analysis period. Finally, in some cases, jurisdictions require 

that PHF for individual approaches or movements are used. 

This assumes that the peak 15-minutes of each approach 

overlaps with each other, which may not be the case. All these 

factors can compound together resulting in volumes that 

are the peak of the peak being studied, rather than typical or 

average values. The consequence of these approaches is like 

those described in the section on volume projections: streets 

are overbuilt and often don’t support community goals. At a 

minimum, practitioners should collect data outside of the peak 

hours being studied to understand how the peak hour volumes 

compare to off peak volumes. This understanding can be 

helpful when evaluating results and making decisions about 

the changes to the intersection like turn lanes, maintaining a 

bike lane through an intersection, separate bike phasing, etc. 

An alternate approach is to use an average of volumes over a 

2-3-hour peak period rather than a single peak hour – this would 

be an average peak period analysis rather than a peak hour 

analysis. Practitioners should also consider using a peak hour 

factor for the intersection rather than for individual movements 

or approaches. 

KEY TAKEAWAY People use streets at all hours of the day and 

night and the use of street varies throughout the entire day; 

streets should be designed for all day use, not just a single peak 

hour (or even peak 15- minutes). 

ANALYSIS TIPS: 

• Use a peak hour factor based on the entire intersection, not 

specific movements. 

• Collect data for a 2-3-hour peak period at a minimum or, 

ideally, a 24-hour period to understand the demands of the 

street throughout the day. Consider averaging 2-3-hour peak 

to analyze an average peak hour. 

Network Utilization/Peak Spreading

When balancing vehicular delay and operations against 

dedicating additional space to a safer and more comfortable 

bikeway, a practitioner should consider whether parallel network 

capacity could accommodate a portion of the existing vehicle 

traffic. This may include analysis that considers the impact of 

a change in the network or improvement of an intersection that 

is “outside the study area” which if built, would help address 

capacity constraints within the study area. Expanding the study 

area or gathering origin destination data can help practitioners 

to understand how the available network could best be used. 

In cases where a larger study is not feasible, agencies can 

consider an intersection level sensitivity analysis to understand 

the level of vehicular traffic that would need to shift to other 

routes in order to maintain the levels established by performance 

metrics. The sensitivity analysis could also evaluate the number 

of vehicles that would need to shift to other time periods 

(sometimes as little as 15 minutes) or to other modes. 

KEY TAKEAWAY When intersection or corridor projects are 

evaluated in isolation, the broader context of the surrounding 

network is lost. 

ANALYSIS TIP: In locations with constrained right-of-way and 

congested operations, practitioners should look beyond the 

defined study area to determine if there are viable alternate 

routing choices available for motorists. Additionally, there is 

often additional capacity outside the peak hour being studied 

where a shift of volumes by even just 15 minutes can provide 

some relief to motorists. 

Signal Timing Assumptions 

Green Interval

When the green interval is determined only on the basis of 

motor vehicle traffic, it may not be sufficient for bicyclists who 

have longer start-up times and slower travel speeds. This is 

particularly an issue for larger intersections, intersections 

that are on steeper grades, or where bicyclists may be queued 

further back from the intersection. In these locations, the green 

interval may need to be longer for stopped bicyclists to proceed 

and clear the intersection before the light changes.  Where 

practitioners are trying to optimize intersection operations, 

bicycle detection may be used to extend the green interval 

when bicyclists are present to ensure bicyclists can clear the 

intersection safely.

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Yellow Change and Red Clearance Intervals

When the yellow change and red clearance intervals are 

determined only on the basis of motor vehicle traffic, they 

may not be sufficient for bicyclists who have different braking 

characteristics or who travel at slower speeds. This is 

particularly an issue for larger intersections and intersections 

that are on steeper grades. These intervals may need to be 

longer to allow a bicyclist who is approaching the intersection 

at speed near the end of the green interval.  If the yellow change 

and red clearance intervals are too short, the bicyclist may still 

be traversing the intersection when the conflicting traffic gets a 

green indication. Where practitioners are trying to optimize the 

intersection operations, bicycle detection may be used to extend 

these intervals only when bicyclists are present. The MUTCD 

says, “The duration of a red clearance interval may be extended 

from its predetermined value for a given cycle based upon the 

detection of a vehicle that is predicted to violate the red signal 

indication.”

KEY TAKEAWAY Signal timing parameters may require 

adjustment to accommodate all users. 

ANALYSIS TIPS:

• Practitioners should consider the operating characteristics 

of the expected user of a facility and adjust assumptions 

accordingly.

• For signal progression, consider using a lower progression 

speed when setting signal offsets in order to accommodate 

more efficient bike travel through a corridor (12-15 mph).

Discussion Prompts

Below are some specific questions to consider during 

operational analysis in support of bikeway selection at a 

constrained intersection. 

Volume Projections

• Are motor vehicle volume projections realistic or are they 

considered “conservative”? Do they rely heavily on individual 

land uses from the ITE Trip Generation Manual? 

• What are volume projections based on?

• Are volume projection timelines required or a design decision? 

• Do they reflect the mode share and potential mode shift 

to more people biking with the implementation of a more 

complete, comfortable bike network? 

• Do they reflect the mode share and potential mode shift to 

more people walking with the implementation of a more 

complete, comfortable and accessible pedestrian network? 

• What are the future mode share goals? How would this 

intersection function/look if those goals were met?

Level of Service

• Does prioritizing motor vehicle level of service result in either 

dropping the bikeway or using a mixing zone treatment 

rather than continuing a high-comfort bikeway through the 

intersection?

• Can a lower motor vehicle LOS be accepted during the peak 

hour so that a high-comfort bikeway can be continued through 

the intersection? 

• How sensitive is the LOS to changes in the peak volume? 

What is the off-peak LOS? 

• How will LOS assumptions impact the overall intersection 

footprint? Achieving desirable motor vehicle LOS in the peak 

hour may require a larger intersection footprint. This larger 

footprint results in a less efficient intersection, increases 

pedestrian crossing distances, especially during off peak hours, 

and uses land that could otherwise be open space or developed. 

• Determine a maximum amount of single occupant vehicle 

traffic that is desirable and what would be necessary to 

achieve it to start the process.

Analysis Period

• Does the analysis evaluate the peak 15 minutes for individual 

intersection approaches, which may not actually occur at the 

same time in practice? An analysis that assumes a more even 

distribution of traffic over the hour will be more representative 

of what a typical driver might experience. 

• How long is the peak period? Is this peak period volume 

desirable and compatible with other goals for this area?

• If pedestrian or bicycle peak periods occur at a different time, 

consider studying those time periods as well.

Network Utilization/Peak Spreading

• Is there a parallel or alternate route that motorists could use if 

delay is high at an intersection? 

• Is traffic volume data up to date for surrounding streets and 

intersections to assist with network utilization analysis?

• Are there parallel or alternate route that could accommodate 

a low-stress bikeway and still provide access to key 

destinations?

• If a movement or movements are experiencing some delay 

during the peak hour, is it possible that some of that traffic could 

shift outside the peak hour, but still within the peak period? 

Accessibility

• Can bicyclists and pedestrians cross existing uncontrolled 

crossings, or is additional traffic control necessary?

• Does the design provide accessibility to all users, particularly 

people with disabilities, pedestrians and bicyclists of all ages 

and abilities?
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Conclusion

This document is a supplemental resource to help 

transportation practitioners make informed decisions about 

the trade-offs in bikeway selection specific to intersections. 

It focuses on traffic analysis because this often frames and 

constrains discussions about intersections. It builds upon the 

guidance in the Bikeway Selection Guide and includes helpful 

references to specific design and planning guidance.

Intersection related considerations, particularly in locations 

with limited right-of-way, have the potential to dominate the 

conversation on bikeway selection, but pedestrian safety, the 

need to ensure accessibility, and project goals should always 

be in the forefront of the conversation. This resource presents a 

broad range of metrics that can be used in design evaluations, 

and outlines approaches for traffic and operational analysis. It 

relates this information back to design principals and options 

for bikeway selection at intersections to encourage holistic 

decision-making in the planning process as part of systemic 

safety approach that is tailored to community goals and meets 

the needs of people of all ages and abilities. 

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