1. “Bringing Back-of-the-Envelope Back”
HCM – 6th Edition
Planning and Preliminary Engineering Applications Guide (PPEAG) to the HCM
“Bringing Back-of-the-Envelope Back”
April, 2017

2. Potential Use of the HCM in Planning
The HCM is commonly used to evaluate current or forecast roadway operations
The HCM can also reliably and cost-effectively support:
Planning efforts
Programming decisions
Performance monitoring
Roadway management
According to the introduction to the Guide, the Highway Capacity Manual (HCM) is commonly used by transportation agencies to evaluate the current or forecast operations of roadway facilities. Less well known is that the HCM can also be used to cost-effectively and reliably support agencies’ planning, programming, and management decisions.
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3. Actual Use of the HCM in Planning
State DOTs, MPOs, local governments, and others were surveyed
Less-experienced users less likely than expert users to see value in using the HCM for planning
More use with short-term than long-term planning
A survey described in Naitonal Cooperative Highway Research Program Synthesis 427, Extent of Highway Capacity Manual Use in Planning, provided valuable insights on how the HCM is and is not used for planning. Less-experienced users—those who had a self-described familiarity with the HCM ranging from little to average—were less likely to see value in using the HCM for planning. This suggests that more education is needed to familiarize less-experienced professionals with the potential benefits of using the HCM in planning. When the HCM was used for planning, it was more often in the context of short-term planning (where more inputs to HCM procedures would be known with certainty) than for long-term planning. Note that at the time the survey was made, users were familiar with the HCM2000; the HCM 2010 was released a couple of months after the survey.

4. Users’ Desired HCM Improvements for Planning
Develop a P&PE Applications Guide (77%)
Provide travel time reliability measures (63%)
Extend HCM to system & corridor analyses (63%)
Integrate HCM methods better with travel demand models (60%)
Provide systemwide MOEs (60%)
The most-desired HCM improvement among the survey respondents was to develop an applications guide showing how the HCM could be applied to typical planning and preliminary engineering tasks. As discussed in another briefing, the HCM now provides travel time reliability measures. The HCM2000 provided some rudimentrary system and corridor methods, but they required software to be developed to make them practical and therefore received little use and were dropped in the HCM Other desired improvements included better integration of the HCM with travel demand models and guidance on estimating systemwide measures of effectiveness such as vehicle-hours or person-miles of travel.

5. Audiences for the Guide
Regular HCM users
Planning or preliminary engineering–level analyses with limited available data
Questions requiring a quick, reasonable answer
Planners who may not be aware of the HCM or consider themselves HCM users, but who can nevertheless use it for portions of their work
Coordinated use of the HCM with planning models and tools
Integration of HCM methods and defaults into planning tools
System performance monitoring

6. Focus of the Guide Multi- facility Single facility, point
The Guide focuses on mid- and high-level analysis methods that either apply the HCM directly or are “HCM-based”—applying simplifications to a method described in the HCM to make it more usable in a planning context (balancing data needs and computational resources with the required accuracy for an analysis.

7. Guide’s Relationship to the Project Life Cycle
A roadway project goes through many stages from concept to construction to operation. Initially, the potential need for a project is identified through a long- or short-range areawide or corridor-based plan. Later, if selected for further development and if funding is available, a project will move into the project initiation and project clearance stages, and facility-specific project and environmental plans will be developed. Once the project moves into final design, it moves out of the realm of planning and preliminary engineering. However, once the project is constructed and in operation, it becomes part of the overall transportation system and a subject for system performance monitoring. As performance monitoring covers large areas at low levels of precision, planning and preliminary engineering techniques for estimating roadway operations performance measures again become applicable.

8. Part 2: Medium-Level Analysis
Guide Outline
Part 1: Overview
Gateway to the Guide for non-HCM users
Information cross-referenced throughout the Guide
Part 2: Medium-Level Analysis
Gateway to the Guide for current HCM users
Planning tools for HCM system elements (points, segments, facilities)
Part 3: High-Level Analysis
Guidance on extending the HCM to corridors, areas, and transportation systems
Part 4: Case Studies
Recognizing the breadth of the Guide’s target audience, the Guide has been structured so that it can been approached in different ways. Importantly, the Guide is designed as a reference work that is not intended to be read cover to cover. Non-HCM users access the Guide via Part 1, while HCM users are referred to appropriate parts of the Guide directly from the HCM. These gateways then refer readers to appropriate sections in Parts 1–4 for more information and examples. In addition to providing an overview of the Guide, Part 1 provides sections on topics cross-referenced throughout the Guide. Part 2 is divided into sections corresponding to HCM system elements (e.g., freeway facilities or signalized intersections), plus sections on multimodal analysis and truck level of service. Part 3 provides guidance on extending the HCM to larger study areas, including corridors, areas, and entire transportation systems. Finally, Part 4 provides three case studies demonstrating many of the methods provided in the Guide. The remainder of this web briefing will cover each parts in detail.

9. Organization of the Guide
Part 2: Medium-Level Analysis (Sections H–P)
Entry point to the guide for HCM users
HCM 6th Edition refers readers to specific guidebook sections
Organized by HCM system element
Freeways, two-lane highways, urban streets, etc.
Plus bicycles, pedestrians, transit, and truck (freight) modes
Typical subsections
Scoping and screening method
HCM method with defaults
Alternate or extended HCM method

10. L. Signalized Intersections M. Stop-Controlled Intersections
Part 2 Outline
H. Freeway Analyses
I. Multilane Highways
J. Two-Lane Highways
K. Urban Streets
L. Signalized Intersections
M. Stop-Controlled Intersections
N. Roundabouts
O. Pedestrians, Bicyclists, and Public Transit
P. Truck Level of Service
Part 2 contains 9 sections and is likely to be the first point of entry to the Guide for regular users of the HCM. Each HCM chapter presenting an analysis methodology cross-references the Part 2 section in the Guide that contains the corresponding planning guidance and methods. Sections H–N each cover one of the main types of HCM roadway system elements from the perspective of motorized vehicle operations. They are structured similarly and we’ll look at them as a group in a moment. Section O provides planning methods for the pedestrian, bicycle, and public transit modes for all of the system elements for which the HCM provides methods. Finally, Section P presents a method for estimating truck level of service that fills a gap in the HCM’s analysis toolbox.
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11. Most HCM operations methods require specialized software to implement
Simplified HCM Method
Most HCM operations methods require specialized software to implement
Many target users of the Guide won’t have access to this software
Using the HCM method with defaults may require more resources than available or appropriate for the analysis
The Guide presents simplified methods that are HCM-compatible, but can be performed by hand or implemented in a basic spreadsheet
Multiple performance measures can be calculated
Simplified methods available for all system elements
Many target users of the Guide won’t have access to specialized software implementing HCM methods. Even when software is available, it may require more data collection than is feasible or appropriate for the level of analysis being conducted. Consequently, the Guide presents simplified HCM methods for each of the system elements covered in the Guide. These methods are based on HCM methods, but unlike most full HCM methods, the calculations can be performed by hand, implemented using formulas in a spreadsheet (no macro programming required), or incorporated as a calculation routine in another analysis tool. Multiple performance measures can be calculated and the analyst need only provide the data required to calculate the performance measures of interest, as opposed to the data required to calculate the full suite of measures produced by an HCM method.

12. Most HCM operations methods require specialized software to implement
Simplified HCM Method
Most HCM operations methods require specialized software to implement
Many target users of the Guide won’t have access to this software
Using the HCM method with defaults may require more resources than available or appropriate for the analysis
The Guide presents simplified methods that are HCM-compatible, but can be performed by hand or implemented in a basic spreadsheet
Multiple performance measures can be calculated
Simplified methods available for all system elements
Many target users of the Guide won’t have access to specialized software implementing HCM methods. Even when software is available, it may require more data collection than is feasible or appropriate for the level of analysis being conducted. Consequently, the Guide presents simplified HCM methods for each of the system elements covered in the Guide. These methods are based on HCM methods, but unlike most full HCM methods, the calculations can be performed by hand, implemented using formulas in a spreadsheet (no macro programming required), or incorporated as a calculation routine in another analysis tool. Multiple performance measures can be calculated and the analyst need only provide the data required to calculate the performance measures of interest, as opposed to the data required to calculate the full suite of measures produced by an HCM method.

13. Example Data Requirements for the Simplified Signalized Intersection Method
Performance Measure
Input Data (units)
Cap
Del
LOS
MMLOS
Que
Default Value
Number of turn lanes •
Must be provided
Other geometry
HCM Exhibit 19-11
Signal timing
HCM Exhibits and 19-17
Peak hour factor (decimal)
0.90 (total entering volume <1,000 veh/h), 0.92 (otherwise)
Percentage heavy vehicles (%) 3%
Parking activity
None
Pedestrian activity
Volumes by movement (veh/h)
Analysis period length (h)
0.25 h
This table from the Guide compares the data requirements for estimating different performance measures for signalized intersections using the Guide’s simplified method. In contrast, the table of data requirements for the full HCM operations method is more than a page long. Of the required data, only one or two items must be provided by the analyst (number of turn lanes and turning movement volumes), while the remaining inputs can be defaulted if the corresponding data are not available to the analyst. In the case of the signalized intersection method, the Guide provides step-by-step calculations for estimating capacity, delay, auto level of service, multimodal level of service, and queue lengths. The calculations can be implemented in a spreadsheet, or performed by hand using the worksheets provided in the Guide. The goal of the simplified methods is to provide reasonably accurate results with much less data collection and compuational effort.
Cap = capacity, Del = delay, LOS = motorized vehicle level of service, MMLOS = multimodal level of service, Que = queue length

14. Section Analysis Using the HCM with Defaults
Applies the HCM operations method, but using default values for many inputs to reduce data requirements
Requires access to HCM-implementing software
Guide provides information on what input data are needed to apply the method
Guide suggests default values for inputs that can be defaulted
Applicable system elements:
Freeways, multilane highways, two-lane highways
Urban streets
Regular HCM users typically have access to software that implements the HCM operations methods for various system elements. In these cases, a planning or preliminary engineering analysis can be performed by substituting default values for many or all of the inputs that are not required to be provided (such as demand volumes or number of lanes). The Guide provides tables that compare the data required for an HCM analysis using defaults (with software) and a simplified HCM analysis (by hand, by spreadsheet, or a calculation incorporated into another analysis tool). These tables also suggest default values for inputs that can be defaulted; some tables provide more suggested defaults than the HCM itself provides.

15. Other Topics: Sections H–N
Freeways
Method adaptations for advanced freeway management practices
Urban streets
Method extension to over-capacity conditions
Many target users of the Guide won’t have access to specialized software implementing HCM methods. Even when software is available, it may require more data collection than is feasible or appropriate for the level of analysis being conducted. Consequently, the Guide presents simplified HCM methods for each of the system elements covered in the Guide. These methods are based on HCM methods, but unlike most full HCM methods, the calculations can be performed by hand, implemented using formulas in a spreadsheet (no macro programming required), or incorporated as a calculation routine in another analysis tool. Multiple performance measures can be calculated and the analyst need only provide the data required to calculate the performance measures of interest, as opposed to the data required to calculate the full suite of measures produced by an HCM method.

16. Section P: Truck Level of Service
The HCM doesn’t provide a truck LOS measure
NCFRP Report 31 does, and it has been incorporated into the Guide
Truck LOS is based on the degree to which a roadway provides ideal truck conditions
Usable by trucks with legal size and weight loads
No at-grade railroad crossings
Provides reliable truck travel at truck free-flow speeds
Low cost (i.e., no tolls)
The HCM does not yet provide a truck LOS measure. However, such a measure has been developed through research and is presented in National Cooperative Freight Research Program Report 31, Incorporating Truck Analysis Into the Highway Capacity Manual. The Guide describes the data requirements and calculation steps for the method, which can be implemented by hand or in a spreadsheet. Truck LOS is based on the degree to which a roadway provides ideal truck conditions, as defined above.

17. Organization of the Guide
Part 3: High-Level Analysis (Sections Q–S)
Extensions of the HCM to larger study areas
Corridors
Areas and systems
Systemwide performance monitoring

18. Peak-Hour Peak-Direction (veh/h/ln) AADT (2-way veh/day/ln)
Scoping and Screening
Applying generalized service volume tables
Developing service volumes
Applicable system elements:
Freeways
Multilane highways
Two-lane highways
Urban streets
Scoping and screening methods involve either the application of existing service volume tables, or determining the maximum volume that can be served at a given level of service. The Guide provides service volume tables for freeways, multilane highways, two-lane highways, and urban streets.
Area
Type
Terrain
Peak-Hour Peak-Direction (veh/h/ln)
AADT (2-way veh/day/ln)
LOS A-C
LOS D
LOS E
(capacity)
Urban
Level
1,550
1,890
2,150
14,400
17,500
19,900
Rolling
1,480
1,810
2,050
13,700
16,700
19,000
Rural
1,460
1,770
2,010
12,100
14,800
16,800
1,310
1,600
1,820
11,000
13,400
15,200

19. Milwaukee CBD Signalized Intersection Hourly Service Volume Tables
Roadway Type
# of Lanes
Service Volumes
(per direction) A B C D E
Undivided Roadway
Two-way w/ Parking 1*
---
250
390
440
480 2
560
720
770
800
Two-way w/o Parking
330
490
550
590
610
820
850
One-way w/ Parking (1 side)
740
1060
1160
1250 3
1170
1620
1750
1860 4
1650
2210
2370
2520
One-way w/ Parking (2 sides)
1030
1130
1210
1140
1580
1710
1820
2180
2340
2490
One-way w/o Parking
810
1150
1260
1350
1240
1700
1840
1950
1720
2300
2470
2620

21. Section Q: Corridor Quick Estimation Screenline Analysis
Quick method for assessing corridor capacity
More-detailed assessments would use Section R (area) techniques or facility-specific methods from Part 2
The performance of a freeway–arterial corridor system and its components are often estimated through a travel demand and analysis forecasting process combined with either a microscopic or macroscopic traffic operations model. This process requires a variety of inputs and outputs which the HCM can provide, including capacity, queues, delay, travel speeds, and level of service. Section Q provides a quick, high-level method for assessing corridor capacity. A more-detailed, but still planning-level assessment can be conducted using either the area techniques discussed in Section R or the facility-specific methods from Part 2.

22. Section R: Areas and Systems
Area- and systemwide analysis is typically performed in a travel demand modeling environment
Section R provides guidance on:
Using HCM procedures to generate the key performance analysis inputs required by typical demand models
Post-processing demand model output to generate additional performance measures
Although the HCM is not typically used directly for area- and systemwide analysis, it can be applied during a travel demand modeling process to both develop more-accurate capacity inputs to the model and to generate additional performance measures not directly output by the model. Section R provides guidance on both these aspects of area- and systemwide analysis.

23. Section S: Roadway System Monitoring
Guidance on identifying and diagnosing travel-time reliability and capacity problems
Method assumes that the agency has access to archived average travel times by road segment and time of day
The travel time index, the ratio of actual to free-flow travel time, is a useful indicator of congestion problem spots
Florida DOT
Section S provides guidance on calculating a roadway segment’s travel time index from archived travel time data and interpreting the results in terms of whether a roadway link is likely, possibly, or unlikely to be congested.

24. Part 4: Case Studies (Sections T–V)
In-depth examples of applying the Guide’s methods
Freeway master plan
Arterial bus rapid transit analysis
Long-range transportation plan

25. HCMAG Outreach The Guide can be downloaded from HCM Volume 4
Free, one-time registration required
Five spreadsheet computational engines provided on Volume 4 to help implement some of the Guide’s methods
Upcoming HCMAG Webinars Sponsored by TRB
Planning and Preliminary Engineering Applications Guide to the Highway Capacity Manual: Part 1, Contents (May 30, 2017)
Planning and Preliminary Engineering Applications Guide to the Highway Capacity Manual: Part 2, Applications (June 28, 2017)