1 / 22

# CE 578 Highway Traffic Operations - PowerPoint PPT Presentation

CE 578 Highway Traffic Operations. Lecture 4: HCM Directional Analysis. Objectives. Understand two-lane highway performance measures Relate two-lane highway conditions to input variables Calculate adjusted volume Calculate performance measures ATS PTSF.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about ' CE 578 Highway Traffic Operations' - meredith-poole

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### CE 578 Highway Traffic Operations

Lecture 4: HCM Directional Analysis

• Understand two-lane highway performance measures

• Relate two-lane highway conditions to input variables

• Calculate performance measures

• ATS

• PTSF

• Percent-time-spent-following (PTSF)

• Average travel speed (ATS)

• Average travel time

• Passing supply vs passing demand

• Precept—Mobility

• Consistent high speed

• Infrequent passing delays

• Precept—Access

• Infrequent passing delays

• Freedom to maneuver

• Safety

• Speed not a primary concern

• Different highways and different expectations

• Primary arterials: serve long distance trips, major inter-city travel, daily commuter routes, high travel speed expected

• Secondary roadways: high speed not expected, scenic route, rugged terrain, recreational route, short trips, trip ends

• Class I: PTSF and ATS

• Passing delay is expected to be at a minimum

• High speed is expected

• Class II: PTSF

• Higher levels are acceptable but drivers are still sensitive to this measure

• ATS is generally not an issue

• Drivers will not be on the highway long

• Or do not expect high speeds

• Microscopic simulation

• TRAR

• TWOPAS

• Deterministic procedures

• US HCM two-way methodology (not necessary)

• US HCM directional methodology

Input Highway

Conditions

Calculations

Compute

Performance

Measure(s)

• 12 ft lanes

• 6 ft shoulders

• No no-passing zones

• 100% passenger cars

• No impediments to through traffic

• Level terrain

• 50/50 traffic split by direction

Base Condition PTSF Estimation: Graph (50/50 directional split)

• Relative to two-way analysis procedure

• Split traffic by direction

• Analyze each direction of traffic separately

• Volume adjustments are the same for general terrain

• ATS

• Equation 20-15

• PTSF

• Coefficients for BPTSF (use 20-21)

• Equations 20-16 and 20-17

(take care to use analysis direction flow and opposing flow, not two-way flow)

• No change in volume adjustments

• No change in ATS calculation

• PTSF calculation

• Same BPTSF equation

• New PTSF equation

• New BPTSF coefficients

• See Table 9 (handout)

• New adjustments  replacing fnp

• See Table 10 (handout)

• Given:

• class I highway with base conditions,

• vd = 750 pcph,

• vo = 450 pcph,

• no no-passing zones,

• FFS of 60 mph

• 50/50 directional split

• Find

• ATSd

• PTSFd and

• LOS

• Given

• Class I

• V = 600 vph

• Terrain = Rolling

• 60/40 split

• 60% no-passing zones

• PHF = 0.90

• 10% Trucks 5% RVs

• FFS = 65 mph

• ATS

• See HCM 2000 Chapter 20 pp 20-12 and 20-29

• PTSF

• See HCM 2000 Chapter 20 pp 20-12 and 20-29

• HCM 2000 two-way vs HCM 2000 directional (combined)

• ATS

• ATSc = 56 mph; ATStwo-way = 56.5 mph

• PTSF

• PTSFc = 81.8; PTSFtwo-way = 62.7

• Is this significant?

• How to combine directional performance estimates into a two-way estimate

• How to implement modified HCM procedure to maintain consistency with two-way analysis

• How to perform an iteration to maintain consistency between the factors and the adjusted volumes.

• Limitations of HCM methodologies (stay tuned)

• See website for the problems and solutions

• Sensitivity to highway section length

• Intersection operations

• Capacity conditions