Network Analysis Reference ¶

This page provides comprehensive technical reference documentation for TM2PY network analysis capabilities.

Highway Network Attributes ¶

Complete Attribute Reference ¶

Source: Actual TM2PY Bay Area database export
File: scripts/emme_link_attributes.txt

The TM2PY highway network contains 85 link attributes extracted from the actual Bay Area EMME database:

Core Performance Attributes ¶

auto_volume - Total automobile volume
auto_time - Congested travel time (minutes)
@free_flow_time - Free flow travel time (minutes)
@capacity - Link capacity (vehicles/hour)
@ft - Facility type code
length - Link length (miles)

Vehicle Type Flows ¶

@flow_da - Drive alone flow
@flow_sr2 - Shared 2-person flow
@flow_sr3 - Shared 3+ person flow
@flow_trk - Truck flow

Cost and Performance ¶

@cost_da - Drive alone cost
@bridgetoll_da - Bridge toll costs
@reliability - Reliability measure

→ View complete attribute list

Database Structure ¶

Location: E:\2015-tm22-dev-sprint-04\emme_project\Database_highway\emmebank
Network Size: 839,834 links per scenario
Scenarios: 6 time periods (EA, AM, MD, PM, EV, EA2)

Facility Type Classification ¶

Code	Facility Type	Description
1	Freeway	Interstate highways and freeways
2	Freeway	Principal arterial - freeway facilities
3	Arterial	Principal arterial roads
4	Arterial	Minor arterial roads
5	Collector	Major collector roads
6	Collector	Minor collector roads
7	Local	Local streets and roads
8	Connector	Highway ramps and connectors
99	Other	Special facilities and other links

Transit Network Attributes ¶

Complete Attribute Reference ¶

Source: TM2PY source code analysis

Transit Line Attributes ¶

line.id - Transit line identifier
line.mode.id - Mode character (‘b’, ‘l’, ‘h’, ‘r’, ‘f’, ‘e’)
line.headway - Service headway in minutes
line.vehicle.total_capacity - Total vehicle capacity
line["#description"] - Line description/name
line["#src_mode"] - Source mode for fare calculations
line["#faresystem"] - Fare system ID (1-50)

Transit Segment Attributes ¶

segment.transit_volume - PRIMARY passenger volume/boardings
segment.transit_boardings - Alternative boarding attribute
segment.dwell_time - Dwell time at stops (minutes)
segment.link.length - Segment length (miles)

Transit Mode Classification ¶

Code	Mode	Description
b	Local Bus	Local bus service (modes 10-99)
e	Express Bus	Express bus service (modes 80-99)
l	Light Rail	Light rail transit (modes 110-119)
h	Heavy Rail	Heavy rail/subway (modes 120-129)
r	Commuter Rail	Commuter rail service (modes 130-139)
f	Ferry	Ferry service (modes 100-109)

Analysis Tools ¶

Network Summary Script ¶

Location: scripts/network_summary.py

Enhanced script providing comprehensive highway network analysis:

Input Validation: 5-phase validation of database structure and data quality
Highway Analysis: VMT, VHT, delay calculations by facility type and time period
Comprehensive Logging: Detailed progress reporting and diagnostic information

📖 → View Complete Usage Guide

Transit Network Attributes ¶

Transit Network Structure ¶

Location: E:\2015-tm22-dev-sprint-04\emme_project\Database_transit\emmebank
Scenarios: 6 time periods matching highway (EA, AM, MD, PM, EV, EA2)
Network Elements: Transit lines, segments, and nodes

Transit Line Attributes ¶

Primary Service Attributes: - line.id - Unique line identifier - line.headway - Service headway (minutes between vehicles) - line.vehicle.total_capacity - Total vehicle capacity (standing + seated) - line.vehicle.seated_capacity - Seated vehicle capacity only - line.mode - Service mode (bus, rail, etc.)

Calculated Service Metrics: - Hourly Total Capacity: 60 × total_capacity ÷ headway - Hourly Seated Capacity: 60 × seated_capacity ÷ headway - Service Frequency: 60 ÷ headway (vehicles per hour)

Transit Segment Attributes ¶

Ridership Data: - segment.transit_volume - PRIMARY passenger boardings per hour - segment.dwell_time - Vehicle dwell time at stops (minutes) - segment.transit_time_func - Transit travel time function code

Geographic Attributes: - segment.i_node.id - Origin node ID
- segment.j_node.id - Destination node ID - segment.link.length - Segment length (miles)

Additional Data Fields: - segment.data1 - Custom data field 1 - segment.data2 - Custom data field 2
- segment.data3 - Custom data field 3

Transit Mode Classification ¶

TM2PY Mode Coding: | Mode ID | Mode Type | Description | Service Characteristics | |---------|-----------|-------------|------------------------| | 10-39 | Local Bus | Local bus service | Frequent stops, moderate speed | | 40-79 | Limited Bus | Limited-stop bus | Fewer stops, higher speed | | 80-99 | Express Bus | Express bus service | Minimal stops, freeway operation | | 100-109 | Ferry | Ferry service | Water-based transit | | 110-119 | Light Rail | Light rail transit | Electric rail, grade separation | | 120-129 | Heavy Rail | Heavy rail/subway | Grade-separated rapid transit | | 130-139 | Commuter Rail | Commuter rail | Regional rail service |

Transit Performance Metrics ¶

Ridership Metrics: - Line Boardings: Sum of segment.transit_volume across all segments - Segment Boardings: Individual segment.transit_volume values - Daily Boardings: Sum across all time periods for all-day totals

Capacity Utilization: - Load Factor: boardings ÷ hourly_total_capacity - Seated Load Factor: boardings ÷ hourly_seated_capacity - Peak Load Point: Maximum boardings along line route

Service Productivity: - Boardings per Route Mile: total_boardings ÷ total_route_length - Passengers per Vehicle Hour: boardings ÷ (vehicles_per_hour) - Revenue per Mile: Ridership-based efficiency metric

Coverage Metrics: - Route Miles: Total length of transit routes - Line Count: Number of unique transit lines - Segment Count: Number of route segments with service

Analysis Tools ¶

Network Summary Script ¶

Location: scripts/network_summary.py

Enhanced script providing comprehensive multimodal network analysis:

Input Validation: 6-phase validation of highway and transit database structure
Highway Analysis: VMT, VHT, delay calculations by facility type and time period
Transit Analysis: Boarding volumes, ridership patterns, and service performance
Comprehensive Logging: Detailed progress reporting and diagnostic information

Performance Metrics ¶

Highway Network Metrics ¶

VMT: Vehicle Miles Traveled = Volume × Link Length
VHT: Vehicle Hours Traveled = Volume × Travel Time
Delay: Additional time due to congestion = Volume × (Congested Time - Free Flow Time)
Speed: Average travel speed = VMT / VHT

Transit Performance Metrics ¶

Core Ridership Metrics: - Boardings: segment.transit_volume - Passengers boarding at each segment - Line Boardings: Sum(segment.transit_volume) - Total boardings per line - Daily Boardings: Sum across all time periods for all-day totals - Mode Boardings: Aggregated ridership by service type

Capacity and Service Metrics: - Line Capacity: 60 × vehicle.total_capacity ÷ headway (passengers/hour) - Seated Capacity: 60 × vehicle.seated_capacity ÷ headway (seated passengers/hour) - Service Frequency: 60 ÷ headway (vehicles per hour) - Load Factor: boardings ÷ line_capacity (utilization ratio)

Productivity and Efficiency: - Boardings per Route Mile: total_boardings ÷ route_length - Passenger Miles: boardings × segment_length - Revenue Miles: Total route distance operated - Passengers per Vehicle Hour: Service efficiency metric

Geographic Coverage: - Route Miles: Sum(segment.link.length) by line/mode - Service Area: Geographic extent of transit coverage - Stop Density: Stops per route mile - Network Connectivity: Transfer opportunities and accessibility

Usage Guidelines ¶

For Developers ¶

Reference attribute files when writing analysis code
Use consistent transit attribute naming: transit_volume is primary boarding attribute
Follow multimodal analysis patterns established in network summary script
Implement proper validation for both highway and transit databases

For Analysts ¶

Use network summary script for comprehensive multimodal performance analysis
Access detailed attribute documentation for custom analysis
Validate results against expected ranges for Bay Area highway and transit networks
Consider both modes when evaluating transportation system performance

For Documentation Maintenance ¶

Keep attribute files synchronized with database changes
Update transit mode classifications as service types evolve
Maintain consistency between highway and transit documentation standards
Document any changes to ridership data sources or calculation methods