4.4 Transportation Systems Management and Operations (TSMO) & Regional ITS

Transportation Systems Management and Operations (TSMO) & Regional ITS

Transportation Systems Management and Operations (TSMO) is an integrated, performance-driven approach to optimize the performance of existing transportation infrastructure through active operational management. Rather than relying solely on high-cost physical capacity expansion (adding lanes), TSMO deploys multimodal, cross-jurisdictional systems and Intelligent Transportation Systems (ITS) technologies to improve safety, reduce congestion, and enhance travel time reliability.

1. TSMO Core Strategies & Travel Time Reliability Metrics

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|                         ACTIVE TSMO STRATEGIES                              |
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| Strategy                   | Operational Mechanism & Benefits               |
+----------------------------+------------------------------------------------+
| Active Traffic Management  | Dynamically adjusts freeway speed limits, lane |
| (ATM / VSL)                | assignments, and shoulder use based on sensors.|
| Dynamic Lane Assignment    | Overhead lane control signs (green arrow, red X|
| (DLA)                      | yellow diagonal) guide traffic around lane cuts|
| Hard Shoulder Running (HSR)| Opens paved shoulder as temporary travel lane  |
| / Part-Time Shoulder Use   | during peak hours or incident diversion.       |
| Integrated Corridor        | Coordinates freeway mainline, managed lanes,   |
| Management (ICM)           | parallel arterials, and transit via unified TMC|
| Traffic Incident           | Rapid detection, response dispatch, and clear- |
| Management (TIM)           | ance to prevent secondary collisions & delays. |
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Travel Time Reliability Performance Metrics

TSMO focuses heavily on travel time reliability rather than simple average speeds:

• 95th Percentile Travel Time: The travel time that $95%$ of trips experience (the "worst trip of the month").
• Planning Time Index (PTI): Ratio of the 95th percentile travel time to the free-flow travel time ($PTI = T_{95} / T_{FF}$). A $PTI = 1.60$ means a commuter must plan 48 minutes for a trip that takes 30 minutes in free-flow conditions.
• Buffer Time Index (BTI): Percentage of extra buffer time required above average travel time to arrive on-time $95%$ of the time ($BTI = [T_{95} - T_{mean}] / T_{mean}$).

2. FHWA TSMO Capability Maturity Model (CMM)

Developed through SHRP2 (Strategic Highway Research Program 2) and FHWA, the Capability Maturity Model (CMM) assesses an agency's institutional readiness to deliver effective TSMO programs across six core dimensions:

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|                         TSMO CMM SIX DIMENSIONS                             |
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| 1. Business Processes      | Formal planning, programming, and budgeting.   |
| 2. Systems & Technology    | Systems engineering, ITS architecture, Stds.   |
| 3. Performance Measurement | Outcome-based data collection and analytics.   |
| 4. Culture                 | Shared institutional value and agency vision.  |
| 5. Organization & Staffing | Dedicated TSMO job descriptions and training.  |
| 6. Collaboration           | Interagency coordination (MPO, DOT, Police).   |
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CMM Four Maturity Levels

3. National ITS Architecture (ARC-IT) & Industry Communication Standards

The Architecture Reference for Cooperative and Intelligent Transportation (ARC-IT Version 9.x) provides the standard framework for regional ITS planning across four views:

1. Enterprise View: Identifies stakeholders, organizational roles, and formal inter-agency agreements (Memoranda of Understanding [MOUs]).
2. Functional View: Defines functional processes and data flows connecting inputs to system outputs.
3. Physical View: Maps application objects to physical entities across four classes: Centers (TMC, Emergency Center), Field (Signals, DMS, Detectors), Vehicles (Transit, Connected Cars), and Travelers (Personal smartphones).
4. Communications View: Specifies layered communication protocol profiles.

Open Industry Standards (NTCIP & Connected Vehicle)

To prevent vendor lock-in and enable cross-jurisdictional interoperability, ITS deployments mandate open standards:

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|                      CORE ITS COMMUNICATION STANDARDS                       |
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| Standard                   | Scope & Object Definitions                     |
+----------------------------+------------------------------------------------+
| NTCIP 1202                 | Actuated Traffic Signal Controller (ASC) units |
| NTCIP 1203                 | Dynamic Message Signs (DMS / VMS)              |
| NTCIP 1204                 | Environmental Sensor Stations (ESS / RWIS)     |
| NTCIP 1209                 | Transportation Sensor Systems (TSS / Radar)    |
| NTCIP 1211                 | Signal Control and Prioritization (TSP / SCP)  |
| SAE J2735                  | Dedicated V2X Message Set Dictionary           |
|                            | (BSM, SPaT, MAP, SRM, SSM, TIM, RSA)           |
| SAE J2945                  | V2X On-Board System Performance Specifications |
| IEEE 1512                  | Family of Incident Management Message Sets     |
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Connected Vehicle Core Message Types (SAE J2735)

• BSM (Basic Safety Message): Broadcast by equipped vehicles 10 times per second ($10\text{ Hz}$) containing GPS position, speed, heading, acceleration, and brake status.
• SPaT (Signal Phase and Timing): Broadcast by signal controllers to convey current phase status and time remaining before change.
• MAP (MapData): Broadcasts 3D geometric intersection lane configurations, crosswalk paths, and speed limits to support autonomous positioning.

4. TMC Incident Management Timeline & Secondary Crash Prevention

Traffic incidents account for approximately 25% of all highway delays. The Traffic Incident Management (TIM) timeline tracks the lifecycle of an incident:

$\text{Incident Timeline: } T_0 \rightarrow T_1 \rightarrow T_2 \rightarrow T_3 \rightarrow T_4 \rightarrow T_5 \rightarrow T_6$

Where:

• $T_0$: Incident Occurrence (exact crash time).
• $T_1$: Detection (TMC identifies event via CCTV, probe data alarms, 911 calls).
• $T_2$: Verification (operator confirms lane blockages and severity).
• $T_3$: Response Dispatch (Safety Service Patrols [SSP], towing, police, fire, EMS).
• $T_4$: On-Scene Arrival (first responders establish temporary traffic control).
• $T_5$: Lane Clearance (all travel lanes reopened to traffic).
• $T_6$: Incident Clearance / Departure (all emergency vehicles leave scene; normal flow restored).

Secondary Crashes & Quick Clearance Laws

• Secondary Crash Risk: Research indicates the risk of a secondary collision increases by approximately 2.8% for each additional minute the primary incident obstructs traffic lanes.
• Safety Service Patrols (SSP): Roving motorist assist units provide fuel, tire changes, debris removal, and quick clearance pushing/pulling, delivering Benefit-Cost ($B/C$) ratios exceeding $15:1$.
• Quick Clearance Legislation: State "Move Over / Steer It & Clear It" laws mandate drivers move drivable vehicles involved in property-damage-only (PDO) crashes to shoulders or off-ramps immediately.