Empty Chassis Repositioning & Split Mileage: Drayage TMS Systems
Strong Tower Consulting designs and implements dynamic rating engines that automatically isolate bobtail split legs, calculate out-of-route repositioning mileage, and generate ocean carrier compensation vouchers for intermodal drayage operations. Founded in Minnesota in 2008, we have spent more than 18 years solving complex transportation technology challenges for motor carriers and logistics providers.
The Real-World Drayage Cost Leak
Ocean carriers frequently direct drayage drivers to retrieve chassis from off-dock private depots located 15-40 miles from the marine terminal. The carrier is paid only for the loaded move, yet the driver incurs significant unpaid bobtail and empty repositioning miles. Without precise capture and automated billing, these miles erode margin and create persistent disputes with steamship lines.
Strong Tower's intermodal drayage TMS architecture closes this gap by treating each chassis split as a distinct, auditable event with its own mileage calculation and revenue recovery workflow.
Core Systems Architecture
The solution is built around a central mileage solver service that sits between the dispatch board, the driver mobile application, and the rating and billing engine. Key components include:
- Event-driven equipment state machine (Chassis Pickup, Gate In, Gate Out, Empty Return)
- Real-time route engine using PC*MILER or Google Maps Distance Matrix API
- Configurable ocean-carrier business rules table
- Automated voucher and 214 status generation
- Persistent leg segmentation stored in a normalized relational model
Driver App Event → TMS Event Bus → Mileage Solver Service
↓
PC*MILER / Google Maps API (practical route miles)
↓
Compare against baseline route → Calculate delta miles
↓
Apply carrier-specific rate matrix → Generate voucher line
↓
Transmit via EDI 214 or API to ocean carrier / broker
Data Mapping: Split Leg Model
| Field | Description | Source |
|---|---|---|
| leg_id | Unique identifier for each segment | System generated |
| parent_load_id | Reference to original drayage order | TMS order header |
| leg_type | bobtail | reposition_empty | linehaul | return_empty | Event rules engine |
| start_latlon | GPS coordinate of leg start | ELD or driver app |
| end_latlon | GPS coordinate of leg end | ELD or driver app |
| calculated_miles | Practical miles from routing engine | PC*MILER / Google Maps |
| billable_miles | Miles eligible for ocean carrier compensation | Business rule application |
| ocean_carrier_code | SCAC or assigned code | Order or equipment record |
| voucher_status | pending | approved | invoiced | paid | Workflow engine |
Automated Workflow Sequence
- Driver arrives at off-dock depot and scans or logs chassis pickup via mobile application.
- TMS records GPS waypoint and creates initial bobtail leg.
- Upon departure, the mileage solver calculates practical route distance to marine terminal gate.
- System compares calculated distance against the baseline terminal-to-destination route stored on the order.
- Incremental repositioning miles are isolated and tagged with the responsible ocean carrier.
- When the loaded move is completed, the TMS automatically generates a secondary voucher or accessorial line item.
- Voucher is transmitted to the ocean carrier or freight broker via EDI or API.
- Revenue is allocated back to the driver pay and carrier P&L in real time.
Strategic Integrations
Strong Tower specializes in tight integration between drayage TMS platforms and the systems that feed them. This architecture connects directly to:
- ELD providers for verifiable GPS and duty status
- Ocean carrier APIs and EDI 315/214 loops for status and equipment control
- PC*MILER or Google Maps for authoritative mileage
- Accounting and settlement platforms for automated voucher posting
Our ELD-EDI Integration practice ensures that every chassis event is captured with forensic accuracy while maintaining compliance with FMCSA electronic logging rules.
Carrier Rate Matrix Optimization
The mileage solver becomes exponentially more powerful when paired with a comprehensive carrier rate matrix optimization model. Ocean carrier agreements, port-specific accessorial tables, and fuel surcharge logic are maintained in a single configurable repository. This allows the system to apply the correct repositioning rate per steamship line without manual intervention.
For carriers that also operate as brokers, the same engine supports brokerage and 3PL margin management, ensuring that customer accessorials are billed at the correct markup while vendor costs are captured at the true repositioning mileage.
Broader Application Across Fleet Types
While the architecture was developed for intermodal drayage, the same split-leg and mileage solver logic has been successfully deployed for specialized and heavy-haul carriers that manage complex equipment repositioning. The underlying TMS implementation patterns are documented in our TMS Implementation practice area.
Frequently Asked Questions
How do you automatically identify and isolate chassis split legs in an intermodal drayage TMS?
By capturing distinct GPS waypoints and equipment events at the off-dock chassis depot, marine terminal gate, and final load or unload location. The mileage solver engine then segments the move into paid linehaul, bobtail, and non-revenue repositioning legs using business rules configured per ocean carrier.
Can a drayage TMS automatically calculate out-of-route mileage for empty chassis repositioning?
Yes. Strong Tower designs rating engines that call PC*MILER or Google Maps APIs in real time to compute practical route miles between the chassis pickup location and the marine terminal, then subtracts the baseline route to isolate incremental repositioning miles that can be billed to the ocean carrier or steamship line.
How does the system generate secondary billing vouchers for ocean carrier chassis compensation?
Once the split leg and repositioning mileage are validated, the TMS automatically creates a voucher or accessorial line item linked to the original load. The voucher references the ocean carrier agreement, includes the calculated miles, and transmits via EDI 214 or API to the responsible billing party.
What integration points are required between a drayage TMS and ocean carrier systems for chassis management?
Key integrations include 315 status messages for equipment events, API calls for chassis pool availability, and automated transmission of demurrage and chassis usage reports. Strong Tower specializes in ELD-EDI integration that synchronizes driver tablets, TMS dispatch, and ocean carrier portals.
Does this architecture work for both asset-based motor carriers and intermodal freight brokers?
Yes. The mileage solver and split-leg logic are carrier-agnostic. Asset carriers use it for internal cost allocation and revenue recovery; brokers and 3PLs use it to enforce accurate accessorial billing to shippers and ocean carriers while maintaining margin visibility.
Optimize Your Intermodal Drayage Operations
Stop absorbing hundreds of unpaid repositioning miles per week. Let Strong Tower Consulting design and implement a purpose-built mileage solver and chassis split engine tailored to your fleet, your ocean carrier agreements, and your existing TMS or brokerage platform.
Call us today at 763-244-1373 or schedule a technical assessment.
Request Intermodal TMS AssessmentStrong Tower Consulting, LLC - Transportation Systems Architecture since 2008. Exspeedite is a sister company under common ownership (separate EINs; liability firewall).