Primary Carrier / Backup Carrier

In a routing guide, the primary carrier is the first carrier tendered on a given lane – they've won the business through an RFP or negotiation and are expected to accept and haul the majority of loads on that lane at the contracted rate. Backup carriers are the next in line, activated when the primary rejects a tender or is otherwise unavailable. Most routing guides include two to three backups per lane.

The primary-backup structure exists to balance cost and reliability. The primary carrier typically offers the best negotiated rate for the lane and has committed to a certain acceptance level. Backup carriers are priced slightly higher but provide a safety net. The final fallback – if all routing guide carriers reject – is the spot market, where rates are unpredictable and often significantly more expensive.

Effective routing guide management means monitoring whether the primary carrier is actually performing to their commitment. If a primary carrier's acceptance rate drops below 85%, the shipper is leaking volume to more expensive backup carriers and spot market loads. This data drives quarterly business reviews and contract renegotiations – either the carrier recommits, the rate adjusts, or the carrier's position in the guide changes.

The routing guide is only as good as its maintenance. Shippers who set up a routing guide during annual RFPs and never revisit it will find that market conditions, carrier capacity, and lane dynamics shift the guide out of alignment within months. Regular performance reviews and guide updates keep primary and backup carrier assignments reflecting current reality.