What the data for this category looks like
The data sources for this category mainly include official documents such as expressway operation management measures, toll policies, and maintenance specifications released by the Ministry of Transport and local transportation authorities, as well as internal operation guidelines and assessment rules of operating entities. The update rhythm adjusts according to policy release nodes, with no fixed cycle. Most documents use a chaptered text structure, containing fields such as document number, issuing authority, effective date, and clause content. They use specialized traffic operation units including kilometers, yuan/vehicle·trip, and hours.
What constraints these characteristics impose on knowledge base retrieval and recall
Metadata such as the effective date and document number of official documents is the core basis for user retrieval. Support for metadata field matching is required to avoid recalling expired or non-corresponding clauses. Retain clause context after chunking long documents, to prevent semantic fragmentation that reduces retrieval accuracy. Specialized traffic units and terminology text must be accurately embedded to avoid deviations in semantic vector generation. Configure an automatic sync trigger mechanism for non-fixed-update data sources, to ensure the timeliness of recalled content. Additionally, policy clauses are mostly independent entries, so avoid recalling irrelevant general traffic documents to improve matching precision.
How to Set Configurations
Reference only; verify against the target FastGPT release and deployment documentation.
| Configuration Item | Recommended Setting | Rationale |
|---|---|---|
| Similarity Threshold | 0.72–0.78 | Meets the precision requirement for matching policy clauses, avoids recalling irrelevant general traffic documents |
| Single Recall Limit | Top 8 entries | Expressway policy clauses are mostly independent entries; 8 entries can cover the policy basis needs of a single scenario |
| Search Mode | Hybrid Search | Matches both text semantics and metadata fields, enabling accurate location of policy documents with document numbers and effective dates |
| Rerank Switch | Enabled | Semantic drift may occur after chunking long documents; reranking corrects the sorting priority of recall results |
| Query Optimization | Enabled | Policy questions often contain specialized terminology; optimization improves the accuracy of semantic matching |
| Specified Knowledge Base Collection | Bind to the exclusive expressway operation policy collection | Isolate knowledge base data from other categories to avoid recalling irrelevant content |
Three Common Mistakes
- Phenomenon: Garbled text fragments appear in retrieval results after uploading expressway policy PDF or Word files. Cause: The file was not parsed with correct encoding, or contains non-standard special symbols such as road numbers and toll formats that are not adapted.
- Phenomenon: An unauthorized error is returned when calling the knowledge base API. Cause: A general authentication KEY was used, and the access permission for the corresponding expressway operation policy knowledge base was not bound.
- Phenomenon: Expired old version files are recalled when querying policy questions. Cause: Metadata retrieval filtering was not configured, and recall results were not filtered by effective date.
How to Confirm Configuration is Correct
- Upload a test expressway policy file, check that the parsed text has no garbled fragments, and confirm that encoding and special symbol adaptation works normally.
- Initiate a test query containing specialized terminology such as "provincial boundary toll station charging standards", check that the recall results include the corresponding clauses and the sorting meets expectations.
- View the binding configuration of the knowledge base collection, confirm that only the exclusive expressway operation policy dataset is associated, and no cross-category data is mixed in.
- Call the knowledge base API to initiate a test request, check that the authentication status of the returned results is normal, and no unauthorized error is reported.
The values provided are common starting points and should be evaluated against the reader's own samples.
Question material comes from public community discussions. Configuration values are common starting points and should be measured against your own samples. Verified on 2026-09-28.