Public Roads: A Journal of Highway Research and Development, Vol. 41 No. 1
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Summary
This paper evaluates the Community Aggregate Planning Model (CAPM), a sketch planning tool designed to rapidly compare the economic, social, environmental, and performance characteristics of alternative urban transportation plans. Developed by the Federal Highway Administration (FHWA) and the Urban Mass Transportation Administration, CAPM addresses the need for a low-cost, efficient method to screen multiple alternatives before committing to time-intensive meso- or micro-level modeling. The model operates by aggregating data into communities of 8 to 30 square miles, requiring minimal input such as vehicle trip ends, lane miles, and freeway connectivity, while avoiding the need for extensive network coding or calibration. The study details a demonstration project conducted in three diverse urban areas: Phoenix, Arizona; St. Louis, Missouri; and Cincinnati, Ohio. In Phoenix, CAPM was used to evaluate four Interstate 10 alignment alternatives. The model successfully replicated existing conditions, with regional vehicle miles of travel (VMT) estimates within acceptable limits of ground counts. It identified the "Durango" alternative as the most cost-effective option with lower vehicle operating costs and fuel consumption. Sensitivity analyses in Phoenix also demonstrated that reducing average work trip times significantly decreased regional VMT, validating the model’s responsiveness to policy variables. In St. Louis, the model faced challenges due to the region’s fragmented freeway system and natural barriers like the Mississippi River. While regional VMT totals were accurate, community-level distributions showed discrepancies, particularly where freeway discontinuities existed. Updating the base year to a more continuous 1970 system improved performance. Cincinnati results were similarly mixed; while regional totals matched ground counts, individual segment volumes differed by up to 50% because regional through-traffic was initially excluded from outputs. Additional applications in Indianapolis and Tampa-St. Petersburg confirmed that CAPM could effectively narrow down alternatives for detailed study, with Tampa users noting strong agreement between model outputs and observed values after minor modifications. The paper concludes that CAPM is a valuable "first cut" tool for transportation planning, offering a quicker alternative to conventional highway assignment models. It provides decision-makers with easily understood evaluation criteria, including accident rates, pollution emissions, and construction costs. However, the authors note drawbacks, including significant effort required for initial data preparation and difficulties in duplicating ground counts in regions with discontinuous networks or complex geography. Despite these limitations, CAPM extends the range of existing planning procedures by enabling the efficient comparison of numerous alternatives, thereby supporting more informed early-stage decision-making.
Key finding
CAPM regional vehicle miles of travel estimates agreed well with observed ground counts and conventional assignments, although community-level estimates showed discrepancies in areas with fragmented freeway systems or bordering cordon boundaries.
Methodology
mixed_methods
Provenance
The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | rosap | — | — | 2 | 2026-05-23 |
| archive | success | — | — | — | 1 | 2026-05-23 |
| extract | success | cached | — | — | 2 | 2026-06-10 |
| clean | success | — | — | — | 1 | 2026-06-01 |
| chunk | success | — | — | — | 1 | 2026-06-01 |
| embed | success | — | — | — | 1 | 2026-06-02 |
| enrich | success | — | — | — | 1 | 2026-05-23 |
| promote | success | — | — | — | 1 | 2026-05-23 |
| summarize | success | llm | qwen3.6-27b-prismaquant | summ-v5 | 3 | 2026-06-10 |
| tag | success | vector_similarity | — | — | 19 | 2026-06-11 |
| verify | success | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
Topics
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- signage environment
- rail grade crossings
- perceptual countermeasures
- roadway lighting effects
- emergency work zone conspicuity
Information type
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- Applied Guidance: countermeasure evaluation
- Empirical Findings: observational prevalence
- Methodological Resource: dataset resource