Oregon Commute Trip Reduction Estimator Tool

This tool helps Oregon employers and partners estimate the potential reduction in drive-alone commute trips from implementing various transportation demand management (TDM) strategies.

For employers subject to the Oregon Department of Environmental Quality (DEQ) ECO Program rules, the estimated results from this tool can be included as part of the commute trip reduction plan you submit to DEQ.

Use your print screen function, in-browser print-function, or snipping tool to save your results. A “Download PDF” option will be coming in a future version of the calculator.

The tool is designed to reflect typical effectiveness levels for urban and suburban settings, where infrastructure and transportation options exist. Results in rural areas can vary widely and are not reliably supported by existing research.

While individual outcomes may vary, the estimates are grounded in CAPCOA guidance and other peer-reviewed sources. They are designed to provide directional insights, not precise forecasts.

This tool models a single snapshot of selected strategies. For phased implementation, try running multiple versions of the tool using different selections.

Choose all that apply. The tool is designed with built-in dampening to prevent inflated estimates from overlapping strategies.

This prevents inflated outcomes. Research shows diminishing returns as more strategies are layered—especially when they target the same group of employees.

In real-world conditions, no combination of strategies has been shown to reduce vehicle commute trips by more than 60% across a broad employee base. The global cap reflects maximum plausible behavior change, even under ideal conditions.

No. Any information you enter will not be saved or stored after you close or leave the tool.

Use your print screen function, in-browser print-function, or snipping tool to save your results. A “Download PDF” option will be coming in a future version of the calculator.

Methodology for Combining Strategies Across Categories

To estimate the impact of multiple transportation demand management (TDM) strategies implemented at a worksite, we followed the methodology outlined in the California Air Pollution Control Officers Association (CAPCOA) guidelines. Recognizing that emissions reductions from different strategies are not necessarily additive, we applied a linear dampening approach to combine strategies within each category and across categories.

Step 1: Combining Strategies Within Each Category

The following categories were analyzed separately:

• Worksite Amenities
• Information and Promotion
• Employee Commute Support Programs
• Employee Benefits
• Incentives
• Parking Strategies

For each category, we identified relevant strategies and their estimated trip reduction impacts as provided in CAPCOA. To account for diminishing returns when multiple strategies are implemented within a single category, we multiplied their effectiveness rates together rather than summing them. This approach ensures that the combined impact does not unrealistically overestimate reductions, reflecting CAPCOA’s guidance that emissions reductions are not strictly additive.

Mathematically, if a category includes three strategies with effectiveness values of r1, r2, and r3​, the combined reduction within the category is calculated as:

R_category = 1− (1−r1) × (1−r2 )× (1−r3)

This formula ensures that each additional strategy has a diminishing marginal impact, preventing overestimation.

Step 2: Combining Across Categories for Commute Reduction Programs

Once reductions were calculated for each category separately, we applied the same linear dampening approach across five of the categories associated with Commute Trip Reductions by multiplying the reductions:

Rcommute reduction programs = 1 − (1 − RWorksiteAmenities) × (1 − RInformationandPromotion) × (1 − REmployeeBenefits) × (1 − RIncentives) × (1 − REmployeeCommuteSupportPrograms​)

Step 3: Applying Maximum Reduction Limits by CAPCOA Subsector

“To ensure the final estimated trip reduction remains within realistic and empirically supported bounds, we applied maximum reduction caps based on CAPCOA guidance for two relevant subsectors:

1. Commute Reduction Programs Maximum (45%)
The cumulative reduction from strategies categorized under Worksite Amenities, Information and Promotion, Employee Commute Support Programs, Employee Benefits, and Incentives was calculated in Step 2.

Per CAPCOA’s guidance, this set of strategies falls within the “”Trip Reduction Programs”” subsector, which has a maximum allowable reduction of 45%. If the calculated reduction exceeded 45%, it was capped at this threshold.

2. Parking Strategies Maximum (35%)
Parking-related strategies were analyzed separately, aligned with CAPCOA’s “”Parking or Road Pricing/Management”” subsector. According to CAPCOA, the maximum trip reduction from parking strategies should not exceed 35%.
If the cumulative impact of all parking-related strategies exceeded 35%, it was capped at this limit.”

Step 4: Calculating the Final Trip Reduction with a Global Maximum

In the final step, we combined the Commute Reduction Programs total and the Parking Strategies total while ensuring that reductions remained within practical bounds. The final trip reduction was determined using the following approach:

1. Applying Category-Specific Maximums:

The total reduction from Commute Reduction Programs (Step 2) was constrained to a maximum of 45%, as described in Step 3.
The total reduction from Parking Strategies was capped at 35%, per CAPCOA’s “Parking or Road Pricing/Management” subsector.

2. Multiplying the Two Subsector Totals:
To estimate the cumulative effect of both strategy categories while accounting for diminishing returns, we multiplied the adjusted totals:
Rfinal = (1 − min(R_{commute Reduction Programs}, 45%))× (1 − min(R_Parking, 35%))
This ensures that each subsector’s reduction is included while maintaining a realistic combined effect.

3. Imposing the Global Maximum Reduction (60%)
Based on CAPCOA’s methodology and empirical trip reduction estimates, a global maximum reduction of 60% was established.
If the calculated total exceeded 60%, it was capped at this threshold:
R_Final = min (RFinal, 60%)

This final step ensures that reductions remain realistic, consistent with CAPCOA guidance, and account for compounding effects without overestimating the impact of multiple strategies.

See the full assumptions here.