GreenTRIP Connect FAQ


  1. Q: When adding in affordable units to a building, does Connect assume a distribution of affordable units across all unit sizes in proportion to the number of units for each type? 
    A: Yes, Connect assumes that affordable units are distributed evenly across the unit mix.
  2. Q: Is it possible to keep project inputs and change the parcel?
    A:  Yes, once you have completed the project inputs, click on “clear parcel” and select a new parcel. All of your original inputs will remain. The only exception is changing a parcel from the Bay Area to outside of the Bay Area - your custom parking will revert to zero.

    If you want to update the average mix of units, sizes, and rents to reflect the new location, select “Restore Defaults” (in the “Building” area of the tool). To learn how PUMS data is used to calculate these values, refer to our Methodology page.
  3. Q: What is the VMT reduction based on unbundled parking and limited parking supply?
    A: Connect follows the CAPCOA Guidelines and caps VMT reduction at 20% for combined parking reduction strategies. More information can be found in the CAPCOA Quantification Report (2010) p. 55, 61-62, and in our TDM Methodology paper.
  4. Q: How are the “Resident savings from selected GreenTRIP strategies” (on the dashboard) calculated?
    A: This is the total value of the strategies you selected for your project: (1) resident transit passes, (2) car sharing memberships, and (3) bike sharing memberships. If the resident gets a transit pass (value of approximately $75/month), a car share membership (value of $60/year) and a bike share membership (value of $88/year), that adds up to a combined value of $1048/year. 
  5. Q: What is the predicted parking use for a location and does it vary by location?
    A: Connect predicts parking at a location for the Bay Area only, called the “low impact parking estimate,” based on the GreenTRIP Parking Database. For more information on the variables that go into this model, read the Parking Model Methodology paper. The prediction relies on data from the building and the location, including transit access. We used the lower end of the ITE (Institute of Transportation Engineers) standard for low-rise and mid-rise apartments for parking use as a baseline: 1.2 spaces/unit. Connect shows how much space and money can be saved with reduced parking below the 1.2 ratio. This is in contrast to the often-found municipal parking requirement of 2.2 spaces/unit. If you would like to, the user can change the municipal parking requirement to what is found in your town. That input is located at the bottom of the inputs on the left hand side. The City of LA is collecting parking database that could add parking prediction for that city in the future.
  6. Q: Why is there “n/a” under Parking Spaces predicted use for my location?
    A: The parking model for Connect only works in the Bay Area right now. It is based on the GreenTRIP Parking Database, which only included data collected in the Bay Area. We are hoping to have a Los Angeles Area Parking Database with similar data the city has collected. We do not anticipate a statewide parking model at this time, but are looking into it.
  7. Q: How does Draw to Select work?
    A: This feature allows you to outline a larger area and select all parcels within the border you draw. It is a quick way to include an entire city block.
  8. Q: On the Dashboard, the Comparison snapshot shows “per unit” and “building totals” buttons, as well as “per day” and “per year.” What do they do?
    A: By changing the Comparison snapshot, you can see all of the outputs at the unit level, or aggregated to the building level. Also, you can change the time reference to be adjusted to the unit that matters more to you.
  9. Q: What do the percentages at the bottom of the Dashboard mean?
    A: For parking, driving and greenhouse gas emissions, the percent shows a reduction when compared with the “average location” for that area (top row of outputs in the Dashboard), which is either County (be default), City or Region, if available.
  10. Q: What data is pulled from county level, from census tract level and from metro area level?
    A: All “average location” data for VMT and GHG emissions  is pulled from the county level. Building size is also based on a county average. Mix of unit size by bedroom and average rent data is based on PUMS (Public Use Microdata Sample) data.
  11. Q: Does adding carshare memberships reduce VMT according to how many carshare pods are located nearby? 
    A: The reduction in VMT for carshare and the other GreenTRIP Strategies is uniform in all locations across the state. It is up to the user to check if carshare and transit passes are available for that location before using those strategies.Carshare pod locations are in green on the map. For more on the methodology behind the GreenTRIP strategies see the TDM Methodology paper.
  12. Q: Why does the “Total Units” field auto-fill?
    A: Once you pick a parcel, Connect uses that parcel's county data to auto-fill the "average" building size in that county by unit count. This is also how the building defaults are auto-filled in the "Customize Units" fields. Mix of unit sizes by bedroom and average rents are based on PUMS data for the county.

  13. Q: What does “if built in an average location” mean?
    A: In the top row of the dashboard, Connect generates the estimated driving, greenhouse gas emissions, and predicted parking use for your project if it were located in “the average place” in the county, city, or region, using your inputs (or county defaults) for number of units, bedrooms, and rents.

    You can select city, county, or region to change the “average” location to which your project is compared. Turn on relevant map layers to see the boundary of the “average” location selected. County defaults for number of units, bedrooms, and rents will not change unless you customize them.

    Driving, greenhouse gas emissions and predicted parking use are modeled assuming the building has a fixed default of 1.2 parking spaces/unit for the parking supply.
  14. Q: What does “if built on selected parcel” mean?
    A: In the second row of the dashboard, Connect generates the estimated driving, greenhouse gas emissions, and predicted parking use for your project if located on the parcel(s) you selected on the map, using your inputs (or county defaults) for number of units, bedrooms, and rents.

    The parking supply is either your parking input or the default “low impact parking estimate.” These outputs include no affordable housing units in the building and no GreenTRIP strategies implemented.

    If affordable housing is included, it will be accounted for in the next row, titled “with affordable housing.”

    Finally, if GreenTRIP strategies are included, they will be accounted for in the bottom row, titled “with GreenTRIP Strategies.”
  15. Q: Why does Connect say “Parcel Not Available: There is no parcel data available at this location. Please select another parcel?”
    A: There are counties in CA where no parcel data was available for our parcel data set. These include: Colusa County, Inyo County, Lassen County, Mariposa County, Modoc County, Plumas County, San Luis Obispo County, and Siskiyou County.