David emailed a few questions regarding the trip generation spreadsheet I posted. He's a real estate broker trying to understand when his deals would trigger the need for a turn lane (footing the bill for a turn lane kills his development/lease deals because they aren't big enough to absorb the cost). Here's our conversation (his questions followed by my answers in bold):
- Based on the excel
file (8th Generation ITE Trip Generation), proposed use is a free
standing dollar store (Dollar General, Family Dollar), what is the recommended
ITE Code? 814 – Specialty Retail - Does the ITE Trip
Generation book help calculate left turn/right turn volumes? No.
You need to estimate a distribution pattern for the expected patrons.
This is what I get paid to do in my studies. Developers/brokers are actually in a good position to do this for retail developments (assuming they have a market study). Traffic engineers would typically charge $500 to $1,000 to prepare a small scale traffic study that would cover the driveway intersections. - Also, does the ITE trip calculation take into account size
of retail trade area and traffic counts? No, it's just an aggregate of data collected around the country. The spreadsheet provides average rates.
According to the Turner Fairbanks Research Lab, left turn lanes can cut the crash rate at an intersection by over 45%. How much concern does the average developer have for their customers’ safety?
PS: Thanks for the spreadsheet. It will be useful!