 |
| Six months into the road diet, collisions and injury collisions are up on Venice Blvd. |
One of the ongoing problems that plagues the Great Streets - Venice Blvd pilot project is a lack of project data. Our group submitted a California Public Records Act Request on August 8, 2018 specifically asking for the pre- and post-project data, including pedestrian, bicycle and traffic counts and accident data. We also asked for the criteria being used to evaluate this project - the metrics for success.
We are still waiting for a response.
We can all agree that having a complete data-set that we all can independently evaluate and discuss is essential to resolving the ongoing conflicts over this pilot project.
Until then, we are using what limited data we do have in the most prudent way possible.
Evaluating the Success of a Road Diet
Our community is full of very smart and intelligent people. One such person is Donna Speckman. She wrote an analysis of the LADOT mailers that were sent out in September 2017 making claims that the road diet was a success. You can read a reprint of what she posted on Nextdoor here.
She cited the Severin Martinez paper Who Wins When Streets Lose Lanes? and the Road Segment Rate Calculation on page 24 (page 35 of the PDF). Martinez says that using the Road Segment Rate Calculation formula is a way to compare accidents and injuries before and after a road diet. If the post-project number are lower than the pre-project numbers, this indicates that the road diet is a success.
This formula also appears on the Federal Highway Administration website, where they say:
The most appropriate use of this crash rate is to determine the relative safety of a roadway segment when compared to similar segment within a specific jurisdiction.
LADOT Data
Average Daily Traffic (ADT) Estimate
At the Great Streets website, the benchmarking report for Venice Blvd says that during a one day traffic study conducted on September 22, 2015, approximately 37,000 cars traveled on Venice Blvd between the intersections of Wasatch Ave. and Colonial Ave.
On the Venice Blvd Mar Vista website, LADOT posted a graphic showing the ADT had been reduced to 31,000 cars a day (posted below.)
Corridor Length
LADOT says the road diet is 0.8 miles long.
Collisions and Injury Collisions Data
Using the March 14th LADOT Open House “Raw Data” graphs:
Pre-road diet: May 20, 2016 to December 31, 2016
20 collisions
13 injury collisions
Post-road diet: May 20, 2017 to December 31, 2017
18 collisions
15 injury collisions
Road Segment Rate Calculation:
All Collisions
Pre-road diet: May 20, 2016 to December 31, 2016
(20 (accidents per 7.33 mos) x 1,000,000 miles traveled)/(37,000 cars/day x 225 days (in 7.33 months) x 0.8 miles) = 20,000,000/6,660,000 = 3.00 accidents per 1 million vehicle miles traveled
Post-road diet: May 20, 2017 to December 31, 2017
(18 (accidents per 7.33 mos) x 1,000,000 miles traveled)/(31,000 cars/day x 225 days (in 7.33 months) x 0.8 miles) = 18,000,000/5,580,000 = 3.22 accidents per 1 million vehicle miles traveled
Injury Collisions
Pre-road diet: May 2016 to December 31, 2016
(13 (injury accidents per ~7 mos) x 1,000,000 miles traveled)/(37,000 cars/day x 225 days (in 7.33 months) x 0.8 miles) = 13,000,000/6,660,000 = 1.95 injury accidents per 1 million vehicle miles traveled
Post-road diet: May 20, 2017 to December 31, 2017
(15 (injury accidents per 7.33 mos) x 1,000,000 miles traveled)/(31,000 cars/day x 225 days (in 7.33 months) x 0.8 miles) = 15,000,000/5,580,000 = 2.33 injury accidents per 1 million vehicle miles traveled
Supporting Documents
0 comments:
Post a Comment
We want to hear what you have to say. Leave a comment and share your feedback. Want to submit a story, picture or video for the blog? Use the Contact Us form to get in touch. Thanks!