Short answer: Up to 17 minutes of delay in our sample, if we compare the fastest estimated driving time (7 minutes) to the slowest (24 minutes) and assume congestion accounts for the whole difference

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We wanted to quantify the delays associated with traffic congestion in West Hollywood. The delays take time away from people traveling in cars and on buses. They also have an environmental impact due to increased vehicle emissions.

We decided to start with trips across West Hollywood, between Santa Monica & Doheny and Santa Monica & La Brea. It’s less than three miles from one point to the other. We gathered driving time estimates every half hour for 44 days, excluding Halloween. We assumed that driving times in excess of those in the early morning were caused by traffic congestion.


Driving across West Hollywood

In our sample, it took anywhere from 7 to 24 minutes to drive across the city. In other words, delays doubled or tripled the driving time compared to periods without traffic congestion. We know the driving time and delays can be even longer, but this report is based only on our limited sample.

Driving across the city often took 20 minutes or more during some part of the morning or evening commutes. It happened on 19 of the 32 weekdays in our sample: 11 morning commutes and 18 evening commutes. The chart below shows the driving times over our whole sample period. The blue peaks are the morning commutes. The orange peaks are the evening commutes.

Notes: (1) This chart shows the estimated time for the recommended route between the two points on Santa Monica Boulevard. In some cases, the recommended route avoided all or part of Santa Monica Boulevard. (2) We treat 4:00 AM as the beginning of each traffic day. That way, after-midnight-bar-closing traffic is grouped with the prior day. (3) We removed Halloween from the sample, because Santa Monica Boulevard was closed for most of it. Sources: Google; our analysis.


Times to avoid Santa Monica Boulevard

Sometimes it’s faster to avoid all or part of Santa Monica Boulevard, even for trips like these that start and end on Santa Monica. During our sample period, it usually happened during the weekday morning and evening commutes. It happened less often at lunchtime during the week and on Friday and Saturday nights. The chart below shows those avoid-Santa-Monica-Boulevard times as red triangles.

Note: We assumed that when Google recommended a longer route, it was to save time by avoiding all or part of Santa Monica Boulevard. Sources: Same as above.


Santa Monica Boulevard by time of day (weekday)

On weekdays, the westbound Santa Monica Boulevard driving time peaked during the morning commute. The average around 8:30 AM and 9:00 AM was 18 minutes to cross the city. The time dropped after that, but it stayed between 12 and 14 minutes until after 8:00 PM.

The eastbound driving time built up throughout the day. It peaked at 19 minutes around 5:30 PM and 6:00 PM. It declined after that, but didn’t drop below 12 minutes until 9:00 PM.

Note: To get Santa Monica Boulevard-specific numbers, we replaced any time estimates that avoided the Boulevard with simple estimates for a Boulevard-only route. Sources: Same as above.

The chart below converts the times into delay percentages for the most-delayed direction at each point in the day in our sample. It suggests that:

  • Average weekday delays ranged up to 150%
  • The evening peak took up a big part of the day, starting at 3:00 or 3:30 PM and running through 8:00 PM
  • Delays weren’t confined to the peaks: many off-peak hours have delays of 50% to 100%
Note: We calculated delay by comparing the average driving time in each period to the time during the quickest period of the average weekday (early in the morning). Sources: Same as above.


Santa Monica Boulevard by time of day (weekend)

Crossing the city on a Saturday, the peak driving time of 15 minutes was in the afternoon, between 2:30 PM and 4:00 PM. Traffic delays built up throughout the morning, then held steady for the afternoon and early evening. They dipped briefly, before rising again before midnight. Eastbound and westbound delays were similar throughout the day, so the traffic volumes may also have been similar.

Sources: Same as above.

On the average Sunday, the peak cross-city driving time was a bit lower, 14 minutes. It stayed in the 12- to 14-minute range throughout the afternoon. Driving times were almost the same for eastbound and westbound trips.

Sources: Same as above.


Santa Monica Boulevard by day of week

We wondered which day was the worst for driving across West Hollywood on Santa Monica Boulevard. Based on our sample, it was Wednesday overall, but it depended on the time of day:

  • Morning commute: Tuesday, with Wednesday and Thursday as runners-up
  • Lunchtime: Wednesday and Friday are tied, followed by Tuesday
  • Evening commute: Wednesday, closely followed by Tuesday and Thursday
  • Nighttime: Saturday, then Friday, with Thursday farther behind

The mountainous chart below illustrates the estimated/sample driving times by day of week and time of day. Time of day runs from left to right. We start the traffic day at 4:00 AM. The day of week runs from front to back, starting with Sunday in the front. The height is the number of driving minutes. The heights are also color-coded, with yellow for 10 to 15 minutes, orange for 15 to 20 minutes, and red for more than 20 minutes.

Note: Shows the driving time for whichever direction is slower during that part of the day. Sources: Same as above.

Looking from left to right, we see the early-morning quiet (gray) followed by the morning peak (yellow and orange). That peak isn’t as tall or as long as the evening peak. In the middle of the day, we see elevated (yellow) travel times with even higher (orange) lunchtime delays a couple of days a week.

The evening peak starts rising up around 3:00 or 3:30 PM. It’s long. It’s also higher than the morning peak, reaching above 20 minutes (red) on at least one day in the average week. To the right, we see the quiet nighttime traffic (gray) in the early part of the week and the nighttime mini-peak (yellow) on Thursday, Friday, and Saturday.

Revised to make clear that the report is based on estimates from a limited sample.


http://wehobythenumbers.com/wp-content/uploads/2017/12/201712-traffic-smb-3d.jpghttp://wehobythenumbers.com/wp-content/uploads/2017/12/201712-traffic-smb-3d-300x300.jpgDavid WarrenPerformance (effectiveness)Transportationdriving,streets,traffic
Short answer: Up to 17 minutes of delay in our sample, if we compare the fastest estimated driving time (7 minutes) to the slowest (24 minutes) and assume congestion accounts for the whole difference| We wanted to quantify the delays associated with traffic congestion in West Hollywood. The delays...