How much time does traffic congestion add to a drive across West Hollywood?

|

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

During our sample period, it took anywhere from 7 to 24 minutes to drive across the city. In other words, delays can double or triple the driving time compared to periods without traffic congestion.

Driving across the city can take 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.

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.

Santa Monica Boulevard by time of day (weekday)

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

The eastbound driving time builds throughout the day. It peaks at 19 minutes around 5:30 PM and 6:00 PM. It declines after that, but doesn’t drop below 12 minutes until 9:00 PM.

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

• Average weekday delays range up to 150%
• The evening peak takes up a big part of the day, starting at 3:00 or 3:30 PM and running through 8:00 PM
• Delays aren’t confined to the peaks: many off-peak hours have delays of 50% to 100%

Santa Monica Boulevard by time of day (weekend)

Crossing the city on a Saturday, the peak driving time of 15 minutes is in the afternoon, between 2:30 PM and 4:00 PM. Traffic delays build throughout the morning, then hold steady for the afternoon and early evening. They dip briefly, before rising again before midnight. Eastbound and westbound delays are similar throughout the day, so the traffic volumes may also be similar.

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

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 may be Wednesday overall, but it depends 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 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.

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.