The implementation of tolls on Highway 99 has coincided with decreases in roadway performance on Interstate 5 and on downtown Seattle streets. The degree of impact varies significantly depending upon the time of day and direction of travel. INRIX Research analyzed speed performance by hour for the week preceding the adoption of tolls, and the first week of tolling (excluding Monday, Veteran’s Day).

Interstate 5 northbound underwent major declines in performance with peak conditions starting at 6:00 AM, approximately one hour earlier than before the tolling began. Surprisingly, congestion cleared for both periods of observation by 11 AM, despite congestion being much worse for a longer period of time. Travel speeds declined the most – by 9 MPH – during the 8:00-9:00 AM commute period.

Corridor Name Metrics 5:00 AM 6:00 AM 7:00 AM 8:00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM
I5 North (Before) MPH 57 43 36 31 31 34 45 56 56 53 45 38 24 26 53
I5 North (After) MPH 51 37 32 22 27 28 39 55 54 52 42 32 24 27 50
Change MPH -6 -6 -4 -9 -4 -5 -6 -1 -1 -1 -3 -7 0 1 -3

The change experienced by Interstate 5 southbound varied significantly from northbound. Congestion did not set in earlier, nor was it as severe at peak commute hours. Instead, the period of congestion elongated until the morning and the afternoon commute periods merged. For the week following the implementation of the tolls, I-5 south experienced heavy traffic before 7:00 AM to nearly 8:00 PM. However, it bears noting speeds did not drop below 30 MPH on average, significantly higher than the low of 22 MPH experienced on I-5 north. Buy Levitra http://www.healthfirstpharmacy.net/levitra.html

Corridor Name Metrics 5:00 AM 6:00 AM 7:00 AM 8:00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM
I5 South (Before) MPH 64 55 43 38 40 54 53 44 43 32 27 29 31 37 50
I5 South (After) MPH 62 55 40 40 44 39 40 44 38 34 30 29 33 35 44
Change MPH -2 1 -3 2 4 -15 -14 0 -5 2 3 0 2 -2 -6

Downtown road performance decreases proceeded largely as expected with both a worsening and elongation of congestion periods. Unlike the analysis of I-5, speed data was collected from numerous facilities, contributing to a smoother depiction of travel time changes. Overall changes were far more moderate in downtown due to the opening of the tunnel than I-5. It is likely attributable to the fact tunnel users displaced by the toll can more easily reach their destinations via I-5 than through Seattle’s surface streets. Viagra 100 mg http://www.wolfesimonmedicalassociates.com/viagra/

Corridor Name Metrics 5:00 AM 6:00 AM 7:00 AM 8:00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM
Downtown (Before) MPH 12 11 10 10 10 10 11 10 11 10 10 10 9 10 11
Downtown (After) MPH 12 11 10 9 9 10 10 10 10 10 10 9 9 10 11
Change MPH 0 0 0 -1 -1 -1 -1 0 0 0 0 0 -1 0 0

 

As commuters continue to adapt to the tolling regime and weigh the cost versus time savings, it is likely a new equilibrium will be reached that more closely resembles pre-tolling performance. Given the relatively low rates, and large time penalty of avoidance it is unlikely the very high number of displaced trips continues. Long-term tolling may improve overall network performance by enabling Highway 99 to operate in a more efficient state.