Figure 34: Hourly Volume Percentage Changes – PennDOT

Figure 34. Google travel times that correspond to each diurnal time window were aggregated for all routes.

Figure 34: Hourly Volume Percentage Changes – PennDOT

Explanation for derivation of the delay coefficients (based on Google data) is given in Table 9 below. Xs represent sums of averaged travel times for the relevant times of the day window when the work-zone segment of the 7th Street is closed. Coefficients for PM peak hour are considered to be equal to 1.00. The rest of the delay adjustment coefficients are calculated by applying relevant derived delay adjustment factors to the results from the VISSIM’s model. Time of day windows and volume adjustment factors are based on Figure 34 and similarity of traffic conditions for the observed hours. Volume adjustment factors serve to reduce delay for all vehicle categories in free flow hours and other off-peak hours (when traffic volumes are lower). It should be mentioned that since buses do not operate from midnight until 5 AM the use of a reduction factor for that time window (for buses) is necessary. An important part of the methodology is simulating expansion factors which are used to derive delay for proposed time windows based on the delay from simulation.

Delay caused only by work zone impact is calculated as:

where: (34)