For this analysis, data was obtained from workers on work journey start times and return times for a five-day period. Based on this data, the morning home-to-work trip start times and evening work-to-home trip start times (see figure 5.10) as well as the actual commuting times for each leg of the trips were derived.
Figure 5.10: Start times for (a) Morning home-to-work trips and (b) Evening work-to-home trip Source: Based on Field Survey, February 2015
The analysis show that a significant proportion of morning home-to-work travel (80%) occur between the early hours of 6:00am and 9:00am (figure 5.10a)22. Whereas, nearly half of all work trips start times within this period took place in the early morning off-peak period between 6:00 am and 7:00 am, 44% of them were taken during the early morning peak hours of commuting, between 7 and 9 am. The remaining seven percent of morning work trips occurred during the off-peak periods after 9am. In the case of return journeys (figure 5.9b), whereas about 23% of trips were taken during the off-peak hours before 4:30pm, about 40% of evening work-to-home trips occurred during the peak hours between 4:30pm and 6:30pm. The remaining 37% of journeys occurred during the evening off-peak hours after 6:30pm.
Furthermore, the analysis revealed a positive association between morning work commute start times and whether the goal was to escape traffic congestion or not (Pearson X2 = 35. 331, df = 6, p < 0.00, Cramer’s V = 0.20) and that of return work trip times in the evening (Pearson X2 = 26. 241, df = 8, p < 0.00, Cramer’s V = 0.14)23. Overall, about 49% of the respondents, who commuted to work using motorized transportation (i.e. public and private transport) indicated that they chose the times they went to work in the mornings to avoid traffic congestion. Among morning off-peak commuters 54% and 22% of journeys starting between 7 and 9am and after 9am respectively, were taken by commuters with the with the goal to escape traffic congestion. In the case of return journeys in the evening, 28% of all commuters indicated that they chose their traveling times with the goal to escape traffic congestion. Within this group of commuters, 29% and 30% of trips that occurred during evening off-peak periods before 4:30pm and after 6:30pm respectively, were taken with the goal of avoiding traffic congestion.
Thus, most of the morning peak-hour commuters (54%) and evening peak-hour commuters (74%), did not choose their travelling times to avoid congestion. Instead, their travel times in the mornings were scheduled with the goal to arrive at the work-place at stipulated reporting times while evening travel times started after stipulated work closing times. Return work journeys were therefore consistent with formal rules regarding work reporting and closing hours, which act as a form of authority constraint on travel times. The observed peak-hour
22 Work commute start times were found to be consistent among the respondents. Consequently, Individuals
who commuted at certain times of the day three or more times during the five-day period, were assigned that time as their regular work trip start times in the mornings and in the afternoon.
23 Work travel times were divided into three categories namely; off-peak, peak, and off-peak hours for both
travel, characterized by congestion is therefore a consequence of constraints imposed by these formal rules rather than the result of the personal choices of individual commuters regarding when they decide to travel.
Summary descriptive statistics of data on actual times spent traveling to and from work are presented in table 5.9. The analysis show morning and evening work travel times for all trips, trips associated with home-based work only and trips associated with non-home-based work only.
Table 5.9: Travel times for morning work trips
Travel time (Minutes)
All single work trips (%)
Home-based work trips only (%) Non-home-based work trips only (%) Home-work (mornings) Work-home (Evenings) Home-work (mornings) Work-home (Evenings) Home-work (mornings) Work-home (Evenings) below 10 minutes 19 11 58 40 6 2 10 to 19 21 5 27 14 18 2 20 to 29 17 2 9 4 19 1.5 30 to 39 18 67 2 36 24 77 40 to 49 12 1 1 0 16 1 50 to 59 4 1 2 0 5 1.5 60+ 10 12 0 6 13 5 Average 25.0 32.85 5.0 10 30.0 32.86 SD 19.79 18.61 10.89 19.37 19.01 16.131 Maximum 120 105 60 105 120 105
Source: Based on Field Survey, February 2015
On the average, commuters spent 25 minutes and 33 minutes travelling from home-to-work in the mornings and returning to home from work in the evenings respectively. For home-based work (work located within the immediate vicinity of the dwelling) where trips were completed by walking, the average walking time to work was 5 minutes and 10 minutes in the mornings and evenings respectively. The exact reasons for the difference in walking times in the morning and evening could not be inferred directly from the survey. Notwithstanding, it is possible that individuals might take relatively longer routes where perhaps there might be others using it or there might be good lighting in evening for safety reasons. In the case of trips associated with non-home based work, the average travel times was 30 minutes and 33 minutes in the mornings and evenings respectively.
Aggregating the travel times for return trips associated with home-based work and non-home- based work, individuals spent on the average an hour (SD = 32.32, maximum = 180 minutes) travelling to and from work daily. In the case of trips associated with home-based work only, individuals spent about 27 minutes (SD = 25.053, maximum = 120 minutes) daily travelling to
and from work while non-home-based workers spent a little above an hour (62 minutes) doing same (SD = 27.30, maximum = 180 minutes).
Spearman’s Rho correlation analysis shown a positive association between job location (i.e. whether home-based or non-home-based) and travel time (r = 0.581, p < 0.001); mode of transport to work and travel time (r = 0.634, p < 0.001)24 and TAZ origin and destination of work trips and travel time 25 (r = 0.547, p < 0.001). A positive association was also found between home-work distance and travel time (r= 0.597, p < 0.001). Based on the above relationships, a linear regression model was fitted to quantify the extent to which these factors determined total work travel time (see table 5.10)
Table 5.10: Determinants of work travel times
Independent Variables
Unstandardized Coefficients Standardized Coefficients
t Sig.
B Std. Error Beta
Constant -26.220 3.648 -7.188 .000
Travel-mode (walk vs motorized) 20.605 2.189 .302 9.412 .000
Travel mode*Distance .326 .110 .092 2.959 .003
Work location (home-based vs
non-home-based) 17.371 2.278 .232 7.627 .000
TAZ Origin and Destination 11.631 1.930 .179 6.026 .000
Note: R2 = 0.45
The results of the analysis show that using motorized transport was associated with seven- minute increase in travel time. This is reasonable since as indicated earlier, most non-home- based work travel, which are completed using vehicles also tend to be longer compared to home-based work trips which involve relatively shorter or no travel distance and are mainly completed as walking journeys. Indeed, non-home-based work location increases time of commute by about seven minutes. Controlling for other factors, the effect of the interaction term specified between travel mode and travel distance, though statistically significant is almost negligible. Finally, travel time increases by almost 11 minutes if one’s trip origin TAZ is different from their trip destination TAZ. The model could account for 45% of the variance in commuting times.
24 Transport mode was dichotomized into two categories; (i) non-motorized—walking) and; (ii) motorized—
private car and public transport
25 TAZ origin and destination of trips was dichotomized into two categories; (ii) whether TAZ origin and