Analysis and modeling of mixed land use and its effects on travel parameters
5.8 Conclusions
In this study, the relationship between travel behavior and the land use variables has been modeled in the context of smaller Indian cities. Travel behavior was quantified in terms trip
lengths, motorized/non-motorized mode choice, motorized private and public/IPT mode choice as well as the choice of individual modes. Land use mix has been measured using entropy, area index, DI, and mix type index. Approach used in calculating the entropy and DI was slightly different from that of conventional approach. Area index has been calculated for origin and destination of trip and this index takes different values based on the trip purpose. In quantifying the mix using modified DI and Mix type Index, cell size of 10m x 10m and grid size of 1km x 1km have been used. Entropy measured with 1000m buffer performed better than the entropy measured using the conventional method. The following are the important conclusions drawn out of the present work on land use and travel behavior interaction;
When slightly modified approach was used for calculating the entropy and DI, both the land use parameters were able to quantify the land use mix and were consistently having significant effect on the travel parameters.
The trip length of individuals, for both the shopping and work trips, was strongly correlated to the land use mix variables, even when controlling the socioeconomic characteristics. In case of work trips, entropy measured with 1000 m radius buffer, and DI measured using 10 m x 10 m cell for 1km x 1km tract were found to be more significant than the conventional entropy and dissimilarity indices measured for census tract. When the area Index for both the origin and destination were considered, there was almost 395% increase in the model’s ability to explain the variability of trip length compared to the base model. The coefficient of land use mix and intersection density at trip origin is negative which means an increase in intersection density and land use mix tends to reduce the trip length. With respect to socioeconomic variables, older people generally have shorter trip length. Private vehicle ownership has significant effect in explaining the variability of trip length.
With increase in private vehicles in a household, the trip length increases.
All the land use variables were negatively correlated with the trip length for shopping trips. In case of both shopping and work trips, older persons seem to go to closer destinations (shorter trip length). Similar to work trip, both the coefficient of land use mix and intersection density at the origin of the trip is negative, thereby
reducing the trip length. Apart from age, private vehicle ownership has a significant effect in explaining the variability of trip length in the modelling.
From the estimated binary logit models, it can be said that along with the socioeconomic parameters, land use parameters are also significant in explaining the mode choice. Area Index values, for both origin and destination, were found to be significant. Out of various socioeconomic variables tried in this study, years of education, gender, license status, and private vehicle ownership were found to be significant. As expected, having driving license, motorized vehicle ownership, and years of education reduces the utility of non-motorized modes. With respect to gender, male generally uses non-motorized modes. An increase in area index at origin and destination was also found to be enhancing the utility of non-motorized travel. Even when controlling for the socioeconomic characteristics, land use parameters have significantly improved the model. (Goodness of fit improved by 24.46%).
A significant elasticity exists (0.535) between the intersection density and the utility of non-motorized modes, for work trips. This may be due to the availability of more cycle rickshaws in the areas where the intersection density is high. In case of shopping trips, land use mix measured by entropy and DI in conventional way was insignificant. This clearly shows the disadvantages of entropy index measured for census tract and DI measured using 100 m x 100 m cells for census tract. Land use mix measured using a slightly different approach, could sufficiently capture the variations in the mode choice.
Similar to the work trip models, in case of shopping trips socioeconomic parameters such having driving license, motorized vehicle ownership and years of education reduces the observed preference heterogeneity of the non-motorized modes. Male in general uses NMT modes more often than females. Even when controlling for the socioeconomic characteristics, land use parameters have significantly improved the model (goodness of fit was improved by 33 %). Coefficient corresponding to area index for commercial area at origin was found to be significant, and implies a higher preference for non-motorized modes with increase in mixed land use.
Intersection density, measured as number of intersections per 1000m x 1000m cell,
was also found to be significant implying an increase in non-motorised mode preference with increase in intersection density.
In case of motorised private and public/IPT mode choice for work trips the utility of choosing private mode increases with the increase in the intersection density, which is counterintuitive. This may be due to the upper middle class people, owning vehicles, residing in mixed land use area. In this case the effect of mixed land use was found to be negligible. Same is the case with the shopping trips also.
In case of work trips, land use quantified by entropy index (buffer) and intersection density has higher elasticity than area index. This may be due to basic difference in the way the land use mix parameters were quantified. An increase in area index by 1
% increases the probability of choosing NMT modes by 0.321 %.
From the MNL models estimated on the mode choice for work trips, area index, entropy with 1km buffer. DI with 10m x 10m cell, and mix type index with 10m x 10m were found to be significant. The coefficients are positive for public and non- motorized transport which implies that the trip makers residing in the areas with mixed land use prefer public and non-motorized transport. Conventional DI and entropy indices were not able to capture the effect of land use mix for public transport; but they were significant in capturing the effect of mixed land use on NMT modes. It can be seen that the probability of choosing walk and cycle rickshaw increases with the increasing land use mix. An increase in area index by 1
% increases the probability of choosing cycle rickshaw by 0.265%. In case of motorized modes, the elasticity values with respect to choosing public transport are not strongly related. The elasticity of NMT is higher than public transport modes.
From these conclusions, it can be said that the land use mix variables, along with some of the other land use parameters, significantly influence the non-motorized transport mode choice for work as well as for shopping trips. Any change in the existing mixed land use pattern further shifts people towards the personal mode of travel.
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