Density Of Road Network Study Based On Floor Area Ratio

Traffic congestion is a frequent problem in modern cities,especially in some high-density and high-intensity development areas.There are many reasons for congestion,but the root is the imbalance between traffic supply and demand.In the stage of urban planning,it is an important measure to pay attention to the balance of supply and demand to alleviate traffic congestion.Planning a reasonable road network structure and determining reasonable road network density are the guarantee of traffic supply.At present,the planning work is generally based on Code for Transport Planning on Urban Road(GB50220-95),and the reasonable road network density is determined according to the population size of the city.But in reality,many areas planned according to the Code for Transport Planning on Urban Road are facing serious traffic congestion.Therefore,in the planning stage,land use factors should be taken into account in determining the density of road network instead of urban and population size.The nature of the area and the intensity of development essentially reflect the characteristics of the traffic demand.Based on the above,this paper studies the variables that affect the density of road network from the characteristics of land blocks and discusses the relationship between them.First of all,the research and methods of existing road network density are summarized.Based on the theory of supply and demand balance,introducing the floor area ratio(FAR)factor to characterize the development intensity of the blocks,a road network density model is established,and the parameters calibration in the model is analyzed.Based on that,a high-density cluster land is selected as an example to analyze the sensitivity of the key parameters of the model.It is found that the sensitivity of road area rate upper limit is high,the sensitivity of road width,road network density,branch network density sensitivity are low,the sensitivity of travel structure is high,and the sensitivity of FAR and nature of land property are high.Therefore,we should take the analysis of the value of the upper limit of the road area rate,the travel structure,the FAR and the nature of the land use on different conditions,and other parameters can be used on average.The land distribution of high density group land in Ji'nan is selected as an example.The influence of FAR on the density of road network is analyzed under the travel structure of the upper limit of road area rate of 20%,25%,30%,and the travel structure of Ji'nan's current situation,bus oriented and car oriented transportation development mode.Comparing the calculation results of the road network density model with the(GB50220-95),the influence of the average FAR on the road network density is roughly four obvious stages,and the(GB50220-95)is only applicable to the situation with low development intensity and low average FAR within 1.5.The average FAR and road network density have upper limit value under the travel structure of each traffic development model and the upper limit of the road area rate.Therefore,it's not reasonable to increase the volume of development without consideration.In the reasonable range of average FAR,the value of road network density increases with the increase of FAR.With the increase of the upper limit of the road area rate,the upper limit of the average FAR increases with the travel structure of each traffic development model.It shows that increasing the road area rate can increase FAR.With the same road area rate upper limit of different traffic development mode,bus oriented traffic development mode can get higher FAR than other traffic development modes.The actual area of three typical land combination in Ji'nan are selected as examples.Under the travel structure of Ji'nan,the influence of the FAR on the road network density is analyzed for the three typical urban land combination of residential business office,industrial residence and business industry.Eventually come to the conclusions: The change of average FAR of different land use combinations is different,but the trend of change is the same.The density of road network increases with the increase of FAR.The upper limit of the average FAR of the commercial industrial land combination is higher than that of the residential industrial land combination area,and the upper limit of the average FAR of the residential commercial office land is the lowest.Therefore,the reasonable value of road network density should not only take into account the FAR of the area,but also consider the land use nature of the land blocks group.