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Computation

• Accessible region R:

  R = ∑ i = 1 n a i R = \sum_{i=1}^na_{i} R=i=1∑n​ai​

• Service population S:

  S = ∑ i = 1 n a i ∗ p i S = \sum_{i=1}^na_{i}*p_{i} S=i=1∑n​ai​∗pi​

• Service population indicators:

  P = ∑ i = 1 n a i ∗ p i T i P = \sum_{i=1}^n\frac{a_{i}*p_{i}}{T_{i}} P=i=1∑n​Ti​ai​∗pi​​

• The shortest routes from Tanggu Railway Station to other grids
  1. Only by road: T 1 = ∑ i = 1 n t i T_{1} = \sum_{i=1}^nt_{i} T1​=i=1∑n​ti​
  2. Only by railway: T 2 = t j T_{2} = t_{j} T2​=tj​

  3. Railway + Road: T 3 = T 2 + ∑ i = 1 m t q T_{3} = T_{2} + \sum_{i=1}^mt_{q} T3​=T2​+i=1∑m​tq​

     Accessibility measure of a given location:

     A i = ∑ j = 1 , j ≠ i C i j    o r    A i = 1 n ∑ j = 1 , j ≠ i C i j ( i , j = 1 , 2 , ⋯ ， n ) A_{i} = \sum_{j=1,j\neq i}C_{ij} \ \ or\ \ A_{i} = \frac{1}{n}\sum_{j=1,j\neq i}C_{ij} (i, j = 1, 2,\cdots，n) Ai​=j=1,j̸​=i∑​Cij​  or  Ai​=n1​j=1,j̸​=i∑​Cij​(i,j=1,2,⋯，n)

     Accessibility measures C i j C_{ij} Cij​

     Travel time : A t i = ∑ j = 1 n T i j n − 1 At_{i}=\frac{\sum_{j=1}^nT_{ij}}{n-1} Ati​=n−1∑j=1n​Tij​​

     Travel distance: A d i = ∑ j = 1 n D i j n − 1 Ad_{i}=\frac{\sum_{j=1}^nD_{ij}}{n-1} Adi​=n−1∑j=1n​Dij​​

     Travel cost: A p i = ∑ j = 1 n P i j n − 1 Ap_{i}=\frac{\sum_{j=1}^nP_{ij}}{n-1} Api​=n−1∑j=1n​Pij​​