Building a Bridge

Question

Your task is to build a bridge to connect two cliffs given an input d, the distance apart. d will always be even

However, the bridge needs columns to hold it up. Each column can hold a max of 6 spaces on each side.

For this example:

________                        ________
        |                      |
   A    |                      |   B

        |----------------------|
                d = 22

The bridge for d = 20should look like this with two columns. Columns do not count in d.

_____|__________|_____
12345|1234554321|12345
     |          |

Rules:

1. Must have enough columns to stand up.

2. Must have minimum number of columns needed to stand up.

3. Must be symmetrical

4. Lowest amount of Bytes Wins

Examples: (#s are only to help you count spaces. Should not be included in your output)

d = 10

_____|_____
12345|12345
     |

d = 32

_____|___________|___________|_____
12345|12345654321|           |
     |           |           |

d = 8

____|____
1234|1234
    |

d = 4

__|__
12|34
  |

d = 22

_____|____________|_____
12345|123456654321|
     |            |

or

______|__________|______
123456|1234554321|123456
      |          |

Answer 1

JavaScript (ES6), 92 bytes

d=>[..."_  "].map(c=>(s=c+c[r='repeat'](n%6))+'|'+(c[r](12)+'|')[r](n/6)+s,n=d-1>>1).join`\n`

Where \n represents the literal newline character. If d can be odd, it takes me 128 bytes:

d=>[..."_  "].map(c=>[...Array(d+1)].map((_,i)=>(d&1?i&&d-i&&(i>m)+5+i-m:((d-1)%24>11)*6+i-m)%12?'':'|',m=d>>1).join(c)).join`\n`

Answer 2

Ruby, 108 bytes

Probably can be golfed down a lot more. Greedy algorithm.

->d{s='',k=6
(s+=?_*[d,k].min+(d>k/2??|:'');d-=k;k=12)while d>0
s=s.chomp(?|)+s.reverse+$/
s+s.tr(?_,' ')*2}