Highway Engineering

54 Highway Engineering

Computation of discounted benefits and costs

Table 3.3 gives the valuations for the three user benefits over the 10 years of the

upgraded highways operating life.

Year Predicted flow Construction cost Operating cost

(10^6 v.km/yr) (£) (£)

1— 15000 000 —

2— 10000 000 —

3 250 — 500 000

4 260 — 500 000

5 270 — 500 000

6 280 — 500 000

7 290 — 500 000

8 300 — 500 000

9 310 — 500 000

10 320 — 500 000

11 330 — 500 000

12 340 — 500 000

Table 3.2Tr a ffic flows

and costs throughout

economic life of the

highway proposal

Accident cost Operating Travel time Total user Discounted

savings cost savings savings benefits benefits

Year (£) (£) (£) (£) (£)

1— — — — —

2— — — — —

31 500 000 454 963 6 617 647 8 572 610 7 197 729

41 560 000 473 162 6 882 353 8 915 515 7 061 923

51 620 000 491 360 7 147 059 9 258 419 6 918 429

61 680 000 509 559 7 411 765 9 601 324 6 768 554

71 740 000 527 757 7 676 471 9 944 228 6 613 480

81 800 000 545 956 7 941 176 10 287 132 6 454 274

91 860 000 564 155 8 205 882 10 630 037 6 291 902

10 1 920 000 582 353 8 470 588 10 972 941 6 127 233

11 1 980 000 600 552 8 735 294 11 315 846 5 961 046

12 2 040 000 618 750 9 000 000 11 658 750 5 794 042

S=65 188 612

Table 3.3Valuations of discounted highway user benefits

Taking the computations for year 7 as an example, the three individual user

benefits together with their total and discounted value are calculated as follows:

Accident savings(Yr 7) =(0.85 -0.25) ¥10 000 ¥ 290

=£1 740 000

Operating cost(existing route) =(2 +35/40 +(0.00005 ¥ 402 )) ∏ 100

=£0.02955 per km per vehicle

Operating cost(upgraded route) =(2 +35/85 +(0.00005 ¥ 852 )) ∏ 100

=£0.02773 per km per vehicle