1、Bradley L. Mallory, PresidentSecretaryPennsylvania Departmentof TransportationAmerican Association ofState Highway and John C. HorsleyTransportation Officials Executive DirectorExecutive Office: 444 N. Capitol St., N.W., Suite 249, Washington, D.C. 20001Telephone (202) 624-5800 Telefax (202) 624-580
2、6 Telex 49000095800 HTODear Customer:Recently, we were made aware of some technical revisions that need to be applied to the Guidelines forGeometric Design of Very Low-Volume Local Roads (ADT 400).Please replace the existing text with the following revisions to ensure that your edition is both accur
3、ate andcurrent.AASHTO staff sincerely apologizes for any inconvenience.AASHTO Publications StaffAugust 2002Technical Corrections(1) On page 45, replace Exhibit 14 with the following table:Metric US CustomaryDesign speed (km/h) Sight distance (m) Design speed (mph) Sight distance (ft)20 20 15 7030 25
4、 20 9040 35 25 11550 45 30 14060 55 35 16570 65 40 19580 75 45 22090 90 50 245100 105 55 28560 325Note: For approach grades greater than 3%, multiply the sight distance value by the appropriateadjustment factor from Exhibit 15.Exhibit 14. Recommended Sight Distance Guidelines for New Construction of
5、Intersections with No Traffic Control (Case A) (1, 6)(2) Also, in the last line of text of the first paragraph on page 45, change “80 m 255 ft and40 m 120 ft” to “75 m 245 ft and 45 m 140 ft” so that the text reflects the revisionsthat were made in Exhibit 14.(3) On page 46, replace Exhibit 15 with
6、the following table:MetricDesign speed (km/h)Approachgrade (%) 20 30 40 50 60 70 80 90 1006 1.1 1.1 1.1 1.1 1.1 1.1 1.2 1.2 1.25 1.0 1.0 1.1 1.1 1.1 1.1 1.1 1.1 1.14 1.0 1.0 1.0 1.1 1.1 1.1 1.1 1.1 1.13 to +3 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0+4 1.0 1.0 1.0 1.0 0.9 0.9 0.9 0.9 0.9+5 1.0 1.0 1.0 0.9
7、 0.9 0.9 0.9 0.9 0.9+6 1.0 1.0 0.9 0.9 0.9 0.9 0.9 0.9 0.9US CustomaryDesign speed (mph)Approachgrade (%) 15 20 25 30 35 40 45 50 55 606 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.2 1.2 1.25 1.0 1.0 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.14 1.0 1.0 1.0 1.1 1.1 1.1 1.1 1.1 1.1 1.13 to +3 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.
8、0 1.0+4 1.0 1.0 1.0 1.0 0.9 0.9 0.9 0.9 0.9 0.9+5 1.0 1.0 1.0 0.9 0.9 0.9 0.9 0.9 0.9 0.9+6 1.0 1.0 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9Note: Based on ratio of stopping sight distance on specified approach gradeto stopping sight distance on level terrain.Exhibit 15. Adjustment Factors for Sight Distance Based onApproach Grade (1, 6)
