Din cate imi mai amintesc eu, drumurile secundare sunt chiar "secondary roads," si nu "spurs." De asemenea, nu cred ca in Romania exista autrostrazi varianta ca in SUA. Highway spurs au cam acelasi statut is importanta ca si autostrazile, numai ca sunt variante sau bifurcatii in jurul unor conglomerate urbane, dar merg in general cam in acelasi sens ca si autostrada.

Nu stiu daca exista termenul in romana, deci nu sunt deloc sigura, dar cred ca asta e sensul.

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Note added at 15 hrs (2007-11-26 13:30:35 GMT)
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Cred ca infrastructura rutiera romaneasca pur si simplu nu e suficient de dezvoltata ca sa aiba termeni consacrati pentru toate aceste drumuri. Mai exista si beltway (care ar trebui sa fie "sosea de centura", dar dupa ce am citit descrierea din Wikipedia, cred ca traducerea ta pt. bypass road e buna.

Nu cred insa ca bretea e acelasi lucru. Aceste spurs sunt drumuri in toata regula, am mers peste 100 de mile pe unul. Sunt pur si simplu ramificatii varianta ale unei autostrazi, notate de la 1 la 9, care iti ofera posibilitati de transport in apropierea unui conglomerat urban. Eu stau in Philly, unde se intersecteaza I95 cu I76 (unde I=Interstate). (Apropo: autostrazile cu numere pare merg de la est la vest, cu numere impare, de la nord la sud). Si din 95, si din 76, se ramifica o gramada de "spurs" (desi nimeni nu le numeste asa, btw: asta e un termen mai tehnic): 476, 276, 295, etc. Ca sa le vezi, du-te la Google maps, cauta Philadelphia, si observa cum sunt autostrazile prin preajma.

"A spur route is a short road forming a branch from a longer, more important route (typically a major road, freeway, Interstate Highway or motorway). A bypass or beltway is never considered a true spur route as it typically reconnects with the major road. Both loops and spurs are forms of auxiliary routes.

In the US, many Interstate Highways have spur routes when they enter a large metropolitan area. Interstate spur routes are numbered with a three-digit number. The last two digits of the number are the number of the "parent" Interstate; e.g. a spur route of Interstate 90 would be 490, a spur route of Interstate 5 would be 805.

Spur Interstate routes have three digit numbers with an odd first digit, while a subsidiary route either passing through a city or bypassing it would receive an even first digit. For example, in the case of Interstate 5's spur routes in Los Angeles, Interstate 405 goes through the entire city, whereas Interstate 105 ends at Los Angeles International Airport.

Spurs can be branches off of other highway types, too (US highways, state routes, etc.), often as extended onramps and offramps of expressways.

There are many numbering violations in the spur route numbering system, thus the general rules above do not always apply.
(http://en.wikipedia.org/wiki/Highway_spur#United_States)

Deci tot ramificatie/bifurcatie (desi nu e chiar "bi" ci "multi" :) sau varianta ar merge.