Reducing h ighway speed by fivemiles per h our can cut fuel use a nd greenhouse gas emissions by over sev en percen t whil

e exte nding

the l ife of a truc k’s engi ne, ti res an d brak

es. A l ong-ha ul tru ck with

90 percent hi

ghway operationthat reduces i ts top speed from 70 to 65 miles per hour could cut its annual fuel bill by $1,450 while eliminating nearly ten metric tons of gre enhouse gas reductions.


## What is t he chall enge? A typical combination truc k s pends 65 percent or
more of its operatin g time at highway speeds. Linehaul truc ks spend even more ti me on highways. The impact of speed on fuel economy dep ends upon many factorsincludi ng vehicl e aerodyna mics, engine speed and operating conditions. As a general rule of thumb, increasing sp eed by on e mile per h our reduces fuel econo my by about 0.1 miles per gal lon. For a truc k with poor aerody namics, the fuel p enalt y may be ne arly

twi ce as gr

eat. Hi gher s p eed also lea ds to higher main tenance costs by increasi n g wear on th e engine, tires and brakes.


## What is t he solut ion? Speed management

is an easy

and effective

way to
save fuel, r educe em issions, and preve nt excess
w ear. A trucking firm or driv er can adopt a

s pee d policy at li ttle o r no co st. The most successful spee d managementpolicie s combine tech nolog y (e.g., speed setti ngs on e lectro nic e ngine contro ls) w ith driver training and incent ive prog ramsto e ncou rage drivers to maintain speed limi ts. Most new truck engines are electronicall ycontrolled so the cost of changing maximum speed settin gs on these engines is negligibl e.


## Th e re su lts a re in

. . . Alt houg h fuel savin gs may vary by vehicleand speed range, a national trucking associatio n estimates that
a combination truck drivin g 55 milesper hour uses up to 20 percent l ess fuel than a si milar truck driv ing 65 miles per ho ur. Other analy ses indica te that reducin g the maximum spee d of a typica l long-haul truck from 70 miles per h ou r to 65 miles pe r hour co uld save abou t $1,450 in annual fuel costs. Reducin g the maximum speed to 60 miles per h our could save an additional $1,850, bringi ng the estimated a n n ual savings to $ 3,300.
Reducing spe ed can c ut tr uck mai ntenan ce cos ts and reduce thefrequency of maintena nce work. The ti me b etween engine overhauls, for example, is directlyrelated to fuel use. Holdi ng maximum spee ds at60 rat her tha n 70 mi les per hour reduce s engine wear and extends ti me between engine rebuil ds, saving hundredsof dollars pe r truck each yea r while keeping revenue -ear nin g equ ipment on the road. Fleet s that

ado pt sp eed pol ici es re port add ed s avi ngs due to fewe r brake repla cements and o ther se rv ic e work.
Reducing highw

ay speed does increas e travel time. Assuming ideal co nditions, a trucker driving 6 0 miles per hour instea d of 65 miles pe r hour could spend about eight pe rc ent longer on th e road. Of course, the time difference may be less, de pending upo n road condi tions , wea ther, t raffic congestion, and ro ad constructio n

. If a truc king comp any p ays i ts dri vers by the mile o r by t he lo ad rath er than by th e hour

, reducing speed shoul d not incre ase l abor costs. It
cou ld r educe the prod uctivity of trucking operations since slower

trucks may carry

fewer loads

. However, the benefi ts of lower fu el an d main tenance costs combined with l ess frequent out-of-service work and driver safety consid erations may well o utweigh any costs a ssoci ated w ith i ncreas ed del iver y time

.


## Next st eps A trucking company interested in saving fuel and lowerin g the cos t a nd frequency of its e quipment maintenanceshoul d c onsider adopting a speed
man ag ementpolicy , particularl y if its trucks sp end considerable time on highways. A number of wellmanaged truc k f leetshave programs

in pl ace to
re duce highway spee d and prom ote saf e drivi ng b y using driv er t raining, ince ntive programs a nd electronic engine controls. A tru cking fleet interested in following these exam ples may l e arn more by reading articles and fleet p rofile s in t ruck in dustry publicatio n s. When purcha sing new vehicl es, a trucking company m ay a ls o consider s pecifying equipm entdesigned to o ptimize truc k performance a t lower maximum spee ds. Trucking companies and drivers interested in learning more a bout th e effects of speed on fuel econo my may contact truck and equipment

manufac

turersor their state an d national truckin g assoc iatio ns.