ML20149E690

Applicant Exhibit A-14,consisting of Undated Page 8-6 of Article on Rural Highways

ML20149E690
Person / Time
Site:	Seabrook
Issue date:	11/15/1987
From:	AFFILIATION NOT ASSIGNED
To:
References
OL-A-014, OL-A-14, NUDOCS 8802110236
Download: ML20149E690 (1)

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Tastt 8 2. Ltyr.t..or 3tavict CatTtnir ton Srterne OnAors k kg is virtually impossible under lesel-of senice E condi-tions, and platooning becomes intense when slower vehicles or Ltvil OF 51R$ fCE AvrRAGE tJPOR ADE sPr ED tMPH) other interruptions are encountered.

EMe kh A threapacity of the highway. Under ideal conditions, capacity 2 55 B a 50 is 2,800 peph, total in both directions. For other conditions, C 2 45 QUlQ y capiscity$ lower Note that the v/c ratios of Table 81 are not f

F 2 $40, 25- W 00CKEliMaa fionlufspacity. This is because the ratios are relatise to BR Attfeil capacity" as discussed. Operating conditions at capacity are unstable and dimcult to predict. Trame operations are sel-

• The etast steed at ohnh capace cm. curs v.ne. .iih ine perceatase *" dom obsened near capacity on rural highwap, primarily be-rh s iame rat =. and wiume: computunal praedum e' cause of a lack of demand.

Capacity of two-lane highways is ulected by the directional split of trame. As directional split moses away from the 50/

50 "ideal" condition, total two-way capacity is reduced, as well below passing capacity, and almost no platoons of three v follows:

more schicles are obsened Drners would be delayed no more than 30 percent of the time by slow-moving vehicles. A mam Directional Total Ratio of Capacity to Split Capacity (pcpv / deal Capcory mum flow rate of 420 peph, total in both directions, may t achieved under ideal conditions. 50/50 2,800 1.00 Levelofsenice B characterizes the region of trame flow e0/40 2.650 0 14 70/30 2.500 019 wherein speeds of $$ mph or slightly higher are expected c<

level terrain. Passing demand needed to maintain desired speed becomes Sigruficant and approximately equals the passmg cm N

100/0 2.000 Ofri pacity at the lower boundary of level of senice B. Dnvers ar.

delayed up to 45 percent of the time on the average. Servie For short lengths of two lane road, such as tunnels or bndges, flow rates of 750 pcph, totalin both directions, can be achiever opposing trame interactions may have only a minor effect on under ideal conditions. Above this flow rate, the number o' capacity. The capacity in each direction may approximate that platoons forming in the trame stream begms to increase dra of a fully loaded single lane, given appropriate adjustments for matically. the lane width and shoulder width (5). 3 Further increases in flow characterize /crelofsentcc C. re As with other highway types, level-ofsenice F represents W '

sulting in noticeable increases in platoon formation, platoon size, heanly congested flow with trame demand exceeding capacity.

and frequency of passing impediment. Average speed still ex- Volumes are low er than capacity, and sps ds are below capacity ceeds 52 mph on lesel terrain, esen though unrestricted passinf speed. Lesei-ef senice E is seldom attainal over extended see-demand exceeds passing capacity. At higher volume levels- tions on level terrain as more than a transient condition: most chaining of platoons and significant reductions in passing ca- often, perturbations in trame flow as level E is approached cause pacity begin to occur. While traffic flow is stable, it is becommF a rapid transition to leve!-of senice F, susceptible to congestion due to turning trame and slow-moving schicles. Percent time delays are up to 60 percent. A senice flow rate of up to 1,200 peph, total in both directions, can be accommodated under ideal conditions.

Unstable trame flow is approached as trame flows enter level.

of senice D. The two opposing trame streams essentially begin OPERATIONAL ANALYSIS to operate separately at higher volume levels, as passing becomes extremely diflicult. Passing demand is sery high, while passing This section presents the methodology for operational analy sis espxity approaches zero. Mean platoon sizes of 5 to 10 vehicles of general terrain segments and specific grades on two-lane ere common, although speeds of 50 mph can still be mamtained highways. Separate procedures for general highway segments under ideal conditions. The fraction of no passing zones along and grades are used, because the dynamics of trame interaction i the roadway section usually has httle influence on passing. Turn- on sustained two lane grades differ from those on general terrain ing schicles and/or roadside distractions cause major shock- Segments. Grades of less than 3 percent or shorter than 1/2 wases in the trame stream. The percentage of time motonsts mile may be includ:d in general terrain analysis. Grades both are delayed approaches 75 percent. Maximum senice flow rates longer and steeper than these values should generally be treated of 1,800 peph, totalin both directions, can be maintained under as specific grades. Lesel, rolling, and mountainous terrain are ideal conditions. This is the highest feow rate that can be main. as defined in CLpters I and 3.

tained for any length of time oser an extended section of sevel The length of grade is taken to be the tangent length of grade  ;

terrain without a high probability of breakdown. plus a portion of the sertical curves at the beginning and end .

Levelof senice E is defined as trame flow conditions on two- of the grade. About one fourth of the length of vertical cunes lane highways hasing a percent time delay of greater than 75 at the begmning and end of a grade are included in the grade g \

percent. Under ideal conditions, speeds will drop below 50 rcph. length. Where two grades (in the same direction) are joined by y ,

l Aserage trasel speeds on highways with less than ideal condi- a sertical cune, one half the length of the cune is included in t

tions will be slower, u low as 25 mph on sustained upgrades. each grade segment.

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