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H I G H W A Y R E S E A R C H B O A R D
Bulletin No. 43
N 0 V 2 i i y 6 /
8 E S E A R C H 0 0 ^
1 9 5 1
H I G H W A Y R E S E A R C H BOARD 1951
O F F I C E R S
Chuinnan ... R. A. MOVER Vice-Chairman R . H . BALDOCK Diiectof - F R E D BURGGRAF
E X E C U T I V E C O M M I T T E E
THOMAS H. MacDONALD
H A L H. H A L E
L O U I S JORDAN
R. H. B A L D O C K
H. P. B I G L E R
P Y K E JOHNSON
B U R T O N W. MARSH
R. A. M O V E R
F . V. R E A G E L
W. H. ROOT
C H A R L E S M. UPHAM
Commissioner, Roads
Bureau of Public
Executive Secretary, American Association of State Highway Officials
Executive Secretary, Division of Engineering and Industrial Research, National Research Council
State Highway Engineer, Oregon State Highway Commission
Birmingham, Alabama
President, Automot ive Safety Foundation
Director, Safety and Traffic Engineering Department, American Automobile Association
Research Engineer, Institute of T r a n s p o r t a t i o n and Traffic Engineering, U n i v e r s i t y of California
Engineer of Materials, Missouri State Highway Department
Maintenance Engineer, Iowa State Highway Commission
Consulting Engineer
E D I T O R I A L S T A F F
Fred Burggraf W. N. Carey, Jr .
The Highway Research Board is not responsible for the statements made and opinions expressed in its publications.
P U B L I C A T I O N O F F I C E S
2101 Constitution Avenue Washington 25, D. C.
H I G H W A Y R E S E A R C H B O A R D
Bulletin No. 45
SUBSURFACE DRAINAGE
PRESENTED AT THE THIRTIETH ANNUAL MEETING
1951
HIGHWAY RESEARCH BOARD DIVISION OF ENGINEERING AND INDUSTRIAL RESEARCH
NATIOIAL RESEARCH COUNCIL
Washington 25, D. C. , December 19SI
DEPARTMENT OF SOILS INVESTIGATIONS
Harold A l l e n , Chairman P r i n c i p a l Highway Engineer,
Bureau o f P u b l i c Roads
COMMITTEE CW SUBSURFACE DRAINAGE
P h i l i p Keene, Chairman Engineer o f S o i l Mechanics and Foundations,
Connect icut State Highway Department
Professor Edward S. Barber, Department of C i v i l Engineering, University of Maryland John A. C. Callan, A-118, Acting Chief, Standards Coordination Branch, Engineering
Division of Office of Airports, C i v i l Aeronautics Administration Kenneth E f f , Off ice , Qi ief of Engineers, Department of the Army Seward Homer, Qi ief Geologist, Kansas State Highway Commission Carl F. Izzard, Qiief , Hydraulics Research Branch, Bureau of Public Roads, U. S.
Department of Ccnnerce Professor C E. Jacob, Head, Department of Geophysics, School of Mineral Industries,
University of Utah Stanley J. Johnson, Oiief , Embankment and Foundation Branch, Waterways Experiment
Station, Vicksburg, Mississippi P. E. Masheter, Assistant Qi ief Engineer, Bureau of Construction, Ohio Department of
Hi^ways, Ohio Departments Building George W. McAlpin, Jr . , Director, Bureau of Soil Mechanics, New York Department of
Public Works, State Office Building Paul Otis, Materials and Research Engineer, New Hampshire State Hi^way Department 0. J . Porter, 415 Frelin^uysen Avenue, Newark, New Jersey Carl R- Reid, 625 Dunsmuir Avenue, Los Angeles 36, California Professor M. G> Spangler, Iowa State College W. T. Spencer, Soils &igineer, State Highway Comnission of Indiana, State House Annex Dr. Hans F. Winterkom, Director, Soil Science Laboratory, Princeton University
A REPORT OF THE COMMITTEE ON SUBSURFACE DRAINAGE
P R E S E N T PRACTICE IN SUBSURFACE DRAINAGE FOR HIGHWAYS AND AIRPORTS
Phi l ip Keene, Oiairraon, Connecticut State Highimy Department and Seward E. Homer, State Highway Commission of Kansas
SYNOPSIS
This paper i s a tabulation of repl ies to a questionnaire prepared by the Committee on Subsurface Drainage, Highway Research Board.
Nearly a l l rep l i e s stated that faulty subsurface drainage caused pavement fai lures , including rutting and shoving in f lexible pavements, pumping in concrete pavements and frost heaves and boils in both types of pavement.
P r a c t i c a l l y a l l r e p l i e s gave clogging of b a c k f i l l mater ia l , and sometimes pipe, as the chief cause of subsurface drainage f a i l u r e s . Under improvements since 1942, prac t i ca l ly a l l repl ies noted improved b a c k f i l l material ; their spec i f i ca t ions now c a l l for concrete sand, clean bank-run sand, or bank-run gravel (or the equivalent) for backf i l l with occasionally X-or I S - i n . stone given as an alternate. About half the organizations use either a f i l t e r test or the Vicksburg piping rat io c r i t er ion for f i l t e r design; the others make no test . The a l most unanimous use of clean, sandy b a c k f i l l i s in marked contrast to the e a r l i e r practice where three-fourths of the states used stone or screened gravel . P r a c t i c a l l y a l l organizations use perforated metal pipe and t i l e pipe; some also use concrete pipe
As would be expected, the chief use of underdrain instead of deep ditches occurs where the latter would be a t r a f f i c hazard.
Depth of pipe invert or deep ditch varies between 2 and 6 f t . ; usual ly i t I S about 2 f t . deeper than the average frost penetration under a bare pavement. About two-thirds of the states report that subbase i s carr ied out to f u l l width of shoulders; the balance repl ied that I t I S carried only to 1 or 2 f t . beyond edge of pavement. Total thickness of surface, base, and subbase varies widely, of course, with conditions of fros t , s o i l , t r a f f i c , etc . and i s from 6 to 32 in . thick.
The replies on sand drainage wells show that four state highway departments have used them; repl ies from federal agencies included mention of them on about four dams or dikes and three a irports . In each case the results were favorable.
Questionnaires were sent to the highway departments of a l l states, to the division off ices of the U.S. Bureau of Public Roads, the U.S. Corps of Engineers, Department of the Army, the U.S. C i v i l Aeronautics Administration and the U.S. Bureau of Ifecla-mation. About 90 percent of these organizations replied. A l i s t of the 38 questions and a t abu la t i on o f a l l r ep l i e s w i l l b e found in Tables A, B, and C.
While irost questions pertained to present practice, some dealt with related matters, such as failures of subsurface drainage and t h e i r e f f e c t on the pavement, width and depth of subbase, depth of f ros t , ver t ical sand drainage wells, improvements i n pract i ce since the 1942 questionnaire on th i s subject (1) and research.
As a l l subsurface water originates from p rec ip i t a t i on o f ra in and snow, a map o f the county (Fig. 1) with precipitation contours (2) i s of interest. Judging from the replies, however, the amount of annual pre -c i p i t a t i o n does not greatly govern the a-mount of subsurface drainage problems. An exception to this i s found i n a few of our most ar id states, such as North Dakota and Nevada, which report that subsurface drainage i s not great ly needed because o f the dry climate.
For convenience i n c lass i fy ing the repl ies , the country was divided between the shaded area and the white area shownin Figure 1. This divis ion coincides approximately with the 40-in. precipitat ion contour and with the general soi l types, based on a pedological c l a s s i f i c a t i o n . So i l s i n the eastern and southern states (white area on map) are largely the more leached podzols and brown, gray-brown, red, and yellow podzolic soi ls . In the western areas pra i r ie soi ls , chernozems, chestnut soi ls , brown so i l s and the various desert so i l s predominate.
On the basis of so i l o r i g i n , the areas are somewhat less d is t inc t . However, a map o f the o r i g i n of United States so i l s (3) classes nearly one- th i rd of the western states as being i n non-soil areas while a much smaller non-soil area is found i n the eastern section. Both sections have large areas of residual so i l s . While both also have glacial and coastal plain so i l s , the largest areas of glacial so i ls are i n the
western states and coastal plain soi ls i n the eastern section.
Geologically, there i s perhaps no good basis for distinguishing one area from the other, although the difference in practice between individual states i n each area may be s t r ik ing and might o f f e r an interesting approach to a comparison of subdrainage practice.
The questionnaire submitted to the var i ous states was divided in to eight general headings which have been followed i n this analysis of repl ies . In general, the replies are as much remarkable for their d i versi ty as fo r any tendency to show trends or the development of standard pract ice throughout the coiintry. This apparent lack of standardization in subdrainage practice i n the d i f f e ren t states is a re f l ec t ion of the widely varied subsurface water conditions encountered and, to a lesser degree, of the usual var ia t ions i n personnel and o rgan iza t ion . A d e f i n i t e trend toward standardization i n the matter o f gradation of the backf i l l aggregate i s found.
Failures caused by subdrams. (Questions 2 and 20) - The seriousness of faul ty subsurface drainage was recognized by nearly a l l states, although no attempt was made to obtain quantitative data on the cost of poor subdrainage, such as was done in 1942. Most replies agreed i n substance with those o f Minnesota and Wisconsin, which stated that the majority of pavement fa i lures are due, ei ther d i r ec t ly or i nd i r ec t ly to excessive subgrade moisture. Only North Dakota and the South Pac i f i c Div i s ion of the Corps of Engineers reported no troubles from f a u l t y or inadequate subdrainage. North Dakota q u a l i f i e d th i s statement by point ing out that the nature of her problems were such that the practice of careful s o i l selection and the use of addit ional base and subbase thickness was generally followed i n place of subdrainage. I t i s in te res t ing to note also that t h i s state has a semi-arid climate and reports no rock cuts. Nevada and New Mexico indicated that the i r subsurface water problems were not severe.
Tbe types of fai lures attributed to poor subdrainage include almost every type common to either f l e x i b l e or r i g i d surfaces.
Of the 54 replies, 45 l i s t ed loss of sub-grade bearing capacity as a principal resul t of faul ty subsurface drainage. Frost heaving and subgrade softening due to the accumulation of water by f ros t action were mentioned in 24 replies, inasmuch as those states have re la t ive ly deep f ros t penetrat ion , at least in their mountainous areas. Several s tates (Maine, Massachusetts, Michigan, Minnesota, New Hampshire, North Dakota, Oregon, South Dakota, Vermont, Wisconsin, Wyoming, Washington, and Bureau of Public Roads Divisions Five (North), Eight, Nine, and Ten) reported depth of f ro s t of 5 to 8 f t . While more states mentioned damage to bituminous surfaces and f l e x i b l e pavements,. the number and variety of f a i l ures of concrete pavement l i s ted show cPear-1y that subgrade moisture conditions usually are equally important to e i ther type of surface. Arizona, however, reports that they do not use subdrainage adjacent to concrete pavement. Pumping o f concrete
pavements was l i s ted in e i ^ t replies, and one mention was made of deter iora t ion of concrete as resulting fron subsurface water conditions. I t i s not clear whether a d i rect or indirect e f f ec t was implied. However, there seems to be some minor evidence of a re la t ionsh ip between de te r io ra t ion (d-cracking) i n portland cement concrete and the occurrence of subsurface water i n the subgrade; more studies similar to those made by the Bureau of Public Roads (4) a few years ago on the chemicals of the soi l solution may develop some useful informat i o n on th i s common disease of concrete.
Kansas, Kentucky, and the Eastern Park and Forest Div i s ion of the BPR reported failures due to landslides which were caused by lack of underdrainage. Hie CM reported settlements due to movements of foundation soi l into the underdrain b a c k f i l l .
What criteria are used m establishing the need for subdrams and when are additional
— ANNUAL PRECIPITATION IN INCHES
Figure 1. Contours of Precipitation in the United States. Hie white states have more then 40 in . annual precipitation.
base thickness or deep ditches txsed m place of drams'' (Questions 3, U, 5, and 6.) -The replies to the question, 'What c r i t e r i a do you use i n deteripining i f subsurface drainage w i l l help stabilizethe subgrade?," at f i r s t seem remarkable for the i r divers i t y . However, i t must be realized that while the questionnaire deals w i t h sub-drainage as a general topic , the repl ies of ten have in mind the par t icular type of subdrainage ( interception, drawdown, base and subbase de-watering drains, e tc . ) with which the particular state i s most usually concerned. -Thus several r ep l i e s , 22 i n a l l , stress the permeability and gradation of the so i l as of prime importance i n determining the need for subdrains. Other replies l i s ted the depth to the water table as a f i r s t consideration. South Dakota and a few other states l i s ted the presence o f pervious layers over ly ing impervious material as a major point to be considered. Obviously, these states have many subsurface water problems which can best be dealt wi th by in te rcep t ion subdrainage. Texas and Kansas pointed out that the need f o r subdrainage can be predicted from a knowledge o f the geology of the area and of the type of material i n the subgrade.
In this connection i t can be noted that the use of geology i s becoming more recognized, and today a number of highway departments have f u l l - t i m e geologis ts on t h e i r s t a f f s ( 5 ) . Utah notes a need f o r subdrainage as a result of the construction o f i r r i g a t i o n canals near the roadway. I l l i n o i s reports the use of snow and ra inf a l l data in determining the need for sub-drainage. I t i s assumed that the type of subdrainage re fe r red to i n t h i s case i s base and subbase de-watering drains.
The apparent divers i ty of c r i t e r i a used i n e s t ab l i sh ing the need f o r subdrains points to the need fo r a standard nomenclature f o r drains. The analyses o f answers to many of the questions was d i f f i cu l t and uncertain, because the statements made did not apply to similar conditions. For example, where a drain i s intended to lower the water table, i t i s ent i re ly possible that several standard depths, varying w i t h the s o i l type, may be establ ished successfully. McClelland's charts (6) may be useful i n th i s . However, where the i n
tent of the drain i s to intercept the flow o f water i n a narrowly confined zone i n e i ther the so i l or bedrock, there can, o f course, be no thought of a standard depth.
Some states report that most of the i r subdrain i n s t a l l a t i ons are the resu l t of the uncovering of seeping water during cons t r u c t i o n or o f a f a i l u r e o f the road under t r a f f i c . The encouraging t rend, however, i s to use the s o i l or geological survey i n loca t ing drains i n advance o f construction. Ihere were indications that this practice may lead to the ins ta l l a t ion o f necessary underdrains at locations where no water was discovered due to dry weather, either during the subdrainage study or the const ruct ion. This c l ea r ly indicates a growing use of a fundamental knowledge of subsurface water.
Nearly every state indicated that addi t ional base or subbase i s sometimes subs t i tu ted fo r subsurface drainage i n soi ls of h i ^ cap i l l a r i t y . Although the question did not ask i t , probably these states use both subdrainage and additional subbase in certain cases. North Dakota (as previously mentioned) and Nevada report that good, cheap aggregate was widely enough d i s t r i buted i n the state to make possible short hauls . Thus i t i s cheaper f o r them to thicken the base than to ins t a l l subdrains. New Mexico, on the other hand, reports , "In those cases we have had to deal wi th , i t was cheaper to trench and use perforated pipe ( i e . , than to thicken the base) ." Division Nine of the Bureau of Public Roads states that the thickening of bases and subbases i s used because i t s experience has never given f u l l confidence in the results obtained with any subdrainage system. Kansas expresses the opposite view i n s ta t ing that the use of thicker bases and subbases has been generally unsatisfactory as a substitute for subdrainage. I l l i n o i s , Ohio, Vermont, (Connecticut, and the CAA report the two methods are o f ten used i n combination. In general the decision of which method to use seems to be based on r e l a t i v e cost and on the d r a i n a b i l i t y of the so i l as determined by the so i l survey.
In reply to the question 'Wien do you use an underdrain instead o f a deep d i t c h ' , " the principal objections to the ditch were the t r a f f i c hazard, cost and other con-
siderations m obtaining right-of-way, and the danger of erosion with deep ditches. Seven states never use d i t ches . Vost r e p l i e s , however, i nd ica ted tha t deep ditches were used when the three factors l is ted above were not major considerations. Several replies stated some preference for the d i t ch over subdrainage and one state (Minnesota) does most of i t s drainage by open ditch.
Of the 54 replies, 19 report the use of a single pipe to carry both surface and subsurface water, but 14 of these replies stated that this practice was used only i n exceptional cases.
Types and Causes o/ Failures m Subsurface Drains, (Question 1.) ~ The types o f f a i l u r e s of subsurface drains l i s t e d i n these repl ies are, i n order of number of times mentioned:
(1) S i l t i n g of b a c k f i l l . 33 rep l ies l i s t e d th i s type of fai lure .TTiis i s gen-e r a l l y a t t r ibu ted to too open a b a c k f i l l material. [Replies did not indicate whether fai lures of this type were continuing with the present trend toward finer,dense graded aggregate.
(2) Broken pipe. Hiis was mentioned i n twelve replies. Sh i f t ing of the alignment of pipe and s e t t l i n g are included i n th is category. Oregon, Washington and Eastern Park and Forest Roads BPR repor t pipe broken by landslides. Construction equipment and excess tamping were also blamed fo r breaks, as was heavy wheel-loads on airports.
(3) Poor maintenance of ou t l e t s . ( I n ten repl ies . ) Weed growth over the outlet promotes clogging or surface wash may stop the outlets. Some reported damage to outlets by maintenance equipment.
(4) (hogging of pipe by roots, i n s u f f i c i e n t g rade , or u n s p e c i f i e d cause.
(5) Poor locat ion, including i n s u f f i cient depth.
(6) Poor construction practice. (7) Freezing of the pipe at the out let . (8) Clogging of pipe by small animals
or their nests. Clogging of the out let by nests has occurred even where bars were instal led over the outlet .
The last f ive types were each mentioned about three times but undoubtedly t h e i r
occurrence i s more widespread. As they are less usual types of f a i l u r e s , many repl ies probably f a i l e d to mention them.
Improvenent i n Proctice since 19^2 and Present Field and Laboratory Research m Subsurface Drainage. (Question 9, 8, 7) -The most frequently mentioned improvement i n practice since the 1942 questionnaire has been in the improved grading of back f i l l material . This was mentioned i n 30 of 52 repl ies . Figure 2 gives for those states reporting in 1942 ( D a comparison between 1942 practice and present practice i n this respect. The solid-black bars represent the gradation used today, while the open bars represent the 1942 gradations. The f i r s t bar at the top of the f igure represents the gradation given by the Vicksburg tests. Note the trend toward f iner aggregate and dense gradations. This i s , o f course, i n l ine with the Vicksburg results (7).
Nine states report marked improvement i n performance as q resu l t of better and more complete investigations of subsurface water conditions. Hiree states, Oklahoma, Pennsylvania, and Wisconsin, have advanced i n the better use of subdrains with bases and subbases. Better marking of the outlets has given better maintenance i n I l l i nois.; Texas and New Hampshire report past t rouble wi th broken and misaligned pipe and now report improvement from the use of corrugated-metal pipe. Some of Oregon's d i f f i c u l t s l ide problems have been helped by using a hor izon ta l auger i n p lac ing 6 - in . concrete drain pipe. Two agencies report improvement by discont inuing the ins ta l la t ion of French drains.
While a wide appreciation and use o f the various papers previously published i n the Highway Research Board Proceedings on subsurface water and subdrainage were indicated, the amount of active research now going forward i n th i s f i e l d i s rather d i sappo in t ing . Only a few states even mentioned f i e l d observations of results of their subdrainage ins ta l la t ions . However, the practice i s probably more general than indicated. I l l i n o i s i s testing the e f f ec t on cap i l l a ry moisture of drains designed to allow the c i rcu la t ion of a i r . Laboratory studies of clay mineral-moisture re-
lat ionships are reported by Kansas. The e l ec t r i ca l resistance method of measuring subgrade moisture i s under investigation in Missouri. Oregon, Utah, and New Hampshire are studying subdrainage i n r e l a t i o n to p e r m e a b i l i t y and other s o i l i n d i c i e s . Wisconsin has already published the results of seme previous research (8). (jonnecticut w i l l continue research on f i l t e r tes ts , v a r i a t i o n o f f r o s t heave w i t h depth o f water table, and e f f e c t on heave of concrete sand b a c k f i l l compared with coarser b a c k f i l l (9) . Maryland i s conducting research on porous-concrete pipe f o r sand-drainage wells (10).
The Bureau of Reclamation reports the completion i n 1947 of a comprehensive program on protect ive f i l t e r s f o r hydraulic and s ta t i c structures, and the Ohio River Div i s ion o f the Army Engineers i s making a i r f i e l d pavement evaluation studies which include an analysis of the exis t ing drainage systems and t h e i r performance. The New &igland Division of the Army Engineers made extensive and comprehensive f i e l d and laboratory experiments on drainage of sub-base coarses i n 1945-46 (11), (12).
Type and Location of Pipe or Ditch (Questions 11 to 22) - Very l i t t l e standardiza t ion i s to be found i n type or size of pipe, ins ta l l a t ion , depth of drain, 'or lo cation of trench. There i s , however, rather complete agreement among a l l agencies that perforations should be ins ta l led down unless the pipe i s used i n the ou t l e t sect i o n . Since they also state that size and spacing o f pe r fo ra t ions conform to the l a t e s t AASHO speci f ica t ions , t he i r pipes have perforat ions below the middle and a 90-deg. arc o f s o l i d i n v e r t . Only nine (Maine, Massachusetts, (jonnecticut, Misso u r i , North Dakota, (Sdahoma, Oregon, the Los Angeles D i s t r i c t , (jorps of Engineers, and the CAA) i n s t a l l the perforat ions up and then usually only fo r special s i tuat ions . A l l except three agencies report that size and spacing of holes conform to the latest AAEHO recoimendations.
Perforated corrugated-metal pipe i s the most generally used type. Ten agencies l i s t e d only t h i s type. Most states and federal agencies allow the use of several d i f f e r e n t types of pipes. Next to cor
rugated-metal pipe, open-joint t i l e is most frequently used. I t i s followed in order of popularity by open-joint reinforced concre te , perfora ted t i l e , clay sk ip , and porous-wall concrete pipe.
Most states using open-joint pipe require that the j o i n t be covered by either burlap or tarpaper, although some use sections of broken t i l e or require mortaring one h a l f o f the j o i n t . Ohio uses only sealed j o i n t s i f w i th in 25 f t . o f trees. Bell and spigot pipe i s , of course, genera l l y spec i f ied to be l a i d wi th the b e l l upstream. Some agencies, especially the Army Engineers, require wedging and shinm-ing of open-joint pipe to insure accurate alignment.
While the most common size of pipe used i s 6 - in . diameter with 8- in . pipe next i n popularity, every size from 4 to 24 i n . was reported.- Most agencies allow a variation to f i t d i f f e r e n t s o i l and ground-water conditions.
Hiere i s l i t t l e standardization of the horizontal distance of e i ther a d i tch or underdrain from the edge of the pavement, and there has been a healthy trend away from standardization of depth o f d ra in . Twenty-four reporting agencies place their subdrains at or very near the pavement edge. However, others place them any place between centerline of the road and the toe of the backslope. Most common loca t ion seems to be either near the pavement edge or the edge of the shoulder. Deep ditches are placed at any distance from 8 to 75 f t . from the pavement edge, and there appears to be no mean or normal distance. The need fo r beims for t r a f f i c safety was mentioned i n some repl ies . In a i rpor t construction pract ice, subdrains are generally placed at the pavement edge, but i n some cases are reported at distances of 75 f t . from the pavement edge. Deep ditches are, of course, kept a considerable distance from runways; distances of 100 to 400 f t . were reported.
The usual depth of pipe invert or bottom of ditch below the pavement surface varied from 2 to 7 f t ; 4 to 5 f t . i s about average. This undoubtedly represents an increase in depth over the 1942 practice in many cases. Nearly every s ta te reported a var iab le depth, the depth generally changing wi th the type of s o i l , the depth to the water
table, the depth of f ros t penetration, and fo r interception drains, the depth of the impervious layer below the aquifer. Sub-drains for airports are generally drawdown types and more frequently use a standard depth, varyingtomeet d i f f i c u l t outlet conditions or to obtain a self^cleansing gradient or to avoid crushing the pipe under wheel loads.
Obtaining an adequate out le t i s not a serious problem i n most states, although several o f the states i n the g lac ia ted area and the plains states report th is to be an occasional d i f f i c u l t y . The Eiureau of Reclamation reports that i n underdrains. fo r some canal l in ings i t i s necessary to pump the water from the drains. The problem of the plugged o u t l e t i s , however, rather widespread. The pr inc ipa l points stressed i n this respect were the need for obtaining outlets which require a minimum of maintenance and the need for a def in i te out let maintenance program. This requires pos i t ive marking o f a l l ou t le t s so they w i l l be constantly brought to the maintenance man's at tent ion. No information was obtained on the number o f states using headwalls on outlets or the types of head-walls used. However, these were mentioned as an aid in reducing maintenance.
Backfill Specifications and Placement (Qiestions 23 to 30) - The most significant feature of the gradation of b a c k f i l l mater ia ls i s shown i n Figure 2, which conpares the 1942 and present gradations of various states. Table C shows the gradations used today by nearly a l l s ta tes . I t can be noted tha t while the trend has been to dense, f iner gradation, alternate spec i f i cations f o r several states s t i l l permit coarse, open gradings. While 29 of the 54 reporting agencies use essentially the same gradation for a l l type so i l s , many states l i s t a l ternate gradations which may, i n some cases, as i n Kansas, r e f l e c t local a v a i l a b i l i t y of materials or may indicate the use of a coarser gradation over jo in t s and perforations. Seven agencies provide for special gradations to meet special conditions but indicate that special cases are rare . Ten agencies check the design o f b a c k f i l l material against each s o i l encountered. In general, there seems to be
less emphasis on special gradations and two-layered gradations than i n 1942, probably because perforations are nearly always down. Since the trend has been to use a gradation approaching the general type recommended in the Vicksburg experiments, support i s given to the adequacy of those experiments.
Ten states and six federal agencies regular ly make tests either of the permeability of the b a c k f i l l or calculate piping rat ios to determine the gradation o f b a c k f i l l aggregate to be used. Most states, however, have concluded that material agreeing i n gradation with the Vicksburg tests i s useable f o r most o f t h e i r so i l s and do not make tests at each location.
Sixteen agencies usual ly use coarser material at perforations and open j o i n t s . I l l i n o i s and Indiana follow this practice i n special cases. This two-layer system requires some hand placing. Missouri, and occasionally Connecticut, uses a three-layer system, with f i n e l y graded material i n the bottom of the trench followed by coarser material around the pipe or over the perforat ions, i f they are up, and i n t u rn by f i n e r mater ia l above the pipe. Alabama and the C i v i l Aeronautics Administ ra t ion sometimes use a three-layer system wi th stone around the pipe and sand adjacent to the trench walls. The stone and sand are kept separate when p lac ing by vertical s l id ing forms.
Roll ing and tamping of the b a c k f i l l was specified by 38 of the states and federal agencies, although sane states believe that because of the granular nature of the mat e r i a l , l i t t l e advantage i s gained through tamping. Nearly the same division of opinion exists as to whether impervious s o i l should be used to back f i l l the top portion o f the underdrain t rench. T h i r t y - f i v e replies said yes; 18 said no. Nevada and D i v i s i o n seven o f the Bureau o f Publ ic Roads often use grouting or a cement mortar seal to accomplish the purpose. New Mexico spec i f ies a t i g h t A-7 s o i l f o r t h i s top layer . Kansas, and probably some other states, does not use this upper impervious layer i f the trench i s under the pavement but does i f i t i s not covered by the pavement or base course. Several states ( Ind i ana, Kansas, Missouri) and the Bureau o f
S I E V E S I Z E -r ^-WATERWAYS EXPT.' STA. .VICKSBURG I
ARIZONA
COLORADO
CONNECTICUT
DELAWARE
I N D I A N A
KENTUCKY
MARYLAND
MISSOURI
NEW JERSEY
T E X A S
VIRGINIA
WEST VIRGINIA
WASHINGTON
WISCONSIN
W Y O M I N G
D I A M E T E R IN MM
104-2 1950 P E R C E N T A G E S AT RIGHT END OF A B A N D ARE
P E R C E N T A G E S PASSING SIEVE OPPOSITE END OF B A N D
Figure 2. Gradation of Backf i l l Materials in 1942 and 1950. See Table C for Details of 1950 Gradation.
Reclamation include a clause i n t h e i r specifications requiring that the b a c k f i l l be removed and cleaned i f clogged by so i l washed into the trench by rains. Most answers did not indicate this to be a problem.
Most states use a trench pay-width of about the pipe diameter plus 8 to 16 i n . or about 2 f t . ; however, the range i s from E)+6 i n . to I>t-30 i n . Utah pays fo r backf i l l i n g widths up to 36 i n . for 6-in. pipe. Actual widths may be greater than these pay-widths, depending on the method o f trench excavation. Previous f i l Z Under Pavement (Questions 31, 32, 33) - Standard practice for 21 of the states i s to extend the granular sub-base for f u l l width of shoulders. Michigan even specifies from di tch bottom to di tch bottom. Connecticut, Texas, and Utah extend the subbase beyond the shoulder to the side slopes. Indiana and Missouri use f u l l width subbases with open-graded granular material but extend densely graded subbases only 1 f t . beyond the pavement edge.
Division Five (North) of the BPR uses a shoulder-to-shoulder subbase for bituminous cons t ruc t ion but extends i t only 1 f t . beyond the edge o f concrete pavement. I l l i n o i s , Kansas, Minnesota, and Ohio use as a standard the width o f the pavement plus a minimum o f 1 or 2 f t . , but l i k e several states, Ohio says that t h i s d i s tance i s "generally to porous b a c k f i l l o f underdrain, 2 f t . from pavement." Standard procedure i n a i rpo r t construction as reported by the Corps of Engineers i s to extend the granular material to a distance of from 3 to 5 f t . beyond the pavement.
Bleeders to provide drainage fo r granular subbases are i n l i t t l e favor. Except fo r seven states, a l l repl ies state that the subbase i s carried out continuously to the underdrain trench or di tch.
Hie variat ion i n the to ta l thickness of pavement courses plus subbase i n earth and rock cuts i n the various states i s quite large and not very reveal ing. Probably some co r r e l a t i on could be found between th i s thickness and other factors such as so i l type, f r o s t penetration, climate, or t r a f f i c . Such a corre la t ion i s probably complex and certainly not evident from the available f igures. One interes t ing relat ionship between pavement thickness and
the geology o f a s tate seems to e x i s t , although the f igures are not conclusive. Western states which have large areas of r e l a t i v e l y f l a t - l y i n g sedimentary rocks often use a greater total thickness of base and subbase i n rock cuts than i n ear th cuts, while those states largely underlain by massive igneous and metamorphic rocks o f t e n use the th icker subbase i n earbh cuts. I t i s suggested that this difference in practice may result from the differences in subsurface moisture conditions associated with the two types of rock.
Vertical 5and Drainage Wells "(Qiestions 3i to 38) - Cal i fornia , (jonnecticut. New Jersey, Missouri, Washington, the Bureau of Reclamation, the Army Engineers, and the CAA report the use of vertical sand drains. The i r use was repor ted by C a l i f o r n i a , Oregon, and Wisconsin i n 1942. Missouri repor ts t h e i r use some 25 years ago i n swamp areas, apparently for the purpose of draining swamp water i n to an underground permeable zone, but the other agencies are reporting recent installations for pressure r e l i e f i n hastening f i l l settlement. A l l agencies report beneficial results.
California reports very rapid settlement of the f i l l with this method—up to 15 f t . o f sett lement dur ing cons t ruc t ion w i t h negl igible settlement a f t e r construction. Washington obtained rapid settlement and was enabled to complete construct ion of f i n a l pavement immediately. Connecticut has completed three projects and reports settlements to be 10 or 15 times as rapid as without the wells; savings varied from $15,000 to $90,000 per project, on projects ranging from small sections of town-aid road to 1,000 f t . sections of expressways. New Jersey's projects are numerous but not completed. The Army Engineers reported their use under dikes; on a dam project the wells saved $100,000 and several months' time. The CAA reported the i r use i n two regions; on one, a i rpor t settlements i n a large experimental area were s l i g h t l y more rapid when the wells were 8 and 11 f t . on centers than when 14 f t . on centers. The compressible mater ia l was s o f t organic s i l t , 60 f t . t h i ck . The appl ica t ion of s o i l mechanics using undisturbed samples i s recommended as essential by a l l those who have had experience with the method.
10
T A B L E A QUESTIONNAIRE ON PRESENT PRACTICE IN SUBSURFACE DRAINAGE
This questionnaire i s sponsored by the Committee on Subsurface Drainage, Department of Soi ls Investigations, Highway Research Board. I t I S intended to record the present pract ice and also the progress since the ear l i er questionnaire on this subject, reported by Levi Muir in the 1942 Proceedings of the Highway Research Board. Re ferr ing brief ly to the latter maybe helpful when answering the questions below. Note that the questions deal with new construction and also with new insta l la t ions for maintenance purposes. Sketches with adequate dimensions are very desirable. Remarks regarding the adequacy or inadequacy of old practices are welcome, of course, part icularly where they i l l u s trate the benefits of progress in subsurface drainage.
1. What types of failures i n subsurface drains have you had; what are their causes^
2. What types of pavement fa i lures due to inadequate or f au l ty subsurface drains have you had; what are their causes^
3. What c r i t e r i a do you use i n determining i f subsurface drainage w i l l help stabil ize the subgrade
4. Is additional base or subbase subs t i tu t ed for subsurface drainage i n so i l s of high capi l lar i ty?
5. Is a single pipe used to carry both surface and subsurface water ' I f so, i s bottom half of pipe sealed''
6. When do you use an underdrain i n stead of a deep d i t c h '
7. Are you conscious of using the i n formation contained i n various ar t ic les i n H.R.B. Proceedings, such as: Porter, Vert i c a l Sand Drains (1938); Russell and Spang-l e r . Energy (incept (1941), Muir, Present Practice i n Drainage (1942); McClelland, Large Scale Mddel Studies (1943); Izzard, Rational Approach (1944); McClelland and Gregg, Methods of Analysis (1944); Keene, Underdrain Practice (1944); Spangler, Sub-grade Moisture Control (1945); Lane and Washburn,. Capi l lar i ty Tests (1946); Krynine, Capillary Flow (1946).
8. What type, i f any, of f i e l d or laboratory research i n subsurface drainage are you conducting?
9. In what respects has your underdrain practice improved since the 1942 questionn a i r e ' (Reported by Muir i n 1942 H.R.B. Proceedings).
10. (Oh new construction): What details o f underdrains, such vas pipe length and depth, kind of b a c k f i l l , e tc . , cannot be completely obtained from your soi l surveys'
TYPE AND LOCATION OF PIPE OR DITCH
11. Check the types of underdrains you use: Perforated Open-Joint Corrugated metal Reinforced Concrete Porous-wall concrete T i le Skip Other
12. I f per fora ted , are holes up or down' Do size and spacing of holes conform to the latest (1948) AASHO recomnendations'
13. How are j o i n t s ins ta l led i n open-j o i n t pipe?
14. What diameter(s) of pipe do you use, where only subsurface water i s carried'
15. What i s usual depth of pipe invert or bottom of ditch below pavement surface'
16. What determines this depth' 17. I s t h i s depth var ied , and why? 18. Are you often handicapped by lack
of a low outlet point nearby' 19. Do out le ts remain open or become
plugged' 20. What i s depth of f ros t for a ' W -
mal " winter where area i s kept bare by snow removal' For a severe winter?
21. What i s usual horizontal distance from edge of pavement to underdrain pipe? To bottom of deep open d i t c h ' What i s your usual spacing between underdrains at a i r ports '
11
22. Do you of ten have underdrains on both sides of the road' Deep open ditches' Do you use herringbone systems of underdrains'
BACKFILL (FILTER) IN TRENCHES
23. What are the gradations for backf i l l materials' ((jive percent passing.)
24. What soi ls are these various types used f o r '
25. What tests, i f any, are used to determine the a b i l i t y of the backf i l l to prevent the soi l from clogging i t ?
26. Do you use coarser material at the perforat ions and at the open j o i n t s than elsewhere' I f so, how do you place i t '
27. Do you tamp the backf i l l when placing i t ?
28. Are there many cases of clogging due to s o i l being washed in to the trench by ra in before b a c k f i l l i n g i s completed'
29. I s impervious s o i l or other mat e r i a l used to back f i l l the top portion of underdrain trench to prevent i n f i l t r a t i o n of surface water'
30. How wide i s the trench when backf i l l e d '
PREVIOUS FILL UNDER PAVEMENTS
31. How far beyond edge of pavement i s granular subbase placed'
32. Is the subbase carr ied out continuously to the underdrain trench or ditch or only by bleeders at in te rva l s ' What i s the spacing of bleeders'
33. What I S the usual to ta l thickness of pavement courses plus subbase i n earth cuts ' In rock cuts '
VERTICAL SAND DRAINAGE WELLS
34. Have you i n s t a l l e d any v e r t i c a l sand drainage wells?
35. Were the results beneficial? 36. What were the benef i t s , such as
saving i n cost and i n time to complete the project ' ^
37. What were the approximate rates of settlement'
38. Was applied so i l mechanics, using test results on undisturbed samples, used in determining the design'
39. Additional remarks:
REFtraNCES
1. Muir, Levi, 'Present Practice in the Lrainage of Highways, " Proceedings, Highway Research Board, Vol. 22, 1941.
2. U. S. Dept. o f A g r i c u l t u r e , 1941 Yearbook of Agriculture. Climate and Man. p. 722, U. S. Govt. P r in t ing O f f i c e , Washington, D. C. 1942.
3. Belcher, D. J . ; Gregg, L. E.; Jenkins, D. S.; and Woods, K. B . : The o r i g i n , dist r i b u t i o n , and airphoto i d e n t i f i c a t i o n of United States Soi l s . U. S. Dept. of Commerce, C i v i l Aeronautics Adminis t ra t ion, Technical Development Report No. 52, Washington, D. C , May, 1946.
4. Ke l l ey , James A . : Microchemical examination of so i l solut ions. Bureau o f Public Roads, Vol. 16, p. 77-89, July, 1935.
5. Horner, S. E . , and McNeal, J . D. , "Applications of (jeology to Highway Engineering, " Applied (leology. Quarterly of the Q>lorado School of Mines, Vol. 45 • Number IB, p. 155-186, January, 1950.
6. McQelland, T. B. , 'Large-scale Model Studies of Highway Subdrainage, " Proceedings, Highway Research Board, Vol. 23, 1943.
7. Investigation of F i l t e r Requirements for Underdrains, U. S. Watetways Experiment Stat ion, Vicksburg, Miss. , Technical Memorandum No. 183-1, Nov. 1. 1941.
8. Bleck, A. T.: Pavenents and influences a f f ec t ing or determining the i r performance. Highway Research Board Bul le t in No. 20, pp. 21-69, Sept., 1949.
9. Keene, P h i l i p , 'Underdrain Practice of the Connecticut Highway Dept., " Proceedings, Highway Research Board. Vol. 24, 1944.
10. Saad, M. A., 'Expedient Methods for S t a b i l i z i n g Swamps, " Proceedings,Highway Research Board, Vol. 30, 1950.
11. '^bsurface Drainage Investigation, 1945-46", Comprehensive Report and four Appendices, New England Divis ion, (2orps of Engrs., U. S. Amy, Boston, Mass. Appendix I - Report on Theoretical Analyses of Drainage of Base Courses, L. A. Pipes. Appendix I I -Report on Viscous F l u i d Model Tes t s . Appendix Ill-Report of Field Investigatitms. Appendix IV - fieport on Fu l l Scale F ie ld Drainage Tests.
12. Casagrande, A. , and Shannon, W. L . , 'Base Course Drainage for Airport Pavements", Proceedings, Am. Soc. dril Ehgrs., Separate No. 75, June 1951.
T A B L E B
I?
I l l i i J l l l l l l l i J l l l l i i i i l l i l l l l l l l i l l l i l l ^ S i i i
u . s Eng.
X X X X X X X X
1. FAILURES IN S.S.D. AND CAUSES Clogging b a c l i f i l J and p ipe Crushing pipe
Roots i n pipe O u t l e t s clogged
Poor c o n s t r u c t i o n Impervious s o l ]
Shal lo> S S.O None r e c e n t l y Lendsl ides
2 PAVEMENT FAILURE AND CAUSES Breakup, pumping, f r o s t se t . Wet Subgrade
C a p i l l a r y e s te r Poor or no S.S.D.
Set t lement e t S.S.D. Landsl ides
3 CRITERIA - w i l l S.S<D. he lp S.G ObserTstions and experience X X S o i l surrey
X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X X X
X X X
X X X
X
X X X X
X X
X X
X X X X X X X X X X X X X X
X X X X X X X X X X X X X X X
X X X X X X
X X X X X
X X X X X X X X X
Depth G.W T. Depth f r o s t
S o i l type Topography
4. ADD. SUBBASE SUBST FOB S.S.D Yes No Added but not s u b s t i t .
X X X X X X
X X X X
X X X X
X X X X X X
X X X X
X X X X X
X X X X X X X
X X X X X X X X X
X X
X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X X X X X X X
II ̂ 1 ^1 ssl X X X X
s V < a: B
aa (J
6 - o i - S j
a J =£ =0
ii II
X X X X
X X X
X X
X X
X X
X
X X
If g
X X
i l l s • -
p
? a ff EP ? r* n r*
f J?? s » 1 § § i » Q half
halt half
i s
pipe pipe pipe
!! 3 S i lied L
sea rasio
cn
| S !
s o
X X Alabama X Aritona X Arkansas X Cal 1 fomia X Colorado
X Connecucut X Oelovare X Idaho
X I l l i n o i a X Indiana X Kansas
X Kentucky X X Maine
X Maryland X X Massachusetts X X Michigan
X Minnesota X Missouri X Nevada
X New Hampshire X X New Jersey
X New hfexico X New York X North Carolina X North Dakota
X Chio X Oklahooia
X Oregon X X Pbnnsylvania X X Rhode Island
X South Carolina X South Dbkota
X Texas X Uuh
X VeriDont Virginia
X Washington X West Virginia
X Wisconsin X Wyoning X E. P. F.*
B P.R Dins ion 5 X North
B.P H Division 7 X San Fr. Califorme
X X Washington U S X Boston Eng
B.P.R. Division 8 Portland, Oregon
B.P R Division 9 X Denver, Colorado
X X CA.A. B P.R Division 10 Juneau, Alaska
U.S.A. C of Engr. X L. A , California
U S A . C of Engr. X San Francisco, Cal
U S A . C of Engr. Portland, Oregon
X U.S.A. C of &)gr. Cincinnati, Ohio
Bureau of ReclanaUon Denver, Colorado
£ T
g
9 S.S.D. MBdVEMENT Srao; 1 9 « Graded and-or f iner back f i l l Deeper or better location More S.S.D. Uae perf A.CCM.P.
No Gombination drain No frencb drains Ful l Width sub-baae More Boll surreys None
i i l J l l L l i i l , ! I l l -
r- a CO ui (D 3 (S 6 11
dHaiiiJsjji i iJii i i i i i i i ij iJ i i iu i i i iJ is si j i i i i i i imimm X X X X X X X X X X X X X X X X X X X
X X X X X X X
X
X X
X X X X X x x x x x x x X X
X X
10 DETAILS NOT (EmraS BY SmVEX Depth Length Dlam pipe Springs or pockets Final detaila
. Need for S S.D. None
11. UNDEHOVUN USQ) Corr. metal - perf. Concrete - perf. Concrete open j o i n t Poroua concrete
T i l e - perf. T i l e - open j o i n t Skip Othera
X X
X X X X
X X X X X X
X X
X
X X
X X
X X X X X X X X
X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X X X X
X X X X X X X X X X X X X X X X X X X X X
X X X X X X X X X X X
X X X X X X X X X X X
X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X X X X X X X
X X X
X X
X X X
X X
X X
X X X X
X X
X
12 FIFE FEBFGRATICKS IP Down Like 1948 AA3D
13. joims CF <XB>-xm em Burlap Tar paper B and S or collar Butt only Clipa or lugs
14- DIAM. PIPE, S.S. WflH) OILY 4 inchea 6 inchea 8 inches
10 inches 12 inchea 15 inches 18 inchea 24 inchea
« 1
l l s l J s l l l l l l l l l l l l i i J i l l l i l l l l l l i l l H i ^ I
• g o d i-S-S
X X X x x x x x x x x x x x x x x x x x x x x x
x x x x x x x x x x x x x x x x x x x x x x
X X X X X X X
X X X X X X X X X
X X X X
X X
X X X X XX X X X X
X X
X X
X X X X
X X X
X X X X
X X X X X X X
X X X
X X X X X X X X X X X X X X X X X X X
X X X X X X X X X X
X X X
X X X X X
X X X X X
S<3
( c ? ai
s it
X X X X X X
X X X X X X X X X
X No
X X X
X
X X X X X
15 CtFIH, Pire CB DITCH IK inches 2 inches ^ inches 3 inches 4 inches 5 inches 6 inches 7 inches Varisble
X X X X X
X X X
X X
X X
X X X X X X X X XX X X X X
X
X X X X X
X
16. WHAT EEIEBMINES DEPIH Ground vater Depth of f ros t
Soil type Depth of outlet Vilteel Loads Local condition Specificauons
17 DEFIH V̂ VUES AND WY Yes - to ground water Yes - i f outlet permits Yes - see quesUon above No
H U
3 J i S a a J a L l l i l j i i j i i •Si •4h 1̂ , . .u. OS 'S od l a °i£
g .,5 a;5 -s U^i-s
X X X X X
X X X X
X X X X
X X X
X X X X X X X X X X
X X X
X X X
X X X X X X X X
X X X X X X X X X X X X
X X
X X X X X X X X X X X
X X X X X X X X X X
X X X X X
X X
X X
18 OFun ua UJH cuiur Yes Otcasionajly No
X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X X X X X X X X
X X
19 OUOEIS REMAIN OfK (B CET FUUQGEl) Open Usiuilly open Plugged
20 CEPIH OF FKBr-rD»1AL WMHl
a toot 1 foot
IX feet 2 feet
2i feet
X X X X X X X X X X X X
X X X X X X
X X X X X X X X X X X X X XX X X X X
X X X
X X X X X X X X X X X X
X X X X
X
C X X X X X X X
X X X X
X X X X X X X X X X
X X X
X X
X X X X X
X X
X X X X X
X X X X X X X X X X X X
1-8 S C I I I ? 1i \6&
! a g s g a ,
Dtpth of frost-nonnal winter (cdnt.) 3 feet 4 feet 5 feet 6 feet
5 i l 3 S l 5 3 S l | | | | | | | | | i l l l l | g S ^ l l l l l l l > - | l l l ^
S 3
X X X X X X
X X X
X X X X X
X X X
t &
X X X X
« bo O C CT» O
s i
I &1& .- <s -
O n • s i < t? < s It
A
21 EBGE PAVT TO PIPE q, 1 foot 2 feet 3 feet 4 feet 6 feet 8 feet 10 feet Variable
X X
X X X X
X X X X
X X X X X X
X X
X
X X
ms. PAV'T TO (PEN Di rm 10 feet 15 feet 18 feet 20 feet 25 feet 30 feet 40 feet SO feet
100 feet Variable
X X X X
X X X X
X
X X
X X
X X X X X
22. U. D. OFUN Ol BOIH SUES Yes
Occasionally
No
X X X X X XX X X
X X X X
X X X X X X X X X X
X X
S B S 5 5 S B P P P § B 3 S s i 5 S | S
X X X X X Alabama
M X X X X Arizona X X X X X Arkansas
X X X X X California X X X X X Colorado X X X X X Connecticut X X X X X Dblamre
X X X X X Idaho X X X X I l l i n o i a
X X X X X Indiana X X X X Kansas
X X X Kentucky X X X X Maine
X X X X X Maryland X X X X X X Massachusetts X X X X X Michigan
X X X X Minnesota X X X X Missouri
X X X X X Nevada X X X X X X New Hanpshire
X X X X X X New Jersey X X X X X New Mexico X X X X X X Ne« York X X X X North Carolina X X X X X North [Uiota
X X X X Chio X X X X X Gklahona
X X X X X Oregon X X X X X Penusylvania
X X X X X Rhode Island X X X X X South Carolina
X X X X X South Dakota X X X X X Texas
X X X X X UUih X X X X X Vermont
X X X X X Virginia X X X X X WashingtCD
X X X X X West Virginia X X X X X Wisconsin
X X X X X Wyoeang
X X X X E.P.F • B.P R Dlnsion 5
X X X X X North aP.R. DiTisioa 7
X X X X X San Fr Ce l i fomi Washington U.S
Boston Eng. B.P,R. Division 8 Portland, Oregon
B.P.R. DiTision 9 Denier, Colorado
aA.A. B.P.B. DiTif ico 10 Juneau, Alaska
U S.A. C of Engr. L A . , California
U S.A. a of Engr. <San Francisco, Cal.
U S.A. C. of Engr. Portland, Ongm
V S.A. C. of Engr. Cincinnau, Ohio
Bureau of Heclamaucn Denver, Colorado
8 T
g
31. SUB-BASE BEYCTO EDGE PAVT
To u. d. or ditch X X X X X ' X X Through shoulder X X X X X X X X X X X X X X X X X X X X X X 1 f t . mnimuD X X X X X X X X 2 f t . minimum X 5 f t . minimum
3 2 . a £ B A S E CAnUEDGUT
X X X X
Contin. to u.d or ditch X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Bleeders to u.d. or ditch X X X X X X X X A A A X
33 PAVT. + SLEBASE IN EABIH 2 i n 6 i n . X X X X X X X X X
X X X X X X X X X X X X X X
X X X
X X X X X X X X X
9 i n . X X X X X X X X X X 10 i n . X X X X X X X X X X X X 12 i n . X X X X X X X X X X X X X X X X X X X X X X X X X 15 in X X X X X X X X X X X X X X X X X X X X X X 18 u , . X X X X X X X X X X X X X X X X X X X X X 19 i n . X X X X X X X X X X X 21 i n . X X X X X X X X X X X X X X X X X X X X 22 i n . X X X X X X X X X X 24 i „ X X X X X X X X X X X X 2711. X X X X X X X 30 i n . X X X 32 i n . X X Variable X X X X X X X X
34,INSKLL. WOT. SAIWHIS w v y y Yes X X X X X X X X X No X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
35 »HE BESUIS BENEnOAL „ w v v Yes X X X X X X X X X
36.SOn, WXWNICS USE) JN EESICN „ v v v v v v Yes X X X X X X X X X X
20
T A B L E C B A C K F I L L SPECIFICATIONS (QUESTIONS 23,24,25,26)
IN WHAT SOILS PERCCNTAGE OF MATERIAL PASSINO SIEVE SIZE
STATE
H I G H W A Y R E S E A R C H B O A R D B U L L E T I N S
1 Silicate of Soda as a Soil Stabilizing Agent (1946) 21 pp. $ . 15 2 An Analysis of General State Enabling Legislation Dealing with Automobile
Parking Facilities (1947) 110 pp. (out of print) 3 Report of Committee on Highway Organization and Administration (1947)23 pp. . 30 4 Report of Committee on Land Acquisition and Control of Highway Access
and Adjacent Areas (1947) 42 pp. . 45 13 Report of Committee on Compaction of Subgrades and Embankments (1947) 23 pp.. 30 6 Report of Committee on Uses of Highway Planning Survey Data (1947) 40 pp. . 45 7 An Analysis of State Enabling Legislation of Special and Local Character
Dealing with Automobile Parking Facilities (1947) 30 pp. . 30 8 Design of Flexible Pavements Using the Triaxial Compression Test -
Kansas Method (1947) 63 pp. . 75 9 Salary and Wage Practices of State Highway Departments (1947) 51 pp. . 60
10 Report of Committee on Land Acquisition and Control of Highway Access and Adjacent Areas (1948) 46 pp. . 60
11 The Polarized Headlight System (1948) 40 pp. . 60 12 Highway Finance (1948) 69 pp. . 75 13 The Appraisal of Terrain Conditions for Highway Engineering Purposes
(1948) 99 pp. 1. 50 14 Soil Committee Reports and Special Papers (1948) 42 pp. . 60 15 Parking, Committee Report and Three Papers (1948) 31 pp. . 60 16 Expressways, Committee Report and Three Papers (1948) 21 pp. . 45 17 Highway Planning (1948) 45 pp. . 60 18 Land Acquisition and Control of Highway Access and Adjacent Areas, Report
of Committee and Four Papers (1949) 44 pp. . 60 19 Parking (1949) 78 pp. . 90 20 Pavement Performance (1949) 74 pp. . 90 21 Maintenance Costs (1949) 20 pp. . 15 22 Engineering Use of Agricultural Soil Maps (1949) 128 pp. 1. 80 23 Compaction of Soils, Two Papers (1949) 17 pp. . 15 24 Zoning for Parking Facilities (1950) 161 pp. 3. 00 25 Controlled Access E:q)ressways in Urban Areas (1950) 45 pp. . 60 26 The Truck Weight Problem in Highway Transportation (1950) 130 pp. 1. 20 27 Road Surface Properties, Report of Committee and Paper on Rubber in
Bituminous Pavements (1950) 27 pp. . 45 28 Soil Exploration and Mapping (1950) 124 pp. 1. 50 29 Maintenance Costs (1950) 23 pp. . 30 30 Progress in Roadside Protection (1951) 54 pp. . 75 31 Highway Planning (1950) 26 pp. . 45 32 One-Way Streets (1950) 39 pp. . 60 33 Use of Parking Meter Revenues (1951) 30 pp. . 60 34 Reflectors and Night Visibility (1951) 57 pp. . 90 35 Highways with a Narrow Median (1951) 98 pp. 1.50 36 Pavement Marking (1951) 32 pp. . 45 37 Roughness and Skid Resistance (1951) 59 pp. . 90 38 Land Acquisition and Control of Adjacent Areas (1951) 82 pp. 1. 20 39 Precasting Bridges and Structures (1951) 20 pp. . 45 40 Load Carrying Capacity of Roads as Affected by Frost Action (1951) 42 pp. . 75 41 Traffic Surveys by Post Cards (1951) 32 pp. . 60 42 Soil Compaction (1951) 23 pp. . 45 43 Studies in Night Visibility (1951) 56 pp. . 90 44 Volcanic Ash and Laterite Soils in Highway Construction (1951) 32 pp. . 60 45 Subsurface Drainage (1951) 23 pp. . 45
N A T I O N A L R E S E A R C H C O U N C I L
The National Academy of Sciences is a private organization of eminent American Scientists, chartered under a special act of Congress in 1863 to "investigate, examine, experiment, and report on any subject of science or art. " The Academy maintains the National Research Council as its operating agency.
The Council, organized with the cooperation of the scientific and technical societies of America, enjoys the voluntary services of more than 2600 scientists making up over 400 standing committees, boards, and panels in all fields of the natural sciences; its membership includes representatives of business and industry. The Council provides advisory and administrative services for research, and attempts to stimulate and coordinate research effort.
DIVISION OF E N G I N E E R I N G AND I N D U S T R I A L R E S E A R C H
The National Research Council operates through eight divisions covering fundamental and applied natural sciences, as well as matters of international relations in scientific research. The Division of Engineering and Industrial Research is concerned with the stimulation and correlation of research in a wide variety of fields in engineering and the applied sciences.
EXECUTIVE COMMITTEE - C. RICHARD SODERBERG, Chairman; WM. R. HAINSWORTH, Vice Chairman; FREDERICK M. F E I K E R , T. H. MacDONALD, PAUL D. FOOTE. EXECUTIVE SECRETARY - LOUIS JORDAN.
H I G H W A Y R E S E A R C H BOARD
The Highway Research Board is organized under the auspices of the Division of Engineeringandlndustrial Research of the National Research Council . Its purpose is to provide a national clearing house for highway research activities and information. The membership consists of 42 technical, educational, industrial, and governmental organizations of national scope. Associates of the Board are firms, corporations, and individuals who are interested in highway research and who desire to further its work.
The purposes of the Board are: "To encourage research and to provide a national clearing house and correlation service for research activities and information on highway administration and technology, by means of: (1) a forum for presentation and discussion of research papers and reports; (2) committees to suggest and plan research work and to correlate and evaluate results; (3) dissemination of useful information and (4) liaison and cooperative services."