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HomeMy WebLinkAbout03-28-1974 Dinner Meeting (2)Commission agreed to have dinner meeting with realtors and Developers on Thursday, Maroh 28, 1974 from 6:00 P.M. to 9:00 P.M. at the Firemen's Hal1.Mr. Boa and Mr. Field to be in oharge of Publiolty and Invitations, Mr, John Parker and Mr. Ceoll Pitman In oharge of Program and Mr, Kirk, Mr. Billie, Dr. Frederiok and Mr. Gibson to be in oharge of the dinner. , i I� i 4 I _ 1 1, r l 1� i • pry,., a Maroh s, 1974 Alabama Beal $eiate Qonuiselan Montgomery; Alabama Gentlemen t ' This is toyadvise that 80$ North Seotion Street in the City Limits of Fairhope, Alabama is Zoned B-2g Business. Very truly yours, CITY OF FAIHSOPS City Clerk Population Projections Almost all major planning decisions have as their base an analysis and projection of population. Such techniques are em- ployed as measures of the size and density of the various groups. within the regional or municipal population. They determine the level of demand for facilities and serve as an indices to assist in the resolution of most regional and'community problems. Generally, no other local agency provides projection data in a way that is useful for these purposes; accordingly, the respon- sibility falls to the local planning commission. The substantial importance of population projections to all aspects of planning reflects the need to develop projections which are sufficiently detailed to serve as a basis for the design of local community facilities and services. Any method employed to project population will result in a projection that must be used with caution. The projections in this report are based extrapolation of current trends. They do not reflect probable deviations from traditional growth patterns. Unfortunately, the findings of any study which probes the future more than five or ten years ahead are subject to numerous uncer- tainties. Therefore, the projections in the following can be considered to represent areas of opportunity rather than precise levels of achievement. Performance outside the projected para- meters cannot be discounted. Thus, periodic review is necessary to compare projections with actual results. 1 .•..,- - r tq { 264 A�1SHO—GEOMETRIC HIGHWAY DESIGN —URBAN AT -GRADE EXPRESSWAYS Z6S Ili +I . • t � ' it t • ; : + half or a full block are needed. Where a half -block width is to be taken will be preferable, both for the avoidance of remnants of land and from 9 i h, standpoint of cost, to take the whole depth of a row of lots one ✓ap�og % ; _ s' a of an existing street rather than half portions of the lots opposite x _ " �- iro tapes. The method of utilizing a half block for the dev pment of a high y is demonstrated diagrammatically in figure F-6. n each of the three p is the upper diagram shows the cross section oft a block involved I ; 1 41=1121�' ;i W ' before co truction and the lower after construction. w'a' o ' ; W Q . An expres way with two frontage roads is show in figure F-6a. The W. i_ z existing street n the right is retained (altered if ecessary) and a new w tl Cr ;— �� N fronta a road I troduced adjacent to the rem ning property. Figure ?''+ I; (. W w F•6b shows the c e in wide blocks where the th of a tier of lots on ' 3 ` I „'o •* h; w ►- ' one side of a stree 's greater than required or the section. The usable , I ! 'v . h h g q I °� �.• w width of the balance left in private owner6hip for redevelopment. Such I- remnants, when situate near business districts, can be used to advantage I'� j for development of park g facilities. Figure F 5c shows an expressway I. h with one frontage road in a narrow block whers one row of lots is not wide enough for a highway ith two frontage roads and the acquisition of NN.:, _ �� Q M a full block is not feasible. his necessitates the purchase of all access � ��•;- f 3 o rights and the use of cul-de•sa or dead -ends on one side of the arterial on those streets not carried acro s the facility. The single frontage street +n does not necessarily imply that i must be operated two-way. It can be iit ! n! n 3 �'' operated to form a one-way pair wi the other existing street. I ; •N W d ,s , I�l�. i5 w U_ a, Figure F-7a is a cross 5Section of a expressway on a block -wide strip ' , • ' �; i a i� where the blocks are narrow or where ture grade separations and ramps are envisioned. The two flanking street are retained as frontage roads : ji;i ((• Fand the area within utilized for the thro h facility. Figure F-7b shows (' h a an expresswayon relatively narrow right- wa constructed in the middle fl' •tr. o,: o Y g Y' of a wide block, retaining the development obi the land for development on f _ both sides of existing or platted parallel stree\ar The outer roads are local a " o streets rather than frontage roads. Such an ,ngement is applicable in W e0 residential areas where unusually deep lots are available or in districts �. WSW H �.,� _ yet undeveloped, as discussed under Expresswaysithout Adjacent Front. 1 i o h_ {. Q age Roads. ;Where an alley is eliminated the se ice provided thereon z must be provided on adjacent streets. ' A INTERSECTIONS � F; I ' ' y6no�y1 t i 3 Design Considerations ! I ' .. uorlaodar ,d�„oOn at -grade expressways the spacing, layout., and tra ,ee trol de i•,;:,- vices of at -grade intersections determine to a considerablree the ; efficiency and safety for the whole of the arterial highwaminor (,, t cross streets should be terminated. The location and design arterialhighway involve a thorough analysis of the street systemhe pat- ; I•;1).t tern and density of traffic thereon in order to determine the a ect of -- terminating some streets and concentrating cross, turning, and ecess :•I.', .w oa traffic on other streets. The desirable distance between streets hick continue across and have access to or from an arterial facility v ies. �; In business districts it may be necessary to keep nearly every cI ss 298 AASHO—GEOMETRIC HIGHWAY RESIGN 00 ssings at grade with the one-way pavements are g atly simplified in de ' n and o\ea eration. Accident potential is gener y reduced and capacitntersections is increased. Moreover, opera 'on on widely sep- arated ays provides the maximum in driver comf t. Strain is lessened by largloafing the view and influence of oppo ng traffic. Substantial reducti'mination of headlight glare at nigh especially helpful in easing t sion and in minimizing hazards /resulting therefrom. Ifhs o appreciable length have roa ways separated so widely that eadwa cannot be seen from the �r her, drivers may develop a sense og on a wo-way instead of a o -way roadway and hesitate to pass slving ve 'cles. This is not h ardous but decreases somewhat the utithe divid highway. This n be alleviated by an occasional open vtween the o roadways. Chapter V1 ' CONTROLLED ACCESS HIGHWAYS (Full and Partial) INTRODUCTION Control of access is the condition where the right of abutting owners to access in connection with a highway is fully or partially controlled by public' authority. Full control of access means that the authority is exercised to give preference to through traffic by providing access connections with selected public roads only and by prohibiting crossingg at grade or direct private driveway connections. Partial control of access means that the authority to control access is exercised to give preference to through traffic to a degree that, in addition to access connections with selected public roads, there may be some crossings at grade and some private driveway connections. General discussion herein applies to both full and partial control of access. It is not feasible in this policy to discuss the many operational and eco- nomic advantages resulting from control of access nor to show the legal and administrative measures necessary to obtain it. There is an abundance of published material on these subjects; see list of references at end of chapter. The principal advantages of control of access are the preservation of the as -built capacity of the highway and the improved safety to all highway users. Being a condition rather than a design feature, control of access is dis- cussed herein to indicate the design considerations necessary to effect that li condition, and to describe the design features that distinguish the fully controlled access highway from that with partial or no access control. Con- trolled access highways nearly always are high type highways with modern, r flowing alinement and profile and reasonably ample cross section elements. S — Fully controlled access highways, either 2-lane or divided highways, ad- ditionally have grade separation of all crossroads, railroads, etc. and care- fully designed access connections located only at selected points, usually public crossroads. Between these connections, all other entry is barred, either by legal or acquired controls along the right-of-way lines or by t frontage roads. A highway with partial control of access has the same characteristics but includes some intersections at grade of crossroads or carefully selected and predetermined land service connections, It has control; of access along all or most of its length but lacks the, complete grade sep:cation treatment. The principal operational or functional difference between a highway with and one without control of access is in the degree; of interference with through traffic by other vehicles entering, leaving, and crossing the high- way, and by pedestrians. Where there is control of access, entrances and exits are located at points best suited to fit traffic needs and designed to enable; vehicles to enter and leave safely without interfering with through traffic. Vehicles are prevented from entering or leaving elsewhere so that, regardless of the 'type and intensity of development of; the roadside areas, 299 IIt I k,• , 1 tt I 1 , 300 AASHO—GEOMETRIC HIGHWAY DESIGN the capacity of the highway is maintained at a high level and the accident r I hazard is kept low. I Where there is no control of access and roadside businesses develop along the highway, as in suburban areas, interference from the roadside can become a factor of major importance, reducing the capacity of the highway and increasing the accident hazard. As traffic increases, roadside businesses become more profitable and grow in number, thereby further increasing interference and hazard and lowering capacity. Congestion develops and attempts to correct the highway deficiency by widening it are frustrated by the high value of the roadsides, by the very businesses which contributed I y to the unfavorable situation. Highway obsolescence creeps in and authorities ultimately are forced to relocate the highway on new right-of-way. This is a i a costly and unnecessary drain on public resources. Allied to control of access is driveway and roadside control as discussed under Other Elements Affecting Geometric Design in chapter III. Opera- tion on the highway is little affected if entrances are few and far apart, but where they are numerous, particularly those serving commercial es- tablishments, they adversely affect capacity and safety and allowance should s j i be made in design for these effects. .k ,q Access control is generally accomplished either by legally obtaining f rights of access from the abutting property, usually at the time of purchase of right-of-way, or by the use of frontage roads. Where a freeway is developed on new location the cost of access rights is nil since the adjoin- ing property owner has no inherent right of direct access to a highway -. , . that does not exist. This case is separate and distinct from damages result- ing from, say, severance due to construction of the highway. Some State laws may be at variance with the concept of no inherent right of direct access to a highway developed on new location. tI ACCESS CONTROL WITHOUT FRONTAGE ROADS 4.11 *14 9 Rural highways with control of access are not materially different in 1 design from those without control of access when they are remote from cities and not within their influence. Distances between public highway crossings on such highways are great, entrances from adjoining privately- ; i:1 owned land are few, and there is no appreciable development of private businesses along them. The population density of land is low and since distances between homes and places of business are long, travel is in `vehicles and there are few pedestrians. Control of access in such instances might be obtained, to a degree, by means of agreements with adjoining land owners to a limit of only one or two entrances to or crossings of the jlf 1 highway for each farm, and agreements to refrain from developing the land at these entrances for roadside businesses. Design of the cross section j and of other elements in such case is much the same on highways with and without control of access. Controlling access in this manner may not always be feasible or fully effective, in which case other, more positive, �I means of control become necessary. Furthermore, expanding metropolitan areas are continually absorbing miles of highways that were in rural areas • ;, + at the time of construction, and this trend may be expected to continue. Highways located within the influence of urban areas are subject to the + ' undesirable and deteriorating effects of uncontrolled access, particularly CONTROLLED ACCESS HIGHWAYS ? 301 where there is little or no land use control on the industrial, commercial and residential developments on adjacent land areas. Highways in suburban areas are particularly vulnerable. Land is subject to intensive development, as demonstrated by the fact that the suburban -urban type of traffic has had the most rapid and sustained increase of all traffic, categories. This encourages two kinds of roadside businesses: those catering to highway traffic and those serving the adjacent land developments. For example, suburban housing requires commercial establishments to serve it. While there has been an encouraging trend toward integration of housing and local commercial service, the customary procedure is to locate the com- mercial establishments along the highway, particularly; at intersections where roadside interference is most troublesome. The inevitable result is that the highway must serve through traffic, short -haul traffic, local business traffic, mass transit, and pedestrians; consequently it serves no pne type of traffic well. Obsolescence creeps in, capacity drops, l and accidents in- crease in number. Partial control of access, properly exercised by public! authority, limits the number of private driveway connections and crossings at grade to a minimum in order to give preference to through traffic. ''With full control of access there are no private driveway connections. A high degree of partial access control or full control of access generally is feasible without frontage roads when the highway is located on new right-of-way. In ' this case the owners and occupants of adjoining land previously had ac- cess to other public highways, and such access is no} affected by the new highway. Where a land plot remainder is cut off from access which it previously had to a public highway, one or more entrances to the high- way may have to be permitted, or other means of access provided such as a new private road, or a new section of public road,;'or a section of a frontage road. The design of a controlled access highway without frontage roads is not appreciably different from the design of a noncontrolled access -high- way except that fewer lanes may be required because the controlled access highway usually has a higher capacity per lane and hence the required width of roadway may not be as great. In some cases! the high capacity of a 2-lane controlled access highway may be greater than the design volume, whereas the low capacity of a noncontrolled access highway may call for a highway with more than 2 lanes to accommodate the design hourly volume. In the case of multilane highways, the high capacity per lane of a controlled access highway may be sufficient to accommodate the expected traffic volume on a 4-lane section, whereas more lanes i may be required on a noncontrolled access highway because of less capaei'ty per lane. Precise figures are not available and the designer will have to use judg- ment in evaluating the capacity of a highway with partial' control of access or of one with driveway and roadside control. In using tables 11-8, -9, and -10, which show design capacity of 2-lane rural highways for unin- terrupted flow, the designer will have to reduce the hour',y volumes shown to allow for roadside interference, the amount of reduction depending on the number of private entrances and the probable frequency of use. An entrance to a gas station or other quick service business is likely to be used frequently whereas, entrances to one -family home garages are likely to be l i •- 1 1l . h a 302 AASHO—GEOMETRIC HIGHWAY DESIGN used sparingly. The amount of interference is dependent also on the design of highway and entrances, a wide shoulder, liberal turning area, and good sight distance having less interference than a design with a narrow shoulder and poor sight distance, with entrances requiring vehicles to swing wide. Highways with low volumes are little affected by a lack of control of access since entering vehicles will find numerous breaks in traffic and leav- ing vehicles can slow down with little likelihood of delaying or interfering with other vehicles. This does not lessen the advisability of analyzing the effects of roadside entrances on capacity and, after determining capacity, comparing it with design volume. ACCESS CONTROL WITH FRONTAGE ROADS Where control of access is accomplished by frontage roads, the highway consists of a roadway or roadways for through traffic, and frontage roads for local traffic and for access to adjacent land. Frontage roads generally are parallel to the roadways for through traffic and separated from them by the outer separations. Through traffic may be accommodated on a single two-way roadway or on two one-way roadways separated by a median. Where crossroads are numerous and land is developed on each side of the highway, as in urban areas, frontage roads generally are for one-way traffic. In rural and suburban areas, where frontage roads are intermit- tently provided or located on one side only, such roads sometimes are designed for two-way operation. Where there are frontage roads the design of the roadway for through traffic, whether it be a 2-lane two-way roadway or a divided highway with two one-way roadways, is much the same as for a roadway without frontage roads. The cross section is the same except that special consideration is given to the outer separation in view of the presence of frontage roads. The need for a full shoulder adjacent to the through traffic lanes to avoid interference with through traffic by stopped vehicles is just as great on controlled access highways as on highways without access control. The difference is in the use -of the shoulder for parking. There is little tendency to use shoulders along through traffic lanes for other than emer- gency stops when bordered by frontage roads. Where there may be any incentive to use them for parking, such practice should be prohibited because parking is a form of roadside interference and adversely affects through traffic as discussed under the heading of Shoulders in chapter IV. The frontage road is the proper and desirable place to park. Whether space is available there depends upon demand and supply. In rural areas the demand for parking generally is not great except where there is a large concentration of workers, as. at an industrial plant. In this case separate parking areas off the public right -:of -way should be provided. In suburban areas the demand for parking is somewhat greater than in rural areas and can be very great where frontage roads serve commercial establishments. There is an encouraging trend in the provision of off-street parking for commercial areas and some communities require it. The supply of parking spaces on frontage roads rarely is sufficient for demand in commerical areas. In such cases it may be justifiable to make the frontage road wide enough to enable drivers to park on both sides. In most rural areas provision for parking on the side adjacent to the developed property is adequate, particu- 1 CONTROLLED ACCESS HI liWAYs ' F ^003 larly if openings between frontage roads and private; 'driveways are not numerous. The design should provide reasonably convenient crass connections be- tween through traffic lanes and frontage roads. Many highways with partial control of access (expressways at grade) have crossings at grade where they intersect major crossroads. At some of the less important crossroads, the highway may have turning roadways for' entering and leav- ing traffic on one or both sides but crossings are prevented by a continuous median. At such minor crossroad intersections there is an opening in the outer separation between through traffic lanes and frontage road but no opening in the median. Traffic can change between 'through lanes and frontage road at either of these types of intersection:, Interference with through traffic is slight if the outer separation is wide enough for a vehicle to stop clear of both through traffic and traffic on the frontage road. On freeways with frontage roads there are no crossings at grade and major crossroads are carried over or under the through traffic roadways by means of grade separations. Access "generally is provided by way of the frontage roads with appropriate cross connections to the through traffic lanes. ' Controlled access highways with continuous frontage roads on both sides are provided mostly in urban areas but are used also in suburban areas, and to a lesser extent in rural areas. Normally, these frontage roads serve land on one side only. Their design is t bout the same and their cost no greater when they serve land on both sides. This can be accomplished by locating the parallel local road some distance, say a little more than the customary depth of lot, from the through traffic lanes and leaving the land between the two facilities in private ownership. With such an arrangement property owners have full right of access to the local road and no right of access to the through traffic lanes. The resulting ar- rangement is a controlled access highway without frontage roads but bor- dered by the rear boundaries of the land facing the_paiailel local roads. Reference is made to the AASHO Guide for the Application and Design of Frontage Roads on the National System of Interstate and Defense Highways, 1962, for additional details. The principles stated therein on the use of frontage roads are applicable on all high type highways. RIGHT-OF-WAY In the matter of right-of-way the control or noncontrol of access may be a major factor. The initial design may be the same.regardless of access . control, but without access control allowance should be made for ob- solescence due to decreasing capacity by acquiring sufficient right-of-way to provide for widening or the later addition of frontage roads to serve adjacent property, whereby the high capacity of the through traffic lanes may be maintained. Wide rights -of -way decrease interference from ad- jacent property and provide for more freedom of movement. With control df access the retention of the capacity of the initial design is assured and the right-of-way need not be any wider than for the initial development or to allow for widening due to expected increase in traffic volume. No additional right-of-way is needed, as it is in the case of noncontrolled 304 AASHO-GEOMETRIC HIGHWAY DESIGN access highways where it will be needed for pavement widening to compen- sate for reduction in capacity. CONTROL OF ACCESS AT INTERCHANGES Essential parts of highways with full control of access are the inter- changes. While the crossroad terminal area of an interchange ramp might logically be considered a physical part of the crossroad rather than of the freeway, in the full control of access sense the whole of all ramps should be completely within the control of access limits. Ramps are relatively short roadways nearly always having curving alinement and rolling profile. Driver attention necessarily is directed to guide and warning signs on or in the ramp area. Each ramp, therefore, must be kept free of any inter- mediate roadway connections in order to insure the planned safety and free flow of traffic on it. The direct and simple way is to provide control of access along each ramp, either by legal acquisition or outer frontage roads. At the crossroad end of interchange ramps there are decided advantages in the extension of control of access to some extent along the crossroad. As has been stated in the AASHO Plan to Promote Proper Traffic Operation on Crossroads Near Interchanges, 1964, some control steps need to be put into effect to avoid a series of driveways and intersections to serve a concentration of roadside businesses and other industrial and commercial development within a few hundred feet of ramp terminals. Such controls may be effected in several ways, one of which is the extension of control of access for a few hundred feet along the crossroad beyond the ramp terminal. At new interchanges in rural and suburban areas, and in some cases in urban areas, such control of access extension usually can be effected .at nominal cost when it is done as a part of the interchange right-of-way acquisition. At the -other extreme, at some urban interchanges where a series of developments exist with limited setback street frontage on the interchange cross street just beyond the ramp terminals, there may be little possibility of an extension of control of access since it would require removal or major adjustment of the developments themselves. FENCING Fencing along a highway is a means of preventing unwanted and likely hazardous intrusion of animals, people, vehicles, machines, etc., from outside the right-of-way line into the vicinity of moving traffic. In many cases the abutting property owner erects and maintains such a fence and when so satisfactorily accomplished the highway agencies have no need to be concerned with fencing. In other cases the landowner has little or no interest, or perhaps no legal concern, and a fence where needed must be provided as a part of the highway facility. On controlled access highways, drivers travel at high speeds expecting complete protection from all forms of roadside interference. This makes fencing essential as an integral part of the highway wherever there is a potential hazard through encroachment. To the extent that a fence is needed and an appropriate type is not provided and maintained by the abutting landowner, the highway agency should erect and maintain it. All portions of a controlled access highway do not necessarily require fencing �i CONTROLLED ACCESS HIGHWAYS 305 as there are sections where there is little or no warrant for fences. But wherever the safety of freeway operation requires fencing, it should be considered as an essential part of the total highway facility, constructed as a highway item if not otherwise provided. Reference should be made to AASHO Policy on Fencing Controlled Access Highways, 1959, for general principles applicable to the utilization and placement of fences along freeways. _ COST OF ACCESS CONTROL While the initial cost may be high, controlled access highways are economical in the long run. Whereas the highway without access control begins to lose capacity as soon as roadside interference begins (and de- terioration in this regard progresses rapidly with time), the controlled access highway steadily retains its ability to handle traffic. This -results in the noncontrolled access highway becoming obsolete :when it is most needed and in the costly necessity of relocating or constructing a new highway, or both, whereas no such relocation or construction is necessary on a controlled access highway. There are numerous examples of the former, whereas some of the early examples of controlled access highways are just as efficient in handling traffic now as they were when opened to traffic a third of a century ago. i Regarding initial cost, there is a general impression that controlled ' access highways cost considerably more than highways without access control. This may not be so, particularly where the higi.way is located on new right-of-way. The impression probably stems from evaluations of constructing controlled access highways on existing routes, where traffic is heavy, additional right-of-way cost high, and grade separations are required at many crossroads. Where standards are the same the cost of construction, exclusive of cost of right-of-way, is no more with control of access than without it and may be less because no allowance need be made for additional lanes due to expected reduction in capacity and because' some costly details - -can be omitted. Curbs, for example, can -be omitted on -controlled access highways but may be necessary where many direct ;,,,ntrances must be provided. i Right-of-way for controlled access highways generally costs little or no more than right-of-way without access control when th'e area acquired is the same, but the cost of acquiring access rights may b appreciable if an existing highway is being improved to include control of access. In rural areas the added cost is usually small and may be compensated by the smaller width of right-of-way required for controlled at'cess highways. Of course, where frontage roads are needed to control 1,iccess, the cost of both right-of-way and construction is greater than for.an equivalent road without frontage roads, but the type of service between, the two is so dif- ferent that direct comparison is not valid. In addition to the long-range economy in control i'f access and little or no increase and possibly decrease in initial cost, :there is the major economy in benefits to road users. Road users benefit i-;y control of access in two ways: by reduction in cost of motor vehicle operation ,and by re- duction in accidents. The reduction in vehicle operating cost results from operation at a uniform continuous speed as compared to the usual start 306 AASHO—GEOMETRic HIGHWAY DESIGN • CONTROLLED ACCESS HIGjiWAYS '? 307 and stop operation on highways without access control. An important part The reduction in accidents is considerable, particularly, head-on or side - Those classed as "Other types of of the reduction in cost is the saving in time but there also are additional swipe opposite -direction types. accidents collision," consisting principally of single vehicle collisions with fixed intangible benefits to drivers, such as relaxation and lack of strain in driv- in ; ! objects, were exceptional in that this group showed 'a slight increase. g- !Reasons for the actual numerical increase of this group are not available. () Benefits to road users due to accident reduction resulting from control of access are clear and unmistakable, but the dollar value of accident re- ! Angle type collisions and collisions with pedestrians have been almost duction is difficult to measure. In a study 1 in Illinois it was found that eliminated. Collisions with fixed objects and noncollision` types were similar benefits ranged from 0.20 cent per vehicle mile on highways carrying up i to those on existing highways. Control of access does not necessarily imply high volume loads. Access to 5,000 vehicles per day to 0.40 cent per vehicle mile for traffic volumes _ ; is just as valuable on 2-lane roads as on multilane roads and par - of 25,000 or more. Experience shows that the accident rate on controlled access highways generally is one-half that on noncontrolled access highways. control titularly valuable on 2-lane roads with volume near capacity, for which Using Safety Council figures for the year 1963 s it may be shown that since control or noncontrol of access may make the difference between need or However, acceptance of access control and accidents cost about 0.96 cent per vehicle mile a reduction to one-half the no need for wider roads. public relatively higher operating speed may justify divided highways for volumes accident rate saves about 0.48 cent per vehicle mile. The significance of this capacity less than ca acit of 2-lane roads. Control of access Hoes not necessarily �I unit savings can be judged by considering a highway with 10,000 vehicles imply grade separations; they should be used only where traffic conflicts per day. Based on an assumed interest rate of 31/2 percent and 40-year amortization, the accident reduction alone justifies an additional initial justify, just as on any other highway, although driver' expectation of no expenditure of about $350,000 per mile to obtain full control of access. cross traffic, the desirability of relaxed driving and system uniformity may justified economically. The y 'I The reduction in accidents is less for partial control but it would be diffi- justify grade separations where not strictly economy of control of access, both in cost and savings to road cult to evaluate the effect of control of access alone, since other elements principal lies in the elimination of roadside interference. of design that normally are associated with highways that have full control t users, of access are also important considerations. Partial control of access highways in suburban areas have shown fairly high accident experience. A comparison may be made of types of accidents on conventional high- ways versus freeways. A study 3 of accidents on the Interstate system com- pared accidents on the existing highways within the Interstate system corridors which formerly carried the greatest proportion of the Interstate traffic before opening the Interstate section. Approximately 80 percent of the highways studied were rural on which results by type of collision were as follows: Type of collision Accidents per 100 million vehicle miles Existing Interstate Ratios, existing or accident highways system highways "before" "before" highways Interstate system Head-on or sideswipe, opposite direction 34 1 34 to 1 Angle 32 4 8 to 1 Collision with pedestrian 4 1 4 to 1 Rear -end or sideswipe, same direction 94 47 2 to 1 Other types of collision 37 49 0.8 to 1 Noncollision accidents 37 33 1.1 to 1 All accidents 238 135 1.8 to 1 1 Unpublished data on direct costs of officially reported accidents occurring on Federal -aid primary rural highways in Illinois during 1958. 2 Accident Facts, National Safety Council, 1964. 3Interstate System Accident Research, Stanley R, Byington. Public Roads, Volume 32, No, 11, December 1963. REFERENCES a. Economic and Social Effects of Highway Improvements, An An- notated Bibliography, 1961—Warren A. Pillsbury, Virginia Council of g I • j way Investigation and Research. I b. Selected Bibliography of Cases and Materials on Highway Law, 1962— Ross D. Netherton, Counsel for Legal Research, Highway Research Board. c. Interregional Highways, .1944—House Document No. 379—U.S. ! Government Printing Office, Washington, D. C. 20402. ' d. Roadside Protection —American Automobile Association, 1951, Wash- ington, D.C. _ e. Controlled -Access Highways, Publication No. 182 Research Depart ! ment, Kansas Legislative Council, January 1953. .? j f. A Policy on Safety Rest Areas for the National System of Interstate and Defense Highways—AASHO, 1958• g. An Informational Guide on Services to Motorists 'on Interstate High- t ways—AASHO, 1961. h. House Document No. 72, 87th Congress, 1st Session, Final Report �. of the Highway Cost Allocation Study, 1961, U.S. Government Printing Office, Washington, D.C. 20402. 1 i. A Guide for the Application and Design of Frontage Roads on the National System of Interstate and Defense Highways—AASHO, 1957,, i revised 1962, j. Highway Laws References—C. L. Marinaccio and John J. Mullins, 4 Jr., Bureau of Public Roads, 1962. k. Roadside Regulations and Controls —Nicholas M: Margetis, Acquisi- tion for Right -of -Way, AASHO, 1962. t 1. Control of Highway Access, 1962—Ross D. Neth'6rton, University of Wisconsin Press.