Click for next page ( 46


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 45
45 FIGURE 23 Examples of left-turn lanes. Source : Koepke and Levinson (6, p. 71). whether a channelized right-turn lane should be installed Survey Results at an intersection as well as a number of typical design dia- grams for situations in which channelized right-turn lanes This section summarizes the survey results obtained from are desirable (72). state DOTs and local agencies regarding the structure and contents of their access management programs. The pri- AASHTO provides guidance related to the design of each mary purpose of asking the survey questions reflected in component of the right-turn auxiliary lane (8). The three this section was to identify what access management pro- components are the (1) taper, (2) deceleration length, and (3) gram elements are in place at transportation agencies in the storage length. United States.

OCR for page 45
46 Overview of Access Management Programs The most common access management program elements being developed by state DOTs include guidelines (44%), The contents of access management programs vary widely general department policies (36%), driveway permit manu- by state. Table 14 illustrates a variety of general program als (31%), and standards (31%). Ten state DOTs (22%) indi- elements--such as policies, guidelines, and standards-- cated they are developing new access codes or are enhancing used by state DOTs to enhance access management their existing code. implementation. Tables 16 and 17 show a range of specific techniques typi- Of the 50 state DOTs, 39 (78%) indicated that they had cally applied in access management and list which of the 50 general department policies related to their access manage- state DOTs currently apply these techniques. ment program. Other common program elements currently in use include guidelines (37 state DOTs, or 74%), driveway More than 80% of all state DOTs indicated that they apply permit manuals (35 state DOTs, or 70%), roadway design the following access management techniques: manuals (33 state DOTs, or 66%), and standards (29 state DOTs, or 58%). Installation of medians Spacing for median openings In general, state DOTs with access codes, and the asso- Unsignalized access and intersection spacing ciated statutory authority or administrative rules, are gen- Traffic signal spacing erally better suited to manage access along state highways, Turn prohibitions because the necessary legislative support exists and the Corner clearance regulatory documentation is in place. The police powers of Spacing on crossroads in interchange areas the state can be used as the enabling legislation. Intersection sight distance and setbacks Driveway geometric design standards The Colorado DOT was the first state to develop a com- Right-turn and left-turn lane provisions prehensive access code, in 1981. Access codes were sub- Requirements for traffic impact studies sequently developed by other state DOTs, including New Jersey DOT, Florida DOT, and Oregon DOT. Of the 50 state Access rights are purchased by 66% of all state DOTs. DOTs, the following 19 (38%) indicated that they currently Internal connections of parking lots between adjacent par- have an access code: cels and subdivision restrictions for large parcels are applied, respectively, by 48% and 30% of all state DOTs. Some 16% Arizona DOT of all state DOTs have requirements for traffic impact fees. Colorado DOT Florida DOT Among the 43 respondents for local agencies, the most Idaho DOT common access management techniques cited included Illinois DOT general departmental policies (56%), guidelines (49%), use Iowa DOT of a driveway permit manual (44%), and standards (37%). Kansas DOT The following 10 local agencies indicated that they currently Montana DOT have access codes: Nebraska DOT New Jersey DOT Forsyth County (Georgia) New Mexico DOT McHenry County (Illinois) Oregon DOT Hancock County (Indiana) Pennsylvania DOT Harford County (Maryland) South Dakota DOT Licking County (Ohio) Utah DOT Washington County (Oregon) Virginia DOT City of Durham (North Carolina) Washington DOT City of Tigard (Oregon) Wisconsin DOT City of Federal Way (Washington) Wyoming DOT RochesterOlmstead Council of Governments (Minnesota) Based on the results of the 45 state DOTs that completed the entire survey, Table 15 illustrates general program Access Classification Systems elements that currently are being developed or refined by state DOTs to enhance the implementation of access An ACS is a fundamental element of any access management management. program. The synthesis survey revealed that 27 of the 50 state DOTs (54%) have a formal ACS, and 14 others (28%) indicated

OCR for page 45
47 TABLE 14 ACCESS MANAGEMENT PROGRAM ELEMENTS CURRENTLY IN USE BY STATE DOTS (50 RESPONSES) Statutory Authority General Driveway Access Roadway State or Administrative Departmental Code Standards Guidelines Permit Rules Policies Design Manual Manual AL X X X AK X X X X AR X X X X X AZ X X X CA X X X X X CO X X X X CT X X DE X X X X FL X X X X X X X GA X X X X X X HI X X IA X X X X X ID X X X X IL X X IN X X X KS X X X X X X X KY X X X X LA X X X MA X X X X MD X X X X X ME X X X MI X X X X MN X X X MO X X X X X MS X X X X X MT X X X X X X X NC X X X X ND X X X X X NE X X X X X X X NH X X X NJ X X X X X X NM X X X NV X X X NY X OH X X X X OK X X X X X OR X X X X X X X PA X X X X X RI X X X X X SC X X X X SD X X X X TN X X X X X TX X X X UT X X X X X X X VA X X X X X X VT X X X X WA X X X X X X WI X X X X X X WV X X X X X WY X X X X

OCR for page 45
48 TABLE 15 ACCESS MANAGEMENT PROGRAM ELEMENTS BEING DEVELOPED OR REFINED BY STATE DOTS (45 responses) General Departmental Driveway Permit Roadway State Policies Access Code Standards Guidelines Manual Design Manual No Changes AK X X AR X X AZ X X X X X CA X X X CO CT X DE X FL GA X X X HI X X X IA X X X X ID X X IN X X X KS X X X X X X KY X X LA X X X X MD ME X MN X MO X MS X X X X X MT X X X X X NC X X X X ND X X NE X NH NJ X X NM X NV NY X X OH X X OK X X OR RI X SC X X X SD TN TX X UT X X VA X X X VT X WA X X X WI X X X X X WV X WY

OCR for page 45
49 TABLE 16 TYPICAL ACCESS MANAGEMENT TECHNIQUES APPLIED BY STATE DOTS (50 RESPONSES) Corner clearance (distance from Spacing for Spacing for Spacing for Prohibition of a public street cross-streets in Installation of Spacing for median unsignalized public unsignalized private Spacing for certain turning intersection to the the vicinity of State medians openings/breaks street intersections driveways traffic signals movements first driveway) interchanges AL X X X X X X X AK X X X X X X X X AR X X X X X X X X AZ X X X X X X X X CA X X X X X X X X CO X X X X X X X X CT X X X X X X X X DE X X X X X X X FL X X X X X X X X GA X X X X X X X X HI X X X X X X X X IA X X X X X X X X ID X X X X X X X IL X IN X X X X X X KS X X X X X X X X KY X X X X X X X X LA X X X X MA X X X X X X X X MD X X X X X X X X ME X X X X X MI X X X MN X X X X X X X MO X X X X X X X X MS X X X X X X X X MT X X X X X X X X NC X X X X ND NE X X X X X X X X NH X X X X X X X NJ X X X X X X X NM X X X X X X X X NV X X X X X X X X NY X X X X OH X X X X X X X OK X X X X X X X X OR X X X X X X X PA X X X X X X X X RI X X X X X X SC X X X X X X X SD X X X X X X X TN X X X X X X TX X X X X X X UT X X X X X X X X VA X X X X X X X X VT X X X X X X X WA X X X X X X X X WI X X X X X X X X WV X X X X X X X X WY X X X X X

OCR for page 45
50 TABLE 17 TYPICAL ACCESS MANAGEMENT TECHNIQUES APPLIED BY STATE DOTS (50 RESPONSES) Internal connection of Intersection Geometric Provisions for parking lots Subdivision Requirements Requirements sight distance design standards right-turn and Purchase of between restrictions for for Traffic for Traffic State and setbacks for driveways left-turn lanes access rights adjacent parcels large parcels Impact Studies Impact Fees AL X X X X X AK X X X X X X X X AR X X X X X AZ X X X X X X CA X X X X X X X X CO X X X X X X X CT X X X X X X X DE X X X X X X FL X X X X X X GA X X X X X X X X HI X X X X X IA X X X X X ID X X X X X IL X X X X X IN X X X X X KS X X X X X X KY X X X X X LA X X MA X X X X X MD X X X X X X X ME X X X MI X X X X MN X X X X MO X X X X X X MS X X MT X X X X X X X NC X X X X ND NE X X X X X X NH X X X X X NJ X X X X X X NM X X X X X NV X X X X X X X NY X X X X X OH X X X X X OK X X X X X X X OR X X X X X X PA X X X X X X RI X X X X X X SC X X X X SD X X X X TN X X X TX X X UT X X X X X X X VA X X X X X X VT X X X X X WA X X X X X X WI X X X X X X X X WV X X X X X X WY X X X X

OCR for page 45
51 that they rely on the functional classification system for access stops, even under moderate traffic volume conditions. Fig- management purposes. The remaining nine states indicated that ure 25 illustrates the most commonly cited variables used by they did not have an ACS. Figure 24 illustrates the most com- state DOTs for establishing traffic signal spacing criteria. monly cited elements considered among the state DOT ACSs. The primary variables used by state DOTs to establish The more common considerations cited by the state DOTs traffic signal spacing criteria are speed (56%), cycle length in their ACS are functional classification (58%), urbanrural (49%), allowable movements (38%), and bandwidth (27%). environment (56%), and posted speed (42%). Other consid- "Other variables" for traffic signal spacing noted by respond- erations include traffic volume (38%), number of travel lanes ing state DOTs included the following: (31%), and type of median cross-section (31%). Roadway classification Of the 43 local agencies that responded to the survey, only Roadway access category 8 (19%) indicated that they had an ACS, and 16 (37%) indi- Safety considerations leading to alternative solutions cated that they rely on the functional classification for access (other than a traffic signal) management purposes. The remaining 15 local agencies (35%) Urban versus rural distinctions indicated that they do not have an ACS, and 4 agencies (9%) Traffic volumes did not respond. The most commonly cited ACS elements cited Accident rates by the local agency respondents were traffic volume, functional Adequate stacking distance classification, urban-rural distinction, and number of lanes. Adjacent land use Sight distance Access Features Fixed spacing distances are applied (ranging from 0.25 mi to 1 mi) Signal Spacing The most commonly cited variables used by the Establishing criteria for traffic signal spacing--in terms of responding local agencies included allowable movements frequency and uniformity--is one of the most important and (33%), speed (21%), cycle length (19%), and bandwidth basic highway access management techniques, because traf- (19%). fic signals govern the performance of urban and suburban highways and account for most of the delay that motorists As traffic volumes increase over time, longer cycle experience. Closely or irregularly spaced signals can reduce lengths may be introduced to accommodate additional arterial travel speeds and result in an excessive number of signal phases, improve intersection capacity, and reduce FIGURE 24 Most commonly cited elements considered in state DOT access classification systems (45 responses).

OCR for page 45
52 FIGURE 25 Most commonly cited variables for traffic signal spacing (45 responses). overall delays. Longer cycle lengths, however, also can increases the potential for crashes. Increasing the spacing result in longer delays and longer queues, and make effec- between the access points improves traffic flow and safety tive signal coordination more difficult. In practice, cycle along the highway by reducing the number of conflicts per lengths of 120 s (2 min) or more are generally considered mile, providing a greater distance for motorists to anticipate to be long, with 180 s (3 min) a practical maximum for and recover from turning maneuvers, and providing oppor- acceptance by motorists. Minimum cycle lengths gener- tunities for the construction of turn lanes. Figure 28 indi- ally range between approximately 45 s and 60 s. Figures cates the most commonly cited criteria by state DOTs for 26 and 27 illustrate the ranges of maximum and minimum driveway location and design. cycle lengths, respectively, typically implemented by state DOTs. The most common driveway location and design crite- ria cited by the state DOTs are related to development type The maximum cycle lengths typically implemented by (93%), development size or intensity of use (91%), location state DOTs are 120 s or less (36%), 130 to 170 s (30%), and (84%), functional classification (80%), and posted speed 180 s or more (34%). Of the 17 local agencies that responded (80%). "Other criteria" cited included the following: to this question in the survey, 6 (35%) indicated maximum cycle lengths of 90 to 120 s, and 8 (47%) indicated maximum The location of adjacent driveways and intersections cycle lengths exceeding 120 s. Corner clearance Opportunities for alternative access (i.e., from side The minimum cycle lengths typically implemented are streets) 60 s or less (80%), 70 to 80 s (7%), and 90 s (13%). Of Opportunities for shared access with adjacent the 17 local agencies that responded to this question in the properties survey, 12 (71%) indicated minimum cycle lengths of 30 to Accident experience 60 s, and 2 (12%) indicated minimum cycle lengths of 90 Intersection level of service s or more. Sight distance Precedence set by previously allowed driveway loca- Unsignalized Spacing tions along the same (or a similar) corridor Unsignalized driveways and street intersections introduce For local agencies, the most common driveway location conflicts and friction into the flow of traffic along a highway. and design criteria cited are related to roadway classification Vehicles entering and leaving the highway at these locations (65%), development size or intensity of use (63%), develop- often slow the movement of through traffic, and the differ- ment type (60%), posted speed along the roadway (60%), ence in speeds between through traffic and turning traffic and development location (47%).

OCR for page 45
53 FIGURE 26 Maximum cycle lengths typically implemented by state DOTs (30 responses). FIGURE 27 Minimum cycle lengths typically implemented by state DOTs (30 responses). The synthesis survey revealed that 31 of the 50 state DOTs the final decision may be elevated to a higher authority within (62%), and 21 of the 43 local agencies (49%), stated that they the agency, such as a statewide access engineer or an access have provisions for instances in which the spacing criteria and review committee. Of the remaining agencies, 16 state DOTs geometric design standards cannot be met. These provisions (32%) and 13 local agencies (30%) indicated that their agency usually involve a variance, waiver, or design exception pro- did not have any such provisions. Three state DOTs (6%) and cess, and are considered on a case-by-case basis. At DOTs, nine local agencies (21%) did not respond to this question.

OCR for page 45
54 FIGURE 28 Most commonly cited state DOT criteria for driveway location and design (45 responses). Access Permit Process Staff decisions that are not supported by administra- tive rules State and local agencies typically use access permitting to Lack of "reasonable access" apply access management standards to development. A well- Undue financial hardship would be imposed on the conceived and applied access permitting program is essen- property owner tial for effective access management. All of the state DOTs Unreasonable or costly roadway improvements are surveyed have a driveway permit process. The majority of required states (37 of the 45 state DOTs responding to the entire sur- Inconsistencies in the application of access criteria vey, or 82%) stated that the permit process also applies to across districts or regions within the same state changes in existing land uses, as well as to new develop- ments. Of the 43 local agencies responding to the survey, Within state DOTs, appeals of access-related decisions 32 (74%) indicated that they had a driveway permit process, typically are made to successively higher levels of manage- and 17 of those 32 (53%) indicated that the permit process ment, from the subdistrict or district level, to the central also applies to changes in existing land uses. office or headquarters office level, and to a chief engineer, director, or commissioner level. Many state DOTs use a Figure 29 illustrates percentages of responding DOTs that committee to render access decisions in an appeal situa- utilize each of several common access enforcement actions. tion, for example: Of the 45 state DOTs responding to the entire survey, 31 Appeals Committee (Ohio DOT) (69%) indicated that their agency had a process for an appeal Appeals Board (New Hampshire DOT) by the permit applicant. Similarly, 23 of the 43 responding Access Management Review Committee (Maine DOT) local agencies (53%) indicated that their agency had an Access Control Committee (New Mexico DOT) appeals process. Most of the state DOTs and local agencies Driveway Permit Appeals Committee (North Carolina indicated that any access-related decision could be appealed DOT) (in writing) by the applicant, including access denials and State Transportation Board (Vermont DOT) decisions related to the terms and conditions of the access Transportation Commission (Colorado DOT) permit (e.g., driveway location, turning movement restric- tions, and requirements for auxiliary lanes). Applicants Among local agencies, access-related decisions typically often appeal access decisions on the basis of the following: can be appealed to the local planning board or commission, county board of supervisors or commissioners, city coun- Disagreement over the interpretation of engineer- cil, or another similar governing body. Ultimately, access- ing criteria, particularly in unique, site-specific related decisions can be challenged in the applicable state or circumstances local court system.

OCR for page 45
55 FIGURE 29 Common access enforcement actions undertaken by state DOTs (45 responses). Traffic Impact Studies Of the 45 state DOTs responding to the entire survey, 43 (96%) indicated that the TIS is used to identify transporta- Survey participants were asked to identify the circumstances tion system improvements to mitigate traffic impacts. Only under which a TIS would be prepared as part of the access five state DOTs--Alaska, California, Maine, New Hamp- permit application process. The responses varied widely. shire, and Washington--indicated that a Traffic Impact Of the 45 state DOTs that responded to the entire survey, Fee (TIF) can be collected by the state. Respondents from 37 (84%) indicated that traffic volume was a key determin- Alaska, California, and New Hampshire indicated that the ing factor regarding whether or not a TIS was required and TIF is assessed based on projected traffic impacts, whereas 14 (31%) indicated that their agency applies a threshold of Washington DOT also uses land use type and size to deter- 100 peak-hour trips in some manner in the determination of mine the TIF. Maine DOT assesses a TIF in lieu of improve- whether or not to conduct a TIS. Other circumstances cited ments in areas in which the department may have an ongoing by the responding state DOTs as reasons for conducting a highway improvement project. It was noted by several states TIS included the following: that TIFs are often assessed by MPOs, counties, or other local agencies, rather than the state DOT. Safety concerns exist or are anticipated Development is proximate to a highly congested area Based on the survey responses, 40 of the 45 state DOTs Request for a new traffic signal, or where signal war- responding to the entire survey (89%) indicated that the prop- rants will be met erty owner, permit applicant, or developer was responsible Proposed changes to a median or median opening for paying for any necessary on-site improvements, whereas Need for a turn lane 3 (7%) responding state DOTs indicated that the on-site Proposal for certain types of land uses, particu- costs were negotiated or shared among the state, local gov- larly high-volume uses, or those with sharp peaking ernment, and the property owner, permit applicant, or devel- characteristics oper. Of the 31 local agencies responding to this question, 30 Unusual geometric conditions (97%) indicated that the property owner, permit applicant, or Unique site considerations developer was responsible for paying for any necessary on- A variation from the access standard is expected site improvements, whereas 1 (3%) indicated that the on-site Local agency has requirements for a TIS costs were negotiated or shared between the county and the At the district or state traffic engineer's discretion property owner, permit applicant, or developer.

OCR for page 45
56 For off-site improvements, 34 of the 45 state DOTs responding to the entire survey (76%) indicated that the property owner, permit applicant, or developer was respon- sible for paying, whereas 8 (18%) indicated that the off-site costs were negotiated or shared among the state, local gov- ernment, and the property owner, permit applicant, or devel- oper. Of the 31 local agencies responding to this question, 24 (77%) indicated that the property owner, permit applicant, or developer was responsible for paying for any necessary on- site improvements, whereas 5 (16%) indicated that the on-site costs were negotiated or shared between the local agencies and the property owner, permit applicant, or developer.