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Choices & Guidelines

Details: Last Updated on Wednesday, 11 March 2015

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Credit: css.org/CH2M HILL Great streets and great places look beyond the lanes carrying vehicular traffic to the pedestrian realm and adjacent land uses.

The image at right depicts the symbiotic relationship between motor vehicles, buses, MetroLink, bicyclists, and pedestrians that is necessary to create great streets.

We must recognize the symbiotic relationship that is necessary for all of these modes to flourish (not simply coexist) in one common environment.

As Allan Jacobs notes: "It's no big mystery. The best streets are comfortable to walk along with leisure and safety. They are streets for both pedestrians and drivers."

In designing great streets, capacity considerations will influence how much space should be allocated to vehicular traffic, transit, bicyclists, and pedestrians.

Capacity is a basic measure of the quantity of traffic a road can carry, or more specifically, the maximum sustainable rate at which pedestrians, bicycles or vehicles can be expected to travel across a defined point or segment during a period of time, typically expressed in vehicles per hour or pedestrians per hour.

Measuring and evaluating capacity can be a complex process, particularly for arterial streets with varying conditions and a lack of uniformity between segments. Street capacity is affected by many other design considerations, such as mobility and access. Increasing the number of access points along an arterial, for example, can severely limit capacity while increasing vehicular capacity can negatively impact the mobility of pedestrians. These concepts must all be carefully balanced, for all modes, to ensure great and safe streets.

Creating great streets begins with a solid understanding of the type of place you hope to create. The appropriate role of capacity for a given roadway is determined by:

The degree to which various modes are present
Abutting land uses
The role of the arterial within the context of the network

A common mistake municipalities make is widening roadways to enhance capacity and improve the flow of vehicular traffic, without considering all its effects. Roadway widening may be appropriate along some mobility-priority corridors. However, for corridors with a significant pedestrian presence, commercial, mixed-use, or residential development, and/or widespread transit use, widening streets to increase capacity is not the preferred solution. Widening streets detracts from the pedestrian experience, jeopardizes pedestrian safety, can displace or limit development, and may discourage transit use.

Who says we need more lanes When determining the appropriate number of vehicular travel lanes for a given corridor, it is important to consider the effects of such widening on pedestrians and adjacent land uses. The Florida Department of Transportation has developed several tables which can be useful for guiding capacity choices. The tables use a set of default values to approximate the amount of traffic a facility can carry based on the number of lanes, median type, number of traffic signals, and desired level of service.

Credit: CH2M HILL

These tables were designed for general planning purposes and are most useful in assessing the overall capacity needs of a facility, as opposed to specific LOS measures such as delay or average travel speed. See the Florida LOS table for more details. Transit can be an ideal way to add capacity to an arterial street system without widening the street itself (although some transit solutions might require widening the street, too).

Credit: CH2M HILL

Bus service can reduce the number of single-occupancy passenger cars on the street, resulting in better vehicular operations overall. Dedicated bus lanes and/or bus rapid transit should be considered in arterial corridors for long-range person movement capacity.

Credit: CH2M HILL

Transit is especially effective in areas with high density land uses that can produce stable and consistent ridership. Arterial corridors with heavy through-traffic should also consider placing a higher priority on bus lanes.

In light of the expanding bus and light rail systems, St. Louis should begin prioritizing transit along the region's arterials to increase capacity and mobility for all modes. It is important to point out, however, that bus lanes and other transit capacity measures are not without their challenges. Provision of these measures, particularly at intersections, must be carefully implemented to insure that they do not negatively impact the efficiency or safety of the overall intersection. See the Intersections section of this guide for more details.

Capacity in Office Employment Areas

Primary characteristics influencing capacity for office employment thoroughfares include:

Large facilities that generate high number of trips in peak hours;
High potential for bicycle and transit mode choices; and
"Sustainable Commuting"

Depending on the target speed established for office employment thoroughfares, a variety of volumes can be serviced at several different levels. The tables below offer some general capacity thresholds, and can serve as an effective guide when considering the appropriate number of lanes to provide for a given street.

Credit: CH2M HILL

Office employment areas are typically comprised of large office buildings that house high numbers of employees, all of whom commute in some way to and from their place of employment. One of the greatest challenges in these areas is the fact that the large majority of employees arrive and depart in generally the same time frame. This "rush hour" demand creates a variety of capacity issues along the thoroughfare and beyond, especially if most employees commute via single occupancy vehicles. In these location types, roadway planners and designers should avoid automatically increasing the number of lanes along the thoroughfare and at intersections to service the ever-growing projections for single-occupancy travel.

Providing more lanes may be warranted in certain circumstances, but choosing to do so has several consequences. First, it requires more space in what is usually a very space-constrained environment. That space has to come from somewhere, and it usually means sacrificing important space in the pedestrian realm. Secondly, more lanes create wider thoroughfares. Wider thoroughfares are not always undesirable, but in general they create a less friendly environment for pedestrians. Lastly, the spike in peak hour travel in office employment areas is often significantly higher than travel throughout the rest of the day. This in many cases creates a thoroughfare that is oversized for the majority of the day.

Creating great thoroughfares will require a different kind of thinking about planning for future capacity in office employment areas. There are more efficient ways to meet the rush hour travel demand experienced in employment centers than continuing to accommodate single-occupancy vehicle (SOV) travel along the thoroughfare. As described in the general comments above, single occupancy vehicles place a much greater burden on thoroughfare capacity than high-occupancy vehicles, buses, or light rail. Implementing measures to prioritize other modes can reduce employee dependency on the SOV. Until these other modes become attractive commuting choices, they will not provide the capacity benefits they could.

Commuters that drive past transit vehicles struggling to merge back into traffic from a bus stop turnout will not see transit as a more attractive commuting choice. If, however, they watch the bus pass by in a transit-only lane or queue jumper, they may think differently about their commuting options. Similarly, seeing a bicyclist driving in the gutter, dangerously close to high-speed traffic will not promote bicycling as a commuting option. If we really want to encourage other commuting options to improve capacity, then we must go beyond our typical minimum provisions. We must provide facilities that are as safe and efficient as commuting by personal vehicle.

Bicycle Commuting Options. Avid bicyclists are typically comfortable riding on almost any road. They assert their position within the travel way to command respect from vehicular traffic. In spite of their comfort level in such conditions, they are often too exposed to traffic traveling at high speeds. Collisions can result in serious injury or even death.

For the general population who may be less comfortable bicycling on the street, commuting in this manner is not safe enough to consider as a commuting option. An unstriped sliver of pavement at the edge of the travel way is simply too intimidating for most of us to consider this as a commuting choice. Couple these typical conditions with speeds often in excess of 40 mph, and it's no wonder why so few commuters choose to bicycle to work. But what if we provided safer conditions for bicyclists? What if we reduced vehicular travel speed on streets where bicyclists travel? If we were to proactively create such conditions, there is no doubt that bicycle commuting would increase. Below are several measures that should be considered as ways to promote bicycle commuting:

Transit Commuting Options. Transit is another great way to alleviate the vehicular congestion that often plagues office employment thoroughfares. A variety of treatments and options are available to help promote and prioritize transit as an attractive commuting choice.

Transit-only Lanes. Traditionally, buses use the general vehicular travel lanes. Pull-off lanes, or pull-outs at bus stops can make it difficult for buses to reenter the stream of traffic and decrease the efficiency of transit use. Transit-only lanes can help place a higher priority on buses and other transit service. These lanes provide dedicated space on the street for buses (and sometimes bicyclists or high-occupancy vehicles) and can help make transit a more efficient, viable, and attractive choice.

Transit-only lanes can be located on the outside of the travel way (near the shoulder) or on the inside of the travel way (in the median). Transit-only lanes may be in use throughout the day, or during peak periods only.

Peak period prioritization is especially useful in areas with an extremely heavy peak period. The image at right shows an example of rush hour transit lanes that also serve bicyclists and high-occupancy vehicles (HOVs). An article from the Federal Transit Administration provides more information about Bus Lanes.

The degree to which transit lanes are appropriate is influenced by the following considerations:

Transit lanes occupy space that would otherwise be allocated to either vehicular traffic, the pedestrian realm, or storefront businesses.
Ridership levels must be high to achieve the types of capacity benefits that are possible with transit lanes. Low ridership makes transit lanes a less viable alternative.
Transit lanes require special planning and design at intersections. Care must be taken to manage the conflict between transit-only lanes and right-turning vehicles, which essentially requires a lane transition. These transitions must ensure that all users are able to safely and efficiently execute turning maneuvers. Pavement striping, clear signing, and taper lengths are important elements in effectively managing these transitions.

Transit bypass lanes, or "queue jumpers" are used to prioritize buses at intersections, allowing them to bypass congested queues forming in the vehicular travel lanes. Roadway designers should be aware of the potential conflict between transit bypass lanes and right-turning vehicles at intersections.

Appropriate location of bus stops (mid-block, nearside, or farside). The most appropriate location typically depends on site-specific characteristics. The tables at right and below describe the advantages and disadvantages of nearside, farside, and midblock bus stop locations.

Bus stop spacing is also important in prioritizing transit. The Federal Transit Administration article Stops, Spacing, Location, and Design, provides additional information on appropriate spacing and location considerations, with a focus on bus rapid transit (BRT).

Traffic Signal Priority is another way to prioritize transit along the street. Special treatments and traffic signal technologies are available to detect and prioritize transit vehicles at signalized intersections. See the Federal Transit Administration's article on Signal Priority for more information.

Prioritizing transit requires more than just transit-specific considerations. To truly prioritize transit, we must also prioritize pedestrian travel along the street. Transit inherently produces significant pedestrian traffic along the street. If safe and efficient pedestrian accommodations are not provided, transit will not be viewed as a desirable travel choice (see the Transit section of this guide for more information). As with all pedestrian accommodations, we must ensure that these elements provide safe and efficient service to persons with disabilities, as discussed in the Universal Design section of this guide.

One of the important automobile provisions necessary to serve these businesses is parking. The Parking section has a more detailed discussion of specific office area applications. Parking is an important mixed-use element that has immediate impact on employment centers, but also an impact on street capacity. While eliminating on-street parking would potentially provide an additional travel lane, on-street parking serves as an important buffer between vehicular traffic and pedestrians, improving safety and the overall quality of the pedestrian experience, while serving business interests. It also calms through-traffic by visually narrowing the roadway. This is a choice to be weighed carefully in every situation.

Sustainable Commuting. In today's world of diminishing natural resources, we ought to reward those employers and employees that choose sustainable commuting options. Carpooling, transit, bicycling, and walking are all commuting choices that minimize resource consumption and environmental impact (air pollution, noise pollution, etc.). These choices also help to improve the capacity of thoroughfares in office employment areas. Government agencies and corporations should encourage their employees to participate in these sustainable commuting options via tax incentives, vouchers, rebates, or other means to further the goal of prioritizing these other modes of commuting. If we want to change our commuting habits, we must collectively embrace these sustainable commuting options.

Maximize the outside travel lane width and provide clearly identifiable bike lane striping.
Bike lanes can also work well along corridors with designated transit lanes, because transit lanes are often relatively low-volume.
Direct trucks and other large vehicles to designated truck routes whenever possible to minimize conflicts with bicyclists.
Keep motor vehicle travel speeds as low as practicable
Ensure that drainage grates are clearly visible and bicycle friendly.
Provide secure, visible bicycle racks to discourage theft, as in the image at right.
Be vigilant about pavement maintenance and repair, especially in bike lanes; large potholes and cracks can be a serious hazard for bicyclists.

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Public utilities are a frequently overlooked element of arterial street design, despite the significant implications their placement, maintenance, and design have on roadway functionality and cost. Both underground and overhead utilities occupy a significant space within the right-of-way. See the attached PDF document for a diagram of utilities.

Utilities which are commonly overhead:

Telephone
Cable television
Overhead lighting
Electricity

Utilities which are typically underground:

Water
Natural gas
Irrigation (sprinkler systems
Sanitary sewer
Storm sewer

The poles used to support overhead utilities can present a roadside safety risk in some corridors. Specifically, 10 percent of all fatal, fixed-object crashes are a result of motor vehicle collisions with utility poles supporting overhead utility lines. If utilities must be overhead, it is imperative that the poles and cabinets are located in the areas where they are least likely to be struck by an errant vehicle. AASHTO’s Roadside Design Guide offers several design considerations for maximizing safety when roadside overhead utilities are present.

Locate power and telephone lines underground, whenever possible. Burying these lines can be costly, especially in retrofit situations but the improvement in safety, appearance, and mobility for pedestrians is worth it.
Maximize the lateral distance between the vehicular travel way and utility poles. AASHTO recommends a minimum of 18 inches between the back of the curb and the roadway. The resulting tradeoff is that the utilities are then closer to building frontages.
Reduce the number of utility poles along the street. Maximize the spacing between utility poles and whenever possible, combine multiple utilities on a single pole (e.g. combine overhead lighting with a traffic signal and perhaps even a power line).
Use a breakaway pole design. This will minimize the impact and severity of collisions.
Credit: CH2M HILL

Use traffic barriers to shield poles. While barrier curbs lose effectiveness at speeds over 30 mph, low-profile barriers (as shown at right) can be quite effective for higher speed arterials (up to 45 mph).
Preserve pedestrian walkway. Overhead utilities significantly affect the character of the streetscape. In addition to being unsightly, above ground utility poles are often located along or even in the middle of the sidewalk, encroaching on the pedestrian walkway. The clear pedestrian walkway should be a minimum of five feet wide, even when poles are present. In downtown areas sidewalks should be wider to accommodate high volumes of pedestrian traffic and pedestrians using mobility aids.
Consider maintenance of utilities in the planning process. Utility maintenance (overhead or underground) should be considered when locating utilities and other roadside elements such as trees, street furniture, traffic signs, and drainage inlets that could potentially impede or prevent access.
Coordinate early and often. Utility coordination is an essential component of the planning and design of great streets. Most streets have a number of utilities, each of which may be owned and managed by a different agency. Frequent and early coordination with these agencies can save time and money, especially when service lines are being upgraded or relocated. Coordination between roadway planners and utility agencies can improve design and lower the costs associated with roadway construction or improvements. The agency responsible should understand utility plans for the corridor and provide the appropriate utility companies with street design plans early in the process to solicit comments. Close coordination can also minimize impacts associated with construction, particularly for adjacent property owners.
Credit: CH2M HILL

Locate utilities before making improvements to an existing roadway. A thorough subsurface utility investigation should be performed before beginning work on retrofit projects to avoid discovering unexpected utility lines, and the associated costs and setbacks.

Existing plans or “as builts” can be used in combination with detection technologies such as ground penetrating radar to identify unrecorded underground utility lines along a corridor. A relatively small investment of time and money early in the planning stage can help minimize unanticipated costs during construction.
Improve the aesthetics of utilities through design, signage, lighting, and seasonal decorations. There are a variety of simple, innovative ways to transform utility hardware into attractive streetscape enhancements. For example, ordinary traffic signal cabinets can be decorated with colorful, artistic murals linking the street to the surrounding land uses, as shown in the images below. Other improvements to utility infrastructure can involve partnerships with local businesses and residents to provide and maintain amenities, such as flowers and plants, lights and decorations. Involvement by citizens and local businesses can reduce costs, enhance community buy-in, and build mutual interest in creating and maintaining great streets.

Credit: CH2M HILL

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Although most transportation research, published articles, and popular discussion focus on the movement of motor vehicles through roads and intersections, cars actually sit in parking spaces 95 percent of the time. In many urbanized areas, parking assumes 20-40 percent of the land surface area.

The design and location of parking is one of the most important elements of great streets. The quantity, location, management, cost, and design of parking depend heavily on the adjacent land use the parking is serving. For example, parking design in downtown areas is very different than parking at a suburban office complex. Still, there are several parking principles that permeate all land uses.

Ensure on-street parking: On-street parking is the most valuable type of parking for several reasons:
- It creates a physical and psychological buffer between pedestrians on the sidewalk and moving traffic.
- It presents the best access to the front door of retail, residential, and commercial destinations.
- It limits the need for off-street parking facilities. Off-site parking facilities use valuable land, require additional curb cuts through the pedestrian realm for access, and present challenges to creating good urban design. Additionally, in urban areas, off-street parking facilities can be extremely expensive.
- On a per space basis, on-street parking takes up less land area than other forms of parking because the ramps, driveways, and aisles needed in parking lots and structures are absorbed by travel lanes themselves.
Place parking behind buildings: Fronting streets with buildings (as opposed to parking) creates a more interesting, pedestrian-friendly environment. Locating parking behind buildings also allows driveways/access points to be placed on lower volume side streets, presumably with fewer pedestrians. Placing driveways (including those to parking lots) on side streets creates a more continuous pedestrian frontage, reduces the potential for pedestrian-motor vehicle conflicts, and eliminates mid-block left hand turning movements on the higher volume street - a leading cause of mid-block congestion.
Encourage shared parking: Peak parking demand for adjacent land uses often occurs at different times of the day. For example, a bank and a neighboring movie theater could feasibly share spaces as their parking demand peaks at different times. Although such arrangements are more common in mixed-use district, shared parking can be implemented in all place types. Shared parking decreases the need for off-street parking spaces and lots, which imparts many of the benefits mentioned above. See the Urban Land Institute’s Shared Parking (Smith. Shared Parking, Second Edition. ULI and the International Council of Shopping Centers. 2005) for more information about shared parking.
Source: ADAAG
Provide handicapped parking: Federal law requires that handicapped parking be provided in all designated parking areas. The Americans with Disabilities Act (ADA) sets guidelines for handicapped parking requirements for all new construction. The minimum number of required handicapped spaces is based on the total number of spaces in the parking facility, as outlined in the figure at right.

The location of these spaces is also regulated, as explained below in the ADA Accessibility Guidelines:

“Accessible parking spaces serving a particular building shall be located on the shortest route of travel from adjacent parking to an accessible entrance” (ADAAG 4.6.2).

Although there are established national standards, individual municipalities often set their own standards for handicapped parking. A 1990 study of retail shopping centers found that the number of handicap spaces in commercial areas varied between 0.7% and 2.0% of the total parking supply (Weant and Levineson. Parking Spaces. McGraw Hill. 1999).
Include bicycle parking: Although automobiles typically come to mind when parking is mentioned, great streets have provisions for all modes, including adequate and secure bicycle parking. There are no national standards for bicycle parking, and local requirements vary widely. One of the most convenient methods for establishing appropriate bike parking design is to view the ordinances of municipalities with high bike mode shares. The city of Madison, Wisconsin, for example, provides excellent guidelines on the appropriate quantity, location, and design of bike parking. The city of Portland, Oregon also has an excellent web page with guidelines for installing bicycle parking.
Minimize supply: Parking is often oversupplied, which creates a number of design challenges. A 2003 study of 42 parking lots during the holiday season found that the average occupancy was less than half (Gould. “Parking: When Less is More.” Transportation Planning, Vol.28, No.1. Transportation Planning Division, APA. Winter 2003).
Source: City of Seattle
Retail shopping centers with massive parking facilities that are rarely (if ever) full are a common sight in most communities. Parking is oversupplied because the minimum parking requirements for residential and commercial development is often set at the annual maximum expected demand, leaving excess parking for much of the year.
Ensure delivery parking: Delivery parking must be provided in most, if not all, place types, but is particularly important in areas with a high concentration of retail shops and restaurants. Alleys are ideal locations for temporary truck parking, allowing back door delivery access away from customer parking and entrances. When alley use is not feasible, special loading zones can be designated. The image at right is an example of signage used in a loading/unloading zone.

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Source: FHWA An intersection is defined as the area where two or more roadways join or cross, but also includes elements of the functional area, such as intersection approaches, medians, sidewalks, bike lanes, and other roadside features.

The image at right highlights the physical and functional areas of an intersection.

Intersections on great streets must serve all modes of travel.

Automobiles, transit vehicles, pedestrians, and bicyclists should all be given adequate time, space, and directional cues to safely proceed through intersections and continue traveling along the arterial. Balancing the needs of all users at multimodal intersections, while maximizing substantive safety is a complex and important challenge.

Source: FHWA

Intersections are points of conflict where modes of travel converge, as illustrated in the image at right.
Intersections should be carefully designed to include and prioritize the most appropriate place-specific design elements.
Intersecting roadways should cross at an angle of at least 75 degrees, ideally 90 degrees. When the angle of intersection is less than 60 degrees special design treatments may be needed to ensure a reasonable level of safety.
At intersections, medians can be used to provide separation between opposing traffic, channelization for turn lanes, and refuge for pedestrians.
Medians with landscaping and tree plantings can also be used to improve intersection (or roadway) aesthetics, although care should be taken not to affect driver or pedestrian visibility and sight distance.

Credit: FHWA

Movement through intersections is controlled using yield signs, stop signs, roundabouts, and traffic signals. The appropriate type of control for a given intersection depends on the place type and the amount of pedestrian and vehicular traffic.

The MUTCD provides guidance for selecting the appropriate type of control for various intersection conditions (see the following links for general information and specifics about signal warrants).

Different traffic control devices impose varying degrees of delay on pedestrians and vehicles passing through the intersection. The overall efficiency and capacity of a roadway is limited by the delay experienced at its intersections.

Some agencies and municipalities continue widening intersections by adding exclusive, dual, or even triple turn lanes in an effort to minimize delay along the arterial. While these improvements do increase an intersection's vehicular capacity, they also render the intersection more difficult for other modes of travel (especially pedestrians) to navigate. Because turn lane additions are typically retrofit projects they can significantly impact surrounding residences, businesses, and land parcels.

Designing intersections for great streets requires balancing competing needs, interests, and values, and responding to the unique circumstances of each street. Planners, designers, policy makers, and local stakeholders should collaborate to develop a community vision which can be used to guide the design and construction of intersections and roadway improvements.

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Source: FHWA Access refers to the demand for vehicular entry and exit to and from driveways and crossroads that intersect with an arterial. These driveways and crossroads are commonly referred to as access points. Access points present a number of planning and design challenges and potential hazards along the roadway. Each access point represents a potential conflict between turning and through-moving vehicles, pedestrians, and bicycles on the arterial, as illustrated in the diagrams at right. Greater access point density increases the number of potential conflicts along an arterial.

Source: FHWA

Access management refers to the regulation of access point location and spacing and is a crucial part of creating a great street that is safe for all modes. Access management is intended to balance mobility for through-traffic and access for vehicles attempting to enter or leave the roadway, while ensuring maximum safety for all users. Typically, a roadway's functional classification guides the location and spacing of access points.

Access management plans must be site-specific and place-based. The figure at right depicts the traditional relationship between access and functional classification.

Source: FHWA

At the top of the functional class hierarchy (principal arterial freeways), mobility is provided at the expense of access; at the bottom (the local road system), extensive access is provided, which limits mobility. Planning and designing great streets requires finding the most appropriate balance between access and mobility, according to place type. While local guidelines can sometimes be useful, standard solutions based solely on functional classification rarely produce desirable outcomes.

Tradeoffs are inherent in every roadway access point decision. Balancing competing interests is critical to successful implementation, and is perhaps one of the biggest challenges in designing great streets. Allowing unlimited access points would undermine the safety and efficiency of the arterial street. Conversely, prohibiting all access would render adjacent properties essentially worthless.

Source: FHWA

Access must be considered on a case-by-case basis. The owning transportation agency (the state, county, or local municipality), controls access rights along roadways within a jurisdiction. Most agencies have policies in place to regulate new and existing access point development. Nonetheless, access plays such a critical role in determining the environment along a roadway that planners, designers, and stakeholders are encouraged to carefully examine projects on a case-by-case basis.

Site-specific conditions and community objectives should always be taken into account when deciding how to manage and control roadway access. Specific spacing requirements will vary based on site-specific conditions. The ITE Traffic Handbook Table 10-5 provides guidance for minimum spacing requirements.

MoDOT's Access Management Guide identifies four major goals of access management:

Improve roadway safety;
Improve traffic operations;
Protect taxpayer investment in the roadway; and
Create better conditions for non-motorized modes of travel.

MoDOT emphasizes that the guidelines are intended to allow for flexibility when necessary, and their overarching goal is to provide a safe and efficient transportation system while balancing the need for access to abutting land uses. Broad standards should not be applied without careful consideration of a project's unique characteristics.

Traffic impact studies should consider the large-scale transportation network (current and planned) before access permits are granted. Developers are typically required to conduct a traffic impact study before gaining approval for new developments. Unfortunately, each individual development usually conducts its own study, failing to capture the cumulative impacts of all proposed developments in the area. In such cases, a project may be approved because its impact on the roadway seems reasonable, but the combined impact of several projects can create traffic problems along the arterial.

Access in Office/Employment Areas:

Employment corridors are usually comprised of numerous large office employment centers that generate a high travel demand during the morning and evening rush hours. Promoting multi-modal access throughout these corridors can help reduce peak period congestion. Providing a variety of travel options also creates a more attractive environment for prospective employees and businesses. Office/employment areas have:

Credit: CH2M HILL

High travel demand during rush hour;
Significant transit presence; and
Significant pedestrian presence.

As the regional transit system in St. Louis continues to expand, provisions for bus and light rail commuters should be a centerpiece of street design in office employment areas. Providing adequate and efficient access for buses along the street will encourage transit use and limit the impact of bus service on vehicular roadway capacity.

Plan for pedestrians and bicycles. These thoroughfares should prioritize pedestrians along the street, and especially at the intersections. Intersections will provide the vast majority of vehicular access along the street, so it is vitally important to provide safe, efficient crossings and refuges for pedestrians at these locations. Special signage to remind drivers to watch for pedestrians, as shown in the image at right, can be useful in managing this conflict when curb cuts and driveways are required.

Bicycles are another important mode along these streets, and they will also be at conflict with access points along the corridor. Whether bicyclists travel along a marked bicycle lane, a wide outside lane, or along a shoulder, they will inevitably have to cross driveways and intersections. Where regular bicycle use is expected/desired, driveways should be limited to the extent practicable. Bicycle-specific measures should be provided at intersections to prioritize bicycling at these locations.

The crossroad access points/intersections will generally be either signalized or unsignalized. Signalized access points can provide a safer pedestrian environment by including pedestrian crossing signals and, if appropriate, restricted turning movements during pedestrian crossings. For signalized intersections, regular spacing is beneficial for the efficiency of the greater thoroughfare. Minimum signal spacing for these place types should be one-quarter mile.

Unsignalized intersections are more frequent and create more potential conflicts between cars, pedestrians and bicycles. They are usually controlled by stop signs on the minor road without stopping traffic on the thoroughfare itself. They may represent a minor road crossing, a parking lot entrance, or an atypical larger parcel entrance. Pedestrian visibility is always important, but even more so at unsignalized intersections.

Reduce points of conflict. Access points create conflicts for through-moving vehicles, pedestrians and bicycles. Drivers are typically focused on vehicular traffic when attempting to enter or exit an arterial, and may fail to see a pedestrian crossing the driveway or a bicycle approaching. Drivers fixated on traffic approaching from the left may edge out onto the arterial without looking again to the right to check for pedestrians. In areas with a significant pedestrian presence, the number of driveways should be minimized to the extent practicable. At higher volume access points, signage reminding drivers to watch for pedestrians can be used to minimize conflicts.

Provide access to/from parking garages on secondary streets. Office/employment areas often have significant parking requirements. These lots and garages may serve as park-n-ride transit lots or lots serving the commuting employees who work in the respective place. The parking capacity often provided by these facilities is significant, and places a concentrated demand on the surrounding road network during peak hours.

Source: FHWA

The best way to manage the provision of access for these large parking facilities is to locate them off of the arterial street, either on cross roads or "backage" roads. Such provision of access will minimize conflicts on the arterial resulting from direct driveway access. When this is not possible and direct driveway access onto the arterial is required, spacing of the driveway(s) with respect to other crossroads and driveways is very important. These driveways at a minimum should be located outside of the functional areas of nearby intersections. Preferably they should be spaced as far from the next closest up- and downstream access points as practicable.

Prioritize transit access. In these place types, transit must be prioritized. Mobility for transit, in the form of bus-only lanes and queue jumpers (also called queue bypass lanes) can help in this effort but require careful consideration of access along the street. In the figure at right, the no-build condition represents a typical transit provision where buses must share the outside travel lane. The queue jumper condition expands the no-build condition to include a bypass lane for buses at intersections. See Chapter 10 of ITE's Context Sensitive Solutions in Designing Major Urban Thoroughfares for Walkable Communities for more information about queue jumpers and prioritized transit.

The transit lane (could also be a shared transit/HOV/bike lane) condition provides a continuous bus-only lane throughout the entire corridor. These concepts can be very effective in prioritizing mobility for other modes, but they do have impacts on abutting access requirements. When such measures are provided on the outside of the travel way, they will conflict with every driveway along the corridor.

Managing the location and spacing of such driveways, then, is imperative in order to encourage transit along the street. Failure to do so will inhibit the intended prioritization of transit. Spacing guidance should be developed on a case-specific basis, and it should be coordinated with local businesses and residents whose parcels abut the street. When transit lanes are provided down the center of the street, as in the image at right, conflicts with adjacent driveways are lessened. The center location, however, creates another set of conflicts to manage the movement of pedestrians to and from median transit stops. Pedestrian crossings, perhaps even mid-block pedestrian signals, should be provided in close proximity to median transit stops.

Such access must be provided efficiently and safely, without degrading operations for other modes along the corridor. Three general options are available for bus stop location: mid-block, near side, and far side. The tables at right describe the advantages and disadvantages to consider for each of these conditions. Each specific site condition will have characteristics that influence the best choice for bus stop location, and it is imperative that they be examined as such. There is no "one size fits all" solution that should be applied blindly across an entire corridor.

Regardless of location, clear and visible signing should be present to aid pedestrians in locating nearby bus stops. Chapters 9 and 10 of the ITE guide Context Sensitive Solutions in Designing Major Urban Thoroughfares for Walkable Communities provide additional information on these subjects.

Use raised medians, when appropriate. Ideally, thoroughfares in office/employment areas will have vehicle speeds that make for a safe pedestrian environments and narrow crossings at intersections. However, it is possible that a thoroughfare through office/employment areas could be improved with the use of raised medians, when there is adequate right-of-way and need for the following improvements.

Raised medians reduce the number of access-related conflicts. Access to driveways is confined to right-in, right-out movements, reducing the number of potential conflicts from nine (9) to three (3) at a standard 3-legged intersection (see Oregon PDF for additional detail on right-in, right-out channelization design). Left turn movements are restricted to access points across from a gap in the median. Because turning movements are restricted, the network must allow appropriate access to both sides of the street through allowed u-turns, roundabouts, and/or an improved (in some cases, one-way) grid on the neighboring streets.
Raised medians can help reduce vehicle speeds by creating more visual friction in the thoroughfare. The visual impact of a median can slow vehicle speeds and appropriately calm traffic to improve safety along the thoroughfare.
Raised medians provide opportunity for pedestrian refuges, when crossing distances are long. Raised medians with this purpose should include a preferred minimum refuge width of 6 feet if pedestrians are intended to remain in the refuge during a signal cycle. These medians should extend beyond the crosswalk towards the intersection for pedestrian safety. Design of the refuge should include application of turn templates for trucks and the design vehicle for u-turns. Reflectors and raised delineators as well as the use of colored concrete can increase the visibility of the median refuge as well as the pedestrians using it. The figure below/at right shows a pedestrian refuge island that addresses some of these safety concerns. The image on the left is a collage of pedestrian refuge designs from cities throughout the U.S. and Europe. Although wider refuges are desirable, narrow width (e.g., 4-foot-wide) pedestrian refuges do meet minimum width requirements identified in many of the U.S. documents on urban thoroughfare design. AASHTO's "Policy on Geometric Design of Highways and Streets" (2001) says that 4 feet is the minimum width. ITE's Design and Safety of Pedestrian Facilities (March 1998) states that the minimum width for pedestrian refuge island is 4 feet.
Raised medians provide the opportunity for attractive landscaping. See the safety section of this guide for more information about issues related to trees or other fixed objects in the median. Landscaping, along with other objects in the median should allow for the recommended clear zone. AASHTO recognizes that "space for clear zones is generally restricted" and suggests that a "minimum offset distance of 18 inches should be provided beyond the face of the curb." AASHTO also suggests that "since most curbs do not have a significant capability to redirect vehicles, a minimum clear zone distance commensurate with prevailing traffic volumes and vehicle speeds should be provided where practical." Design speed is an important factor relating to crash risk and severity. Other considerations include review of accident history involving lateral obstructions on the project of concern or for similar thoroughfares.

Washington State is currently conducting an in-service review to evaluate actual safety performance related to obstructions in medians. The in-service review establishes an agreement to monitor safety performance of the constructed features and to implement appropriate mitigation measures if necessary. Some design mitigation concepts include use of shoulders and auxiliary lanes to increase clear zone separations. For example, curb lanes used for transit and turning vehicles only, would have lower volumes and lower speeds than through lanes. Therefore, these auxiliary lanes provide a separation between the through lanes and adjacent vertical objects.

Raised curbs, raised planters and barriers are also being evaluated as means to redirect vehicles or reduce severity of crashes. Lighting in the median may be considered to improve visibility of medians for drivers under night conditions. The figure here shows a low profile barrier that has passed crash testing and is being used by CH2M HILL on a median for a downtown thoroughfare project.

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