Alternatives Examined Roadway Alternatives
Recommended Alternative 1
Alternative 2
Alternative 3
Alternative 4
Recommended Alternative 1 • Two lanes • Center median/turn lane • On-street parking • Bulb-outs • Pedestrian refuges • Landscaping/street trees • Bike traffic directed to residential streets
Roundabout Alternative To address the offset Constitution intersection and help reduce the number of crashes at the intersection, the planning team examined the possibility of installing a roundabout. Single-lane roundabouts, which are the most common, help to significantly reduce vehicle speeds and crash rates, since drivers must pay more attention while approaching the roundabout. In a roundabout, the conventional fourway traffic signal is replaced by a circular intersection. Instead of a traffic signal, traffic on all sides must yield to vehicles in the roundabout. From a roundabout, drivers can turn onto any of the connecting streets (Figure 5).
Alternative 2 • Two lanes • On-street parking • Bulb-outs • Bike lanes • Some landscaping/street trees • No median/turn lane • No pedestrian refuges Alternative 3 • Two lanes • Center median/turn lane • Bike lanes • Pedestrian refuges • Landscaping/street trees • No on-street parking • No bulb-outs Alternative 4 • Four lanes • Lanes shrunk from 12 feet to 11 feet • Center median • Small pedestrian refuges • Minimal landscaping • No turn lanes • No bulb-outs • No on-street parking • No bike lanes
Intersection Alternatives Constitution Intersection (Straightened) • Road shifts slightly to reduce angle from 8° to 4° • Requires small right-of-way acquisition on NW corner • Road stripes help guide cars through intersection • Median helps steer traffic Constitution Intersection (Roundabout) • Reduces vehicle speeds & crashes • Improves traffic flow • Pedestrian refuges for crossing • Requires significant right-of-way acquisition • Implications for school crossing unclear
Figure 1: Cross-Sections of Recommended Alternative 1. The top figure indicates the normal alignment, and the bottom figure shows the alignment at pedestrian crossings. Recommended Alternative 1 is a refined version of the recommended alternative presented on July 2, and it received the most favorable feedback of the three alternatives that were presented. This alignment includes a lane reduction or “road diet,” on-street parking, bulb-outs, pedestrian refuges, landscaped medians, and center turn lanes (Figure 1). This configuration is the most pedestrian-friendly and would create a street wholly unique within Albuquerque: a narrow, safe, walkable commercial corridor where pedestrians would only have to cross one lane of traffic at a time. Due to the narrow right-of-way, this alignment does not allow enough room for bikes. Instead, bicycle traffic would be diverted through nearby residential streets that are already in use as formal and informal bike routes. Over time, the alleys behind businesses could even be turned into bike routes or bike boulevards.
Figure 2: Cross-Sections of Alternative 2. The top figure indicates the normal alignment, and the bottom figure shows the alignment at pedestrian crossings.
Figure 3: Cross-sections of Alternative 3. The top figure indicates the normal alignment, and the bottom figure shows the alignment at pedestrian crossings.
Figure 4: Cross-Sections of Alternative 4. The top figure indicates the normal alignment, and the bottom figure shows the alignment at pedestrian crossings.
Alternative 2 includes a lane reduction from four lanes to two lanes, on-street parking, bulbouts, and bike lanes (Figure 2). In this scenario, the medians, turn lanes, and pedestrian refuges were removed to make room for a bicycle route connecting the corridor to the north and the south. The pedestrian crossing would be an improvement over existing conditions, since the bulb-outs would reduce the crossing distance from 48 feet to 32 feet. However, there would be no pedestrian refuge in the middle of the street, making the crossing more difficult for vulnerable individuals. Of particular concern, the traffic flow would likely deteriorate in Alternative 2, since the road would be reduced to one lane in each direction with no turn lanes. As a result, vehicles waiting to turn left could create significant delays and congestion despite the relatively low traffic volumes. Without a median, landscaping opportunities would be limited to the bulb-outs and private properties. Alternative 2 received the least interest at the July 2 meeting, and it was not analyzed in depth after that point.
Alternative 3 consists of a lane reduction from four lanes to two lanes, bike lanes, medians, left turn lanes, and pedestrian refuges. In this alignment, which also received interest at the July 2 presentation, the on-street parking and bulb-outs were removed to make room for the bike lanes. This is the most bicycle-friendly configuration, but it is less pedestrian-friendly than Recommended Alternative 1 due to the lack of bulb-outs. The pedestrian crossing would be reduced from 48 feet to two 19-foot crossings, which is very manageable for most groups. The bike lane would also create a larger space between pedestrians and passing vehicles, increasing pedestrian comfort and safety. However, Alternative 3 does not include on-street parking, which could otherwise be very beneficial to local businesses. Rather than encouraging people to park and stay in the area, San Pedro would continue to be used primarily as a through corridor. While installing bike lanes instead of on-street parking might be advised in a residential part of the street, it is not recommended in this business corridor.
Alternative 4 was created after the July 2 meeting to respond to local business concerns that a lane reduction would result in decreased traffic and a declining customer base. In Alternative 4, San Pedro retains its existing four-lane alignment, and the lane widths are slightly reduced. Because the right-of-way is so narrow, this leaves little room for any additions, and accordingly it was not presented as one of the original alternatives. By reducing the lane width, the corridor would gain a total of four feet to use for landscaping purposes, since four feet is not enough for dedicated bike lanes, turn lanes, or on-street parking. In Alternative 4, the lane widths are reduced from 12 feet to 11 feet, and the speed limit could remain at 35 miles per hour or be reduced to 30 miles per hour. Even without reducing the speed limit, shrinking the size of the lanes, consistent with the AASHTO Green Book and Designing Walkable Urban Thoroughfares, would help slow traffic.
Figure 5. General roundabout design. Source: Federal Highway Administration. Despite these benefits, one key challenge to implementing a roundabout at Constitution is the intersection’s role as a major crossing point for Mark Twain Elementary School. There are no formal pedestrian crossing signals at roundabouts to guide schoolchildren across. The implications for school crossings are unclear, and a roundabout would undoubtedly make the job of a crossing guard more challenging. For these reasons, most community members opposed a roundabout at Constitution, instead preferring the straightened option presented in Recommended Alternative 1.