Agenda 11-07-19 Item 6-a - NC 54 West Corridor Study - Phase 2

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12 MPO Board 10/9/2019 Item 8 Ref: 38587.01 October 1, 2019 Page 6 • Growth in the east is concentrated in Chapel Hill, primarily in nodes along NC 86 and US 15/501. Particularly relevant to this study is the Lloyd Farm development in the northeast quadrant of the NC 54/Old Fayetteville Road intersection. TRM Comparison to StreetLight Insight Analysis A select-link analysis was performed using the Triangle Regional model (TRM v6)to provide a comparison against the StreetLight analysis described previously for the eastward distribution of trips to/from a point on NC 54 just east of Orange Grove Road. Because of minor anomalies in the Base Year network loading at the western end of the corridor, some manual adjustments were necessary, and comparative runs for 2045 Build and No-Build scenarios were also conducted. The results are summarized in Figure 12. The major differences between the TRM the StreetLight trip distributions occur at the eastern end of the corridor.Just east of Old Fayetteville Road, both analyses estimate between 82%and 83%of eastbound trips from just east of Orange Grove Road are still on NC 54. But the TRM distributes 5%fewer trips north on Old Fayetteville Road, and loses none at Carrboro Plaza.This leaves 77%of the original trips, as opposed to 66%according to StreetLight. More importantly,TRM assigns a far higher proportion of these trips to West Main Street. TRM has 25%of the initial traffic turning on West Main Street(versus 12%according to StreetLight), and 52%continuing down NC 54 Bypass (versus 54%). This works out to a 68%/32% (or 2.1 to 1) split between n NC 54 Bypass and West Main Street. The Streetlight analysis yielded a split of 82%/18% (or 4.5 to 1). This difference is probably attributable to the fact that regional travel demand models like TRM tend to under- estimate intersection delay as congestion increases, especially through denser downtown areas. It also appears that trips to Carrboro Plaza and up Old Fayetteville Road (including McDougal Middle School) are either under- represented or inaccurately routed. TRM Comparison of Build (Widen NC 54) and No-Build Scenarios To estimate the traffic impacts of the proposed widening of NC 54 on traffic patterns,two 2045 TRM networks were compared. Both have identical socio-economic data and include all transportation improvement projects assumed in the latest DCHC Metropolitan Transportation Plan (MTP). The only difference is that the Widen NC 54 (Build) Scenario, a 45-mph 4-lane divided cross-section is assumed for NC 54 between 1-40 in Graham and Old Fayetteville Road in Carrboro. The No-Build Scenario assumes the existing cross-section is maintained. After trips were distributed and assigned to the two networks, daily volumes in the No-Build network were subtracted from the corresponding link volumes in the Build (widen NC 54) network. Results are summarized in Figure 13. Where traffic volumes are higher in the Build scenario (due to diversion from other routes), links are shaded red and given bandwidths corresponding to the magnitude of the increase. Where traffic volumes are lower in the Build scenario, links are shaded blue and assigned bandwidths corresponding to the magnitude of the decrease. Changes in daily traffic volumes are indicated on representative links. Changes of less than 100 vehicles/day are not represented.Volumes for West Main Street and NC 54 Bypass were adjusted to compensate for Page 6 of 12