The effects of on-site parking management programs, transportation demand management (tdm) promotional efforts, and off-site environmental factors on the success of tdm programs at six large medical institutions in san francisco, california, are investigated. The monthly charge for employee parking on site was found to be the single most influential factor for determining the percent of employees thatdrive alone to work. This single factor accounted for up to 80% of the variation in mode splits among the six institutions. The monthlyparking charge at each medical institution was found to be highly correlated to the severity of off-site parking restrictions and the abundance of off-site transit service. These latter two factors were the next most influential factors (after on-site parking pricing) ontdm program results. These latter two factors together explain 50% of the variation in tdm program success among the surveyed institutions. On-site parking supply was a much less significant factor because of the availability of off-site parking in the residential neighborhoods surrounding most of the institutions. Because of the generalsimilarity of the six institutions surveyed, the relative size and characteristics of the medical institutions were found to be the least important of the factors studied for influencing mode split success. An increase of $8.00 A month in employee monthly parking chargeswas found to be necessary to decrease employee drive alone mode splits by one percentage point. (The 95% confidence interval for this result is between $5.00 And $33.00.) The monthly parking charge is highly correlated to off-site parking and transit conditions. Consequently, to achieve the mode split improvements implied by the results of this analysis it is necessary to parallel the on-site parking charge increases with increased restrictions on off-site on-street parking and improved transit service. This paper appears in transportation research record no. 1321, Rideshare programs: evaluation of effectiveness, trip reduction programs, demand management, and commuter attitudes 1991.
Abstract